The Levers

My first concern was the plastic levers that are pushed to rotate the base and planes of tilt and shift. By the way – the forward lever isn’t broken – its base is built at an angle to keep it away from the shift rotation knob. Well done, Samyang engineer.

I removed the screws and plates over the levers, of course but I can’t get a decent photo inside. It’s dark in there. The plastic tabs slip over a metal tab that does the actual work inside. It’s effective and tight right now when the lenses are new. I honestly expect this will be a problem area as the lens gets used.

It would be no big deal if you could buy the plastic part; anyone could change it in about 30 seconds. But RokiBowYang parts aren’t available. If anyone from Rokinon reads this, here’s the one thing you could do to increase the popularity of this lens long-term. Sell the plastic parts. You don’t have to open up a parts department: just put all the plastic knobs and levers in a plastic baggie, call it a ‘refurb kit’ and sell it at B&H.

Opening up the Base

We’ll start by removing the 4 screws that hold the shift mechanism to the tilt mechanism. I should mention that the lens is made out of very high grade plastic that is quite thick and solid.  I have no reservations about these parts. It’s similar to the material the new Canon 24-70 f/2.8 II lens is made of.

The shift plate comes right off. . . .

. . . from the tilt mechanism and optics. A couple of points in this area. The gears themselves are solid brass as you can see above, but the tracks they run in are plastic.

The same goes for the shift assembly in the lower section.

Most other tilt-shifts have brass tracks and gears. That being said, it’s not necessarily a bad thing. The Canon 70-200 f/2.8 IS lenses (including the IS II) have brass gears running on nylon tracks for the zoom ring. But, we do have to replace those every so often because a nylon tooth gets torn off. I will say these are nice, thick plastic teeth, though, so hopefully they’ll hold up well.

Also note the focus key (forked aluminum piece at 3 o’clock in the picture of the optics and shift mechanism, above). We had 3 of 8 lenses that made a scraping sound and sensation when focusing and it’s from the key, which is a piece of stamped aluminum with rather rough edges (see below). Not a big deal, I mention it mostly to let you know not to worry if yours scrapes a bit when focusing. It probably will go away as the rough edges wear off with use.

Back to work. A few more screws and the tilt mechanism comes off.

After which the aperture ring slides off. You can now see the rear optical assembly. It’s a single piece basically, with the elements held in place with glue and retaining rings. It moves as a group when focusing.

Opening Up the Front

Moving around to the front of the lens the makeup ring removes by unscrewing.

Three more screws remove the filter ring.

Showing the 4 screws that hold the retaining ring over the front group.

With these removed the front group comes out as a unit.

Like the rear group, the front group does not have any adjustable elements, simply shims between elements. This group is fixed, not moving along a helicoid track.

A spanner wrench would allow us to open the group and replace the front element, but since there are no adjustable elements inside we didn’t open it up further.

Inside the empty front barrel we can now see the 3 screws that hold the rear group in place. Again, since it’s a sealed group with no adjustments, we didn’t see any need to mess with it.

From the side you can barely see the single helicoid that focuses using the entire rear group.

Conclusions

The original purpose of this disassembly was to try to get an idea about reliability of this lens. I’m left with only the single concern I had when I first examined the lens; I’m afraid the rotation-locking levers might break. That would be absolutely no big deal if the parts were available to repair it. Anyone could do it at home in 30 seconds. Without parts, though, a broken lever means you won’t be able to rotate the planes of tilt and shift.

I have very mild concern about the plastic gear rails for the tilt and shift mechanism, but it seems sturdy plastic and I’m pretty hopeful they’ll hold up well.

Otherwise the lens is really quite well made. Yes, there’s lots of plastic, but it’s very high-quality, heavy plastic with long, thickly-threaded screws holding things together. I have no concerns about the lens from a materials standpoint.

I came away with a lot of admiration for the Samyang engineers who designed this thing, and perhaps some understanding about why the lens is what it is. The design is simple, modular, and logical. That is, I expect, why the lens can be produced with high-grade materials for such an aggressive price. The disassembly took about 15 minutes, tops. Obviously assembly at the factory is going to be quick and staightforward, too.

That being said, the modular design of the two lens groups (front and rear) are a huge cost savings. There are no tilting or centering elements to adjust during the assembly process.

<begin speculation> That may (and I’m completely speculating now) also be why the resolution isn’t quite what the Canon or Nikon lenses have wide open. When designing a lens, the designer has to take into account how much variation to allow. With certain designs a given element might have to be within 0.01mm of a proper spacing distance or 0.01 degrees of tilt off the axis (I’m pulling numbers out of the air for an example) or the lens will be decentered. A more forgiving design might allow 4 or 5 times the margin of error, but in exchange allows more aberration or has a lower resolution.

It seems logical that such a compromise had to be made in the Samyang lens to allow such efficiency of assembly. The designer probably took into account that many people shoot with this type of lens stopped down, where the aberrations are minimized and the resolution very good, and decided that compromise was worthwhile to allow the lens price to be kept so reasonable. </end speculation>

Aaron Closz and Roger Cicala

All images copyright Roger Cicala, 2013 and may not be reproduced without permission.

All hands in images courtesy of Aaron Closz.

Lensrentals.com

May, 2013

Unlike most photography gear, ballheads are elegantly simple. They have only a few parts. There’s the ball itself, of course, and the external case. Between the ball and the top of the case is a form fitting bearing. The bearing material (not visible in photo) is a firm plastic that has low friction, but it distorts a bit with pressure, exerting more friction at higher pressures. Many balls, like this one, have an opening in the bottom.

You can see the three knobs of this ballhead. The one on the lower right is the friction knob for the panning (or rotating) baseplate. The left knob and top knob are the lock and drag controls, which pretty much do the same thing (which is why some ballheads only have one friction/locking knob).

You may barely notice that the upper knob is attached to a push rod with a 30-degree angle, while the left knob has a flat push rod. (In this picture the ball has dropped back towards the push rods. Assembled it’s about 5mm further forward, away from the base.)

A plastic bearing cup fits beneath the ball. Like the upper bearing, it’s nearly frictionless with no pressure is applied, but grips quite tightly when pressure is applied. Unlike pan-tilt heads, ballheads don’t need internal lubricants.

The next piece is a conical plastic compression ring that fits over the bearing and provides the magic tightening of the ballhead. Notice there’s a partial-thickness groove cut in the cone, which fits over the ridge in the bearing cup, holding things in proper alignment.

On the opposite side there is a gap in the ring. When you turn the friction or locking knob, this opening is compressed. Since the ring is cone shaped, compressing the opening forces the bearing plate more tightly against the ball, increasing friction and resistance. Like I said, simple and elegant.

Of course, the ballhead needs a very sturdy base under the conical plate, so that the pressure from the adjustment knobs all goes up to the friction plate and ball. In this case there’s a 1mm thick steel plate with a 1mm thick steel washer beneath that, held in place with an equally thick e-clip. The remaining space is taken up by the rotating (panning) base plate, which is attached by 4 screws (you can see the screw holes in the bottom of the case).

Takeaway Message

Ballheads are pretty simple things. Taking one apart shows why, when properly taken care of, they seem to last for ever.

The difference between the best ones and the less-than-best ones isn’t (as far as I’ve been able to tell) any secret new technology. Rather it would be in the materials used for construction. The best heads have aspherical balls and use higher cost materials for the friction plates, conical plates, screws, and housing.

For moderate weight (say a camera and 70-200 f/2.8 lens) used occasionally (a couple of weekends a month) the difference isn’t huge, especially with a new-out-of-the-box ballhead. With heavier weights and heavier usage, more durable bearings and particularly screw stems should improve reliability and lifespan. When we see a ballhead die, 90% of the time it’s because a friction knob’s threads are stripped or the rod bent.

Roger Cicala

Lensrentals.com

April, 2013

We’ve been doing a lot of teardowns lately and I’ve made comments like “well thought out” or “carefully engineered.” Several people have asked me to show them some comparisons so they can see what I’m talking about. Given that we have fairly modern releases of 24-70mm f/2.8 lenses from several manufacturers, we thought it would make sense to compare what the insides look like.

We’ll compare the Canon 24-70 f/2.8 Mk II, the Nikon 24-70 f/2.8 AF-S, and the Tamron 24-70 f/2.8 Di VC.

This will largely examine the electro-mechanical mechanisms in the lenses. But just for completeness here are the optical diagrams for all 3. The Canon is the most optically complex, containing 18 elements in 13 groups. The Tamron has 17 elements in 12 groups, while the Nikon has 15 elements in 11 groups.

The Front Group

One thing that all 3 of these lenses have in common is a large front group at the end of an extending barrel. They all disassemble the same way – a makeup ring is removed exposing the screws that let us remove the front group from the lens. The Canon front group is pictured below but they’re all very similar — 2 or 3 glass elements permanently set in a plastic case.

I will include an image of the Tamron front group below to show the variable thickness shims used to obtain proper spacing (two on the element, one lying beside it). Both the Tamron and Nikon lenses use shims to space the front element. The Canon does not.

I also want to show one close-up of the Tamron front group because the back element of the first group (element #2) was the one we had reported coming loose in a couple of early copies. This copy (which is more recent) shows a very hard plastic seal rather than the softer glue we had seen in those early ones. We may have gotten a couple with defective seals in those early copies, or Tamron may have changed things. Either way, we haven’t seen that problem in a long time now.

Opening up the Back

Since we’re doing this to show internal differences, I should start with some generalizations. The Canon 24-70 f/2.8 II is typical of most newer (last 5-6 years) Canon designs. The Nikon 24-70 is quite typical of a Nikon lens, which haven’t changed very much in the last decade. Sony lenses tend to be very much like Nikon lenses. Sigma and Tamron lenses used to be much like Nikons, too, but recently are morphing and taking on some of the characteristics of Canon lenses.

Nikon Preliminaries

For all 3 lenses, opening up the back involves removing the screws that hold the bayonet mount and electrical connections in place. For the Nikon there is an additional step: the rear element of this lens is attached directly to the inside of the bayonet mount and is removed first. This is a bit unusual but it is convenient if you need to clean the inside of the rear element.

The Nikon lens also has electronic position-sensing brushes under the zoom and focus rings that have to removed before any disassembly takes place.

The focus brush is smaller and deeper, so it’s difficult to show you until it’s removed.

Under the Bayonet Mount

OK, once we’ve got the Nikon de-accessorized, the rear bayonet mount of all three lenses is removed the same way. (You’re also beginning to see why it takes a little more time to work on a Nikon lens.)

Nikon

The bayonet mount contains the long lever that actuates the mechanical aperture mechanism.

There’s a spring in the mount that returns the aperture lever to neutral position if the camera isn’t actively moving it. Some Nikon lenses have two springs, some just one.

Underneath the bayonet mount are more shims. For most lenses shim thickness at the bayonet mount adjusts proper infinity focus. If you change a bayonet mount, you’ll generally need to alter the shim thickness, etc.

 Canon

There’s not much to show with the Canon bayonet mount. There are no shims. Canon bayonet mounts come in various thicknesses, so rather than shimming they simply choose the correct thickness mount when they assemble the lens.

There are no aperture control levers and springs because the aperture is controlled electronically. Springs and levers bend and break, but electronics burn out. If there’s any reliability difference between electronic and mechanical aperture control I’ve never noticed it.

With the bayonet mount and rear barrel mount removed from the Canon lens we’re looking straight at the PCB (printed circuit board) where all the electrical connections live – typical for Canon lenses. If you scroll back up, you’ll notice the Nikon lens doesn’t have a PCB.

Tamron

We dissected a Canon-mount Tamron, so it doesn’t have a mechanical aperture lever. Had we done a Nikon-mount version then the bayonet mount would have had an aperture control lever, like the Nikon. Like Nikon, however, the Tamron (and most third-party lenses) use shims under the bayonet mount to achieve proper spacing.

Under the shim, however, the Tamron has a PCB like the Canon. Older third-party lenses generally didn’t have PCBs, but in recent years most are using them. I particularly like Tamron’s because they are a very cool black color. I assume the plug with green marks on it is a computer connection for factory adjustments.

The black PCB also makes for lovely bokeh from the electronic components if we take a through-the-lens shot of my workbench.

Removing the Rear Zoom Components

Canon

With this one I’ll start with the Canon lens, since it’s the most straightforward.  After the PCB is off we remove several screws . . .

. . . and the entire rear barrel assembly comes off as a unit. This contains zoom mechanism and keys, the zoom brush assembly, and the lens switches.

The optical elements and ultrasonic motor  (silver thingie with slots near the top) remain behind.

Removing one more set of screws removes the ultrasonic autofocus motor section from the optical portion of the lens. Simple, sweet, and logical.  It’s a dream to disassemble. Most recent Canon lenses have this type of modular assembly.

The Nikon 24-70 f/2.8 AF-S comes apart a bit differently. The zoom key is removed first.

Then the zoom ring is removed simply by lining everything up properly and lifting.

Then we can remove the screws holding the mid barrel in place and slide it off.

With the mid barrel removed we now see why the Nikon lens doesn’t have a PCB at the back. Nikon uses several small circuit boards connected by flex cables and even some soldered wires, wrapping them around the inner barrel. It doesn’t look quite as elegant but it works just fine. This is how lenses have been made for years.

On the other side of the lens we can also see the GMR (Giant MagnetoResistor) unit — the slivery piece held on by two screws at the left of the image below. The GMR is the position sensor Nikon and many third-party lenses use. In the spirit of ‘don’t do what I did, do what I say’, I’ll tell you don’t ever touch that with a finger. If you do the lens no longer works and the unit has to be replaced by Nikon and Aaron will give you that look he gives when you’ve done something really stupid.

Newer Canon lenses use a smaller optical sensing unit tucked inside the barrel of the focusing unit we removed above. Even though this is the Nikon section, I’ll show it below for comparison. The limited research I’ve done found that both types of units are available in a wide variety of accuracies, so I don’t know that one type is better than another. The optical units are a lot smaller and out of the way if you open up a lens, but I doubt many of you care about that.

The Nikon ultrasonic motor is the next disassembly step. Unlike the Canon lens it doesn’t come off as a unit — it has to be disassembled piece by piece. Underneath it there is a soldered wiring harness so complete disassembly involves desoldering some wiring, too. That’s a time consuming process that we’re not going to go through for a demo.

Tamron

Once it’s PCB is removed, the Tamron shows some traits similar to both the Nikon and the Canon lenses. It doesn’t come apart modularly like a Canon, but it is a bit more organized inside than the Nikon. The aperture key (screwdriver is removing it’s screw) need to be removed, along with 4 mounting screws, then the mid barrel comes off.

The mid-barrel contains the Tamron’s GMR unit.

With the mid barrel removed we can see the Tamrons ultrasonic motor, which is very similar to the Nikon and Canon motors.

The Tamron isn’t quite as modular as the Canon, but the USM assembly does come off easily as a unit.

Optical Element Adjustments

While we’re not getting into the optical elements too much in this teardown, I will take a minute here to demonstrate one of the main differences between the lenses. Notice the rear part of the Tamron optical assembly two images above (the picture with the forceps) and you’ll see several screws holding the rearmost group onto the optical assembly. If we take those screws out we remove the rear group.

As shown in the image below, under each screw is a set of shims – different thicknesses of the three shims could both space and correct tilt of the rear element. Notice also there are three more screws holding the next element in place (each of these screws is just to the left of the rear element screw posts with the brass shims still in place).

Removing these screws lets us remove the next element, which shows a set of spacing shims. Changing shims here would adjust the spacing between elements, but not the element’s tilt.

Most lenses (including most Nikon and Sigma) use shimming to adjust most of the optical elements. Canon lenses tend, instead, to have helical collars on the lens elements. Rotating the collars tilts the element forward or backwards.

Conclusion

Well, if you’ve gotten this far, you have earned the Geek Scout Merit Badge for lens teardown. You may (or may not) have also gained some appreciation for why it costs so much to do a ‘simple’ repair on some lenses.

There are certainly differences in how the various manufacturers design the non-optical portions of their lenses. Third-party lenses used to be very similar to Nikons but recently are starting to, uhm, borrow some of the designs Canon has used.

From an photographer’s standpoint, one design isn’t better or worse. They all make lenses that work just fine.

But a number of you have asked us to demonstrate why we call some designs ‘cleaner’ or more organized than others. Hopefully this demonstrated that, at least to some extent.

Roger Cicala and Aaron Closz

Lensrentals.com

January, 2013

Of course we had to do it. One of them was soft, you see, and we were really curious about how that Macro mode switch worked and  . . . . OK, we just wanted to. Actually, we’ve found the new 24-70 f/4 IS is a most interesting lens inside.

So as usual, Aaron is doing the disassembly while I’m doing the photography and writing.

Up Front First

There’s a plastic cosmetic ring that pops out.

Which uncovers the 6 screws holding the front group in place. Like the 24-70 f/2.8 Mk II (and unlike the Mk I) there are no adjusting tilt or centering screws on the front element.

With those out the front group is comes right out. Hopefully this will keep replacement costs for a scratched front element low.

Underneath the front element, the distal barrel / filter ring is held on by an arrangement we’ve never encountered before.  Each of the 6 screws mounts through a metal sleeve, compressing a spring as it tightens the front barrel in place.

As is often the case when we see something new, we aren’t certain what the purpose is. Our first thought was shock absorbing, but the screws are tightened down pretty well so there’s no spring action. Our second thought was front element tilt (by tilting the whole barrel) but we see no shims or washers that would (we think) be used if that were the purpose. On the other hand, one of the lenses we received that was soft at 70mm had a couple of these screws a half turn loose and was much better after they were tightened.

Anyway, if you take these screws out, the distal barrel / filter ring comes right off. (Since we did not know their purpose, we considered not messing with them. For about 2 seconds.)

Again, this should make a simple repair when a filter ring breaks. Just for demonstration purposes, a couple of shots with the internal barrel zoomed out to 70mm and back to 24mm (retracted).

We left the tube/spring assemblies in place with the screws removed to show them again. Maybe one of you can explain what they are. (That’s a subtle hint to any Canon techs who are visiting. We haven’t outed anyone else who told us stuff we aren’t supposed to know. We won’t out you either — we’ll just say we figured it out ourselves, OK?)

BTW – this second element is one of the focusing elements. Notice the focus key at 11 o’clock in the picture above. OK, that’s all there is to see from the front of the lens, so have a cup of coffee while we put this part back together and move to the back side.

 The Back Side is More Interesting

The back comes off in the usual way, showing us the main PCB. Other than a rather amazing 8 flexes that have to be unplugged it’s pretty routine.

The PCB has a bit more circuitry than older lenses, laid out in Canon’s usual efficient and orderly fashion. There are a number of flush-mounted components, many covered by heavy electrical shielding tape.

At this point we come to another thing we’ve never really seen before, at least not to this degree. The single rear element is sort of on stilts, projecting out to the back of the lens all by it’s lonesome – at least with the lens racked out to 24mm (more on that later). That’s a big gap between the rear element and the next element forward.

There are a healthy number of screws (8 if I recall correctly) holding the rear barrel in place. Once it’s removed we again see Canon’s usual tightly organized flex runs to the switches in the barrel. I know it doesn’t make a bit of difference in what kind of pictures it takes, but it makes me feel comfortable knowing some engineer has taken the time to map out each flex run, etc. Wish some other manufacturers did.

One thing I was very interested to see was the zoom lock-macro switch and how it worked since this is a first. The good news is the switch is easily removed or changed from outside with no lens disassembly — it’s a simple mechanical switch with a plastic tab that slips under the zoom ring fully to lock, and must be pulled back against a spring to allow Macro work.

I mention it’s good that it’s accessible because I’m going to be replacing a lot of these. It probably won’t affect any of you who buy the lens, but I guarantee renters who aren’t familiar with the macro switch are going to force it (which I tested and it’s easy to do) and eventually break this little plastic tab off. That won’t have any bad effects other than letting you accidently move into macro mode, which I doubt will be a problem for anyone, really.

A few more screws and the motor – focusing assembly unit comes off. I really like how Canon is putting this as a removable unit in their newer lenses. It makes disassembly and repair much simpler. Maybe that’s one of the reasons Canon repair prices are more reasonable.

With the motor unit off the internal optical assembly containing all lens elements, helicoids, etc. is left as a group.

This gives us an opportunity for a clearer look at that rear element. At 24mm focal length it sits up there looking rather lonely and vulnerable.

As you zoom the lens out, though, it moves forward at a brisk pace. At 70mm it’s tucked inside the barrel, right up against the next optical group.

The most interesting thing is when the switch is flipped and the lens moves into macro mode, the rear element and next group move even further forward, moving as a single group.

From the outside of the optical group, you can see the very long helicoid groove that causes this large amount of travel. For those who don’t look at helicoid grooves often, they are usually simple, smooth curves. If you’re a weird photo geek, you can trace them out on paper and reproduce exactly how the elements move in relation to each other (I don’t know anyone who would bother to do weird stuff like that, of course).

This groove is unique. I’ve never seen one like it. You can see the notch in the groove (red arrow) that begins macro mode, with a different curve above and below that notch. It shouldn’t be surprising, I guess, since in macro mode infinity focus is given up and the elements are used to bring much nearer focus than would otherwise be possible. But I’ve never seen anything quite like it. Brilliant idea and the engineering and design mathematics involved must be most formidable. I haven’t found it, but I’m certain there’s a patent out there somewhere for this. It really is like having two different lenses in one.

Finally, one of the things we tend to look at is where the lens is optically adjusted. It probably shouldn’t be surprising that such a complex lens has a complex adjustment setup. As is usual for Canon (and one of the things all PhotoGeeks love) most of the adjustments are done through oblate collars, allowing very fine tilt and centering movements, unlike the shims used in many other brands.

Two of the rear groups have white nylon adjustment collars. I’m pleased to note they are thick, heavy-duty collars so they should be less likely to break or wear with use. The upper (leftmost in the picture) collar is very obviously oblate so it will allow large movements, while the lower (rightmost) is a more subtle adjustment.

Deeper in the optical barrels are two forward elements that are adjusted by brass-collared screws. I’ve marked them with red arrows since they’re more difficult to see.

That’s at least 4 adjustable groups in this lens, which is more than most lenses have. Again, it makes sense – this is really two lenses in one. I’m guessing some of the adjustments will be largely effective at only macro ranges, while others will have more effect at normal shooting ranges.

 Conclusion:

Well, this was one of our longer teardown posts and I assume we’ve lost everyone but the true geeks by now. But the Canon 24-70 f/4 IS is a truly interesting design, with some things that we’ve never seen before.

Some worry me a tiny bit. I’m certain the zoom-lock/macro switch is going to break some, although it doesn’t appear that will have any major effect.

The large number of adjustable elements is a bit concerning, too. In theory, at least, that’s more adjustments that could contribute to sample variation. On the other hand, Canon’s been a long time developing this lens and they engineer lenses more logically than anyone else. I suspect there’s a nice thick document I’ll never see that tells techs exactly which of those adjustments controls which aspects of the lens’ optics.

In some other lenses, where one element is used to adjust several variables the adjustments can be ridiculously finicky to make. It might well be that having more adjustable spots will make the adjustments more straightforward and logical, reducing sample variation. Only time will tell on that one.

Roger Cicala and Aaron Closz

Lensrentals.com

January, 2013

Left to right: 5D III, 6D, 5D II

So, yeah, the 6d is smaller and all. But that wasn’t quite what we wanted to see. So, as is our habit, a few screws here and a few screws there and . . . .

Disassmebling

One thing was noted right away. Where the other Canon cameras tend to come apart in modules (you can take off the back, or take off the front, etc.) the 6D was a bit more interconnected. To get the back off required removing the sides and a bit of the bottom for example. A bit of a pain for the exploring types, but I would imagine it also gives more structural support.

The body is basically plastic, but like most modern plastics it’s thick and solid. Never a thought that a screw was going to strip out during disassembly. Anyway, after a bit the back was off, and looks, from the inside, pretty similar to all the other Canon backs.

Inside of back assembly

Back to the back of the camera, things are nicely laid out. Flexes have short, neat runs. The shield tape in the lower right isn’t just laid on top, it runs around to the bottom and sides of the assembly for 1/2 inch or so. Under the tape is both an aluminum shield and then a soft rubberized shield. It seems a lot of attention is payed to electrical isolation.

For the electroGeeky among us (you know who you are) a chip close up so you can tell us what the various chips are. I’m way too far behind today to look them all up.

And removing the shielding on the right side shows us that hefty Digic 5+ chip and a companion.

The SD card slot is affixed to the underside of the PCB, along with a few other chips.

That appears to be the date-time battery over on the right, so you won’t be taking it out to do one of those ‘hard resets’ so often spoken of, yet so rarely successful.

Underneath the PCB, you can see how clean and nicely laid out all of this is.  No long wire or flexes running hither and yon, every connection exactly where it needs to be when the board is reseated, and more metal shielding almost entirely separating the circuitry back here from the magnets and motors up front.

And, of course, none of this makes a bit of difference when you go out and take pictures. But I always like seeing nice clean engineering, and this is another example of it.

RogerCicala

Lensrentals.com

November, 2012

The optical formulas are quite different, for example.

Optical diagram of the 20mm (left) and 14mm (right) pancake lenses

While the performance of both is excellent, like most pancake lenses there is a bit of softness in the corners wide open.

MTF charts for the same two lenses

They also differ in focusing method: the 14mm is internally focusing; that is one internal group moves when the lens is focused. The 20mm focuses by moving the entire lens assembly, making the lens physically longer at closer focusing distances.

Both, however, are ‘focus-by-wire’, meaning that when you turn the focus knob you aren’t actually focusing the lens; you are sending a signal to the electronic motor that actually moves the focus element. Probably because only one group is moving, rather than the entire lens, the 14mm has the reputation of focusing more rapidly and being quieter during focus.

There is one other difference that has gotten some attention lately. The 20mm lens is known to cause banding when used on the Olympus OM-D camera. I entered a discussion about this on DPReview, and ended up volunteering to open the lenses and see if we could find anything that might contribute to the banding.

If you don’t like reading geeky stuff and looking at undressed lenses, the answer is we didn’t, so you can move along now. For my fellow geeks, though, let’s have a look inside.

Open Them Up Already

Looking from the mount side, the lenses show a lot of similarities. Same 3-screw light baffle, same 3-screw mount, and the same electronic connector (DUH).

20mm (left) and 14mm (right)

Removing the light baffle led to our first surprise, and we’ve now renamed the 20mm lens The Jack-In-The Box.

The spring has something to do with the fact that the lens assembly extends for close focusing. Whether it helps the motor move the lens, or the motor only moves the lens back and the spring moves it forward, I can’t say. But if you put the lens back together without the spring, it doesn’t focus. (Pretty simple way to figure it out, huh?)

OK, back to work. Removing the mount is straightforward and shows the rear barrel assemblies are about identical except for size.

Three screws take the rear barrels off, fully exposing the PCBs (main circuit board). You can see the focusing motors for both lenses in similar locations, although quite different in size, as you would expect. (Remember, the 20mm has to move the entire lens, not that it’s a huge thing to move.)

One significant difference does show now. Notice on the 20mm (left) the toothed pattern along the manual focus ring. The 14mm has a similar arrangement, but it’s a layer deeper. As we’ll see later, the teeth pass through an optical sensor that then sends focusing signals to the AF motor when you turn it.

Here’s a close-up of the sensor and teeth in place. The flex cable connects the sensor to the main PCB.

Removing the PCB cleans things up a bit but doesn’t really show anything new.

Internal view of 20mm (left) and 14mm (right)

The 20mm, on the left, shows the large focusing motor in the upper right section and the top of the smaller aperture motor at about 4 o’clock from the lens elements. With the 14mm we can also see the focusing motor at the top of the image, and 3 screws that are next in line for removal.

Removing the 3 screws from the 14mm lets us remove all of the optics and motors in one piece; they drop right out of the housing. If we flip it over we’re looking at the front element. Now we can see the focusing motor at the top, and the brass gear of the aperture motor. The screws tell us there’s some further disassembly we could do, but that would almost certainly involve taking out the aperture blades and other things that are really time consuming.

The 14mm internals

At this point, though, I notice the motor bodies and their electromagnets are towards the front of the lens. I really doubt the motors have anything to do with the banding reported with the 20mm. If they did, though, the smaller motors put toward the front of the lens might be helpful in preventing that with the 14mm.

As an aside, now that the main lens assembly is removed we can see an identical optical sensor and toothed focus ring, like the one on the 14mm. It’s simply set forward and inside the lens case, so it’s less apparent from the back.

Optical sensor from behind.

20mm Internals

The 20mm has another ‘something different’ for us: the focusing ring is held on by a large retaining ring that easily unclips, letting us slip the external focus ring off.

20mm with retaining clip removed

Which then lets us remove the focusing motor. It’s rather unremarkable.

 The main part of the lens still sits in the lens housing.

Notice the small, square posts with holes in the center that are set in the focusing ring; you can see 4 of them in the image above. We can lift the central part of the lens out of the housing now, which shows us the grooves in the focusing ring. Pancake lenses don’t have helicoids; the lens slides forward and backward during focusing because when the ring rotates, curved grooves inside move the lens backward and forward.

As with the 14mm, we chose not to disassemble the internal elements. There are no apparent optical adjustments that can be made and disassembling the diaphragm is time consuming.

Conclusion

I don’t think our little dissection shows anything that is directly attributable to causing banding, because I would expect it is some electronic component on the main circuit board, which is well beyond our capabilities to analyze. The 20mm does have a larger AF motor that is less well shielded, but I doubt this has anything to do with the problem – the motor isn’t running when people are taking photographs.

Roger Cicala

Lensrentals.com

October 2012

But then we realized Kristin and Tyler had a baby yesterday (congratulations!!!!) so they aren’t here. Drew is running the place by himself and far too busy to check and see if the guys in the repair department are taking something apart they shouldn’t. So as long as the lens got put back together and shipped out on time, who would know?

Seriously, though, I really, really wanted a look inside this one. I’ve written for years about how much copy-to-copy variation there is in the original 24-70 f/2.8 and how it requires optical adjustment almost any time it’s dropped or misused in the slightest.

A group of 24-70s on their way to Canon for optical adjustment

So I wanted to look inside and see if things might be different with the new lens.

The Front Group of the 24-70 Version I

I put this part separately because I’m convinced the front element design of the original 24-70 f/2.8 accounted for a lot of its problems. The front element is a big, heavy piece of glass, but in the original version it is also the element that is adjusted for centering via screws around the edges.

Version I front centering adjustment

It also adjusts for spacing from the other elements via a sliding ramp.

Adjustments for front element spacing

Finally, it has a set of eccentric collars that adjust the tilt of the element.

Collars to adjust front element tilt in the original 24-70

Given all of that adjustability involving the front element, I’ve never found it surprising that the original 24-70 was bad to drop. It often appeared fine after being dropped, but had actually become decentered and image quality suffered. The bottom line of all this is that I hoped the new lens had a different design for the front group. Guess what?

The New Lens has a Different Design for the Front Group

It has a new design for almost everything else, too. But let’s start at the front. As usual, Aaron is doing disassembly honors while I take pictures and make helpful suggestions like, “Don’t tear that flex.”

After peeling off the makeup ring, there’s a sturdy set of 6 screws holding in the front element (versus 3 centering screws in the old version).

Take those out and the front element comes right out. There’s a strong molding ring around the seating areas and long screws used to hold it in place.

There are no adjustments on the front group. It’s permanently sealed in a heavy plastic mold that seats firmly into the lens mount.  If this lens drops you might crack a filter ring, but I can’t imagine decentering the front element.

Around to the Mount End

With the lens mount removed, the circuit board and flex cables show. Now this is the kind of thing that really makes no difference, but I do like to see someone took the time to design all of the cables so they fit neatly, not requiring glue to hold them in place and crisscrossing each other.

With the flexes disconnected and the circuit board removed we see the rear barrel mount. Again, I’m seeing that little bit extra that I’d hoped to see. There are multiple long screws holding everything in place, not the usual 3 or 4. This is all plastic, but it’s thick, heavy plastic, not the thin plastic mounts I worry about breaking or stripping.

Removing 6 screws, the zoom brush on the side (not shown), the zoom keys, the external barrel and rings come off in one single piece containing the switches  (sorry about the focus) . . .

Leaving all of the optics and the USM motor in a separate piece.

Another one of those really nice touches you’d never know about if you don’t take lenses apart. The distance scale isn’t just a piece of plastic glued to the inside of the barrel. It’s mounted to a metal piece that screws into place, and it’s much larger than it needs to be, which would help prevent light leaks through the distance window.

One more set of screws to remove (notice the screws are paired two images above – I’ve seen few lenses use two screws when one probably would be enough) and the USM assembly slips off in one piece again, leaving the entire optical assembly behind. The entire optical assembly (less the front group we took off first) is in Aaron’s left hand, the USM assembly and second barrel in one piece in his right hand. This is a very cool thing that I’ll discuss more in a minute.

The modularity of this disassembly is nice, obviously, for someone who has to do lens repairs. But the part I really liked seeing is on the central optical core. If you look below you can see the sliding helicoids with screws and nylon collars that hold the lens elements in place. The collars seem larger, heavier, and just tougher than the ones in the older version. Those collars were one of the things we saw wearing out on older copies and causing problems.

Also, do you notice the metal studs extending out from the middle barrel above? I hadn’t seen those on any lens like this before (sometimes you see a single one on a rotating ring). They keep the outer ring, with the USM motor, in proper place. But also they actually are stops that stop the barrel when the lens is fully retracted. In other lenses, the collars around the screws in the helicoids stop the lens motion. These metal stops should save a lot of wear and tear on the more delicate collars. Color me impressed. Again, this is just one of those nice touches that nobody will ever know about, but shows some design team was thinking, “How do we make this last a long time?”

Finally, I’ll give you a close-up that shows the adjustment mechanisms in this lens. You can see the two brass eccentric collars that adjust one of the rear elements for centering and tilt. They are far more protected than the front element adjustments on the old version. I can’t imagine a fall or jar knocking them out of place. Of course, the downside is whenever adjustment is needed, it’s going to require a lot of disassembly. But for almost everyone but us, that’s what factory service is for.

One last thing before we end. Look at that solid nylon ring around the screw above and compare it to a new and old ring from the old version below. The new ones certainly seem more robust.

New and heavily used helicoid collar from version I lens

Conclusion

Nothing but time can really tell how well this lens is going to hold up. Nothing but reviews of lots of copies by lots of users is going to show us how copy-to-copy variation will be. But it’s apparent to me that Canon has taken the time to design the lens well and build it sturdily. I totally agree, that for the price, it should be well designed and well built. But experience has taught me that is not always the case for a more expensive lens. I’m glad it is the case here.

Would I get one? Of course – I’m a resolution freak, a gear-head, and I don’t have a 24-70. I’ve just examined the highest resolving zoom lens I’ve ever tested and found it’s also built and designed superbly. I can’t walk away from that combination.

But is it a practical lens for you? Well, if you’re a working pro or a very serious (and well-healed) amateur I’d have to say yes. It is so good that if there were a 40 megapixel camera in your future, you’d want this to put in front of it. Plus it looks like it will hold up over the years better than its predecessor.

But at this price it’s not for everyone. If you prefer wide aperture primes to f/2.8 zooms, don’t shoot standard range a lot, or simply are not rolling in cash, you’d have to consider the price. There are excellent alternatives for a lot less money. Enough less money that you could buy another lens with the difference.

Whether you want to spend the money or not is likely to be a moot point for a while. Finding these is pretty difficult at the moment.

Roger Cicala

Lensrentals.com

September, 2012

I was already having a lens crush about the equivalent of teenage-girl-on-Justin-Bieber. I love to shoot at 135mm for long portraits and stealth street photography on SLRs (Canon 135 L, Nikon 135 DC, Sony 135 f/1.8) so this lens was very likely going to fill a niche for me. I was going to Imatest it and then take it home for some extensive long-term testing. You’ve seen all my long-term test write ups, right? No? Well, yeah, I generally don’t get around to doing them. Just keep the lenses in case I want to do a long-term test write up. Or something like that.

But guess what? When I opened up the new lens, there, right inside the center of the rear element, was a big chunk of Loctite (for those who don’t know, it’s a type of glue used to seal screws in lenses, dries to a plastic like finish, and occasionally a piece breaks loose inside a lens).

Now, before you decide to a) go major fanboy and declare to all who aren’t listening that this never happens to your brand, or b) sing the “quality control should never allow this to happen” song in three part harmony with the My Nation Assembles Better Than That Choir singing in the background, come back to reality.

This happens not infrequently, and in every lens brand. Not a week goes by that we don’t see it. A test shot wouldn’t have picked it up, it doesn’t show on images. Looking through the lens in regular room light didn’t show it. Looking through the lens against a smooth background using a couple of  halogen front lights shows it. It may sound like silly overkill, but I can assure from long experience that had we sent it out, the first renter would have done just such a check and complained about my quality control. So yeah, we overkill the QA thing a bit.

So guess what? One thing about Tyler’s somewhat-unique sources of supply: they don’t have a 14 day exchange policy. So Aaron and I had to go get that out. Which means a little lens disassembly and a chance to peak inside this bad boy.

 A Quick Internal Look

Compared to a lot of m4/3 lenses, there’s an immediately apparent quality difference: the lens is large with metal barrel and lens mount, both electronic contacts and rear baffle are screwed in, not just held in by friction.

The baffle removes first, after which you can remove the 4 screws that hold the lens mount in place, and the small screws that hold the electronic connectors to the mount.

Under the rear mount is what is shim. Thickness is likely adjusted to assure infinity focus since the entire lens is forward of this.

Underneath that we can see another bit of heavy-duty assembly. The barrel is attached with 4 large, long screws. These are of the size and number comparable  to what we see in “L” quality or “Pro” quality SLR lenses, and rarely in m4/3 lenses. Mirrorless cameras often have 3 small screws here. As an aside, that is Aaron’s thumbprint on the edge of the lens now, so if any of you are in law enforcement you may want to forward it to check for outstanding warrants.

Taking out the 4 screws lets us remove the rear barrel

Opening up the PCB and attached flexes controlling the electronics and exposing the AF motor at the top. Notice again, the PCB is attached with two large screws where most mirrorless lenses have one small one or even just a couple of plastic posts with the board held in by friction.

For fun, if we angle the flash just a bit on this shot we get a nice look at the color of the lens coatings used on this lens, which also brings Aaron’s fingerprints into clear relief.

Taking off the PCB and disconnecting the flexes gets us down to the core of the lens.

One thing that’s apparent, and nice, is that instead of screws and keys attaching the outer focusing ring to the actual focusing mechanism of the lens, Olympus has molded the part into the focusing barrel (red arrow). This would eliminate one of the possible causes of a jammed focusing ring we see fairly often.

Removing 3 more screws lets us remove the rear groups in one piece (you can see the bit of hardened Loctite is in there).

The remainder of the lens contains the diaphragm unit (notice the diaphragm spring), and the front elements.

Slipping the diaphragm control lever with a forceps demonstrates the very nice 9 bladed aperture ring which remains fairly circular even stopped down.

If you’re following along at home with your lens diagram scorecard, the 4 rear elements are in the removed group, the remaining elements are in the front section above.

Lens Diagram copyright Olympus

As we had been living right, apparently, the bit of loctite was easy to blow out from the side of the removed assembly and things put back together in a few minutes.

What’s the Point?

Not much really, except I like to look inside equipment and see how it’s built. (Some of you like to see, too.) This lens is built in much the same way that top-quality SLR lenses are made, which is not always the case for small, mirrorless camera lenses, as we’ve seen before.

Some people are put off by the price, at least from the discussions I’ve seen online. My perspective is that sometimes things are expensive because they’re worth it. This seems to be one of those times. The build quality is different than the majority of mirrorless lenses. The ones that are built like this are about this price range.

As far as image quality, I won’t repeat what has already been done more thoroughly elsewhere. But I will say the Imatest results are spectacular. Even wide open at f/1.8 the lens is resolving 880 / 765 Line Pairs / Image Height which is truly outstanding, especially in the corners. Stopped down to f/2.8 it resolves 1020 / 925. For me personally, it’s a focal length I’ll use a lot. Probably more importantly, it gives m4/3 users a high-quality short telephoto lens, something that has not been available without using adapters and giving up either small size or autofocus (or both).

Obviously, some of you will find it amusing that I’m writing about what a high-quality lens this is, considering we had to clean it out on arrival. Chances are if you’ve owned 10 or 20 lenses you’ve never had one arrive like this. Trust me, if you had 10,000 lenses you’d consider this an everyday event that affects every brand. It’s not common, but it happens.

It amuses me that a couple of weeks ago I wrote about the new 24mm and 28mm Canon IS primes that I felt were overpriced at around $900, yet I believe this $900 lens is well worth the price (if you can get it for list price). This lens is built better and is arguably sharper. More to the point, I can choose from among a lot of good SLR lenses in the 24 to 28mm range. For the micro 4/3 mount in the over 45mm range I can choose this one.

Roger Cicala and Aaron Closz

Lensrentals.com

July 2012

Even when things appear to be in the “bad lens” area, they usually aren’t. The majority of the time when a person thinks something is wrong with their lens, nothing really is.

Expectations are out of line or the learning curve of a new lens hasn’t been mastered yet. Even when there are real problems, usually they are simply autofocus problems in which the camera-lens combination just requires a bit of autofocus microadjustment. But every once in a while something is amiss with the optics of a lens.

I tend to write about “bad lenses” a lot because my major job here at Lensrentals is to check our stock, make sure the lenses are optically as they should be, and fix them if they aren’t.

In one post, I mentioned that it wasn’t unheard of for lenses to come back from repair with optical issues. That led to a lot of emails from people who didn’t understand how lenses could be less than perfect. My verbal explanations didn’t seem to help explain what was going on, so I thought perhaps showing you might clarify things.

Before we start though, the majority of this post is a Geek Level 4 article.

If you aren’t into the mechanics of how a lens works and what might cause problems with it, you will find the section on “Optically Adjusting the Lens” incredibly boring.  You might want to just skim over that section and then read the “What’s the Point” section at the end, which covers briefly why I think this stuff is important to anyone who owns a lens. If you don’t own a lens, then you’re definitely in the wrong place and need to hit the back button on your browser a couple of times.

Disclaimers

I want to be clear that this is NOT a how-to-optically-adjust-your-own-lens article. First of all, what we’ve learned, we’ve learned by reverse engineering.

We don’t have Canon’s, Nikon’s, or any other company’s in-house software and hardware that allows them to read lenses and predict necessary adjustments. We don’t even have the in-house manuals on how they actually do it. We’ve found methods that work for us, but that doesn’t mean it’s the best way or the right way. I’m certain it’s not the fastest way. It’s just the way we’ve figured out how to do it.

Even our “shade tree” methods require a lot of specialized equipment. We do our adjustments using repeated measurements with a $15K lens-test projector and a $12K Imatest optical testing setup. Even that isn’t ideal, and we have optical bench equipment ordered to augment our abilities.

There is simply no way to do this kind of stuff at home with some test charts or photographing a brick wall. And finally, every single lens has different places and methods for optical adjustments. The lens we’re doing here is one of the simpler ones.

Optically Adjusting the Lens

Identifying a Bad Copy

I’m going to use a Canon 24-70mm f/2.8L lens as an example, mostly because it’s a lens we know well and partly because adjusting it is pretty straightforward and the adjustments are easy to photograph. Not all lenses are as easy to work on. The copy we’re using for this demonstration has a fairly typical story: it was dropped, causing the filter ring to bend.

The ring is easy to replace but from long experience we know that dropped lenses often have problems that go well beyond the dent noticed on the outside, so all dropped lenses get optically tested before they’re put back in stock. This particular lens looked fine at 24mm but showed the pattern below when run through Imatest at 70mm.

Initial Imatest @ 70mm

From our routine testing, we know that a Canon 24-70mm f/2.8L should resolve around 700 line pairs / image height in the center and 560 lp / ih weighted mean, and this lens does neither. It also is very soft in the corners with several corners under 200 (250 is the absolute minimum). When we photographed a Siemens’ star chart with it, we saw a typical decentered pattern.

Optical Adjustments for This Lens

The Canon 24-70mm f/2.8L had a number of adjustments that can be made very easily. Several involve the front element, which is probably why it tends to get decentered with a fall or drop (like a lot of lenses).

With the filter ring removed, it’s apparent that the front element is a centering element: loosening the three front screws allows us to recenter the front element by sliding the element under the screws in whatever direction is needed.

Loosening the three front screws allows the front element to be centered.

Looking at the side of the front element, there are three screws that, when loosened, allow the element to rotate along a ramp, moving it slightly forward or backward from the rest of the lens.

Rotating the element along the ramp moves it forward or backward.

Another set of three screws on the front are surrounded by oblate (thicker on one side than the other) collars. Adjusting the collars tilts the lens forward or backward at that location.

Rotating the oblate collars tilts the lens forward or backward a mm or so at that location.

There is a similar set of collars located under the focusing ring that tilts the second lens group.

Performing the Adjustments

These adjustments are all rather precise. A movement of 0.5mm when centering the front element can make a dramatic difference, as can a turn of 30 degrees of an oblate collar or a movement of 1mm on the sliding ramp.

Since the lens seemed decentered, we started by loosening the three front screws and moving the element in the direction of the flare seen on the Siemens’ chart. This a fairly tedious process (since we don’t have an optical bench yet) that involves moving the element, remounting the lens to a camera to reinspect the image, and repeating until we seem to have good centering.

Once centering appears good as evaluated on the Zeiss-Siemens’ star chart, we retested the lens with Imatest and got the following results.

Imatest after front element centered

The centering has improved our corners somewhat (although not to acceptable levels) and actually lowered our overall resolution.

The charts I’m printing here only are showing vertical resolution at 13 samples, but in reality we’re checking vertical and horizontal resolution at 33 locations.  (I can’t reproduce those on images of this size – it just becomes a massive jumble of numbers.)

We also saw that vertical and horizontal numbers were much more equal after centering, which confirmed we were on the right track.

With the lens centered, overall resolution was still poor at 70mm, although good at 24mm (I’m not showing the 24mm results—trying to keep this post reasonably brief). From experience with a lot of dropped lenses, we felt adjusting the sliding ramp would be the best way to improve 70mm resolution. This can be done fairly quickly on the lens-test projector since we can evaluate sharpness in real time as the front element is adjusted.

We then repeated Imatest, which showed acceptable resolution numbers except for that there was still some obvious tilt, affecting the right side of the lens and especially the lower right corner.

We went back to the lens-test projector and adjusted the tilting collars on the front element, repeated the Imatest, and went back and adjusted some more.  Eventually, we got everything exactly where we wanted it, as the image below shows.

Final Imatest

Of course, we had to double-check the results at other focal lengths, to make certain the adjustments we’d made hadn’t done something negative at shorter focal lengths.

Since we had not needed to make adjustments to the second element we didn’t think there would be any problems at other focal lengths, and there were not. It’s not surprising that dropping the lens on the filter ring affected alignment of the front element, but not the second element.

To give some perspective, though, I’ve shown you only four of the actual 16 Imatest shots taken.

The entire adjustment from start to finish took about 90 minutes (including disassembly and reassembly), which makes this a fairly quick, straightforward adjustment.

With more complex lenses, it’s not unusual to spend three or four hours returning a lens to optical perfection—some lenses require major disassembly to make an adjustment, then partial reassembly to test that one tweak.

What’s The Point

There are several, actually. For some perspective though, let me assure you this lens is one of the simplest and most straightforward to adjust. Other lenses have up to a dozen (that we know of) adjustments that can be made.

In addition to the straightforward adjustments shown here, there are also multiple shims to adjust spacing between elements or between the lens and the camera (for proper infinity focus). In some cases, certain parts in the lens (like the rear mount) come in a variety of thicknesses, acting in the same way that shims would.

My first point is that given all of the adjustments that can be made with each lens, it is inevitable that each will be slightly different, even when “tuned” to its best resolution. That difference, though, is too small to see in a real photograph. It’s only apparent with a ridiculous degree of pixel peeping or using overly accurate test equipment.

If you notice in our last graph, above the right lower corner is still slightly softer than the left upper corner. Not only is that as good as we could make this lens, but it’s also far better than average. As I mentioned above, the average Canon 24-70mm f/2.8 resolves 700 / 560 with a minimum resolution of 250 lp/ih. This one now is 733 / 650 with a minimum of 363 lp/ih.

Could you tell the difference between the upper left and lower right corner or between this lens and an “average” 24-70mm?

Well, obviously if you have Imatest or an optical bench you can. Maybe, just maybe, if you have high quality optical test charts, a system to guarantee exact right angles to the chart, and you pixel peep at 100 percent you could tell the difference.

In a photograph? I doubt it seriously. On the other hand, you could tell the difference between this lens before and after adjustment at a glance.

The second point is that making these optical adjustments is time consuming and complicated. For us, the time and effort is financially worth it: if we don’t get the lens right, it can’t be rented and we’re going to part out an expensive lens. So spending three or four hours getting it right is worthwhile – we are going to loose over $1,000 if we don’t fix it.

If we were a repair center getting a flat $180( or whatever the fee is to fix a lens), spending three or four hours to optically adjust an optically complex lens it would make us go bankrupt pretty quickly. Factory service centers, given their equipment and training should be much better at this than we are — but unfortunately they aren’t.

So far this year, we’ve had over 30 lenses that failed optical testing when they came back from factory service and went straight back to the factory for them to try it again. Over a dozen went back to factory service twice, and in most cases we ended up doing the optical adjustments ourselves. In several we just ended up parting the lens out because they couldn’t be fixed (by the service center or by us). Keep this in perspective, though. That’s out of several hundred lens repairs on thousands of lenses. It happens, but it’s not common.

My third and final point is one that people do not like to hear. If you drop a lens hard enough to dent its filter ring (or the filter’s ring if you have a filter mounted) check it carefully even though it seems to work fine.

Certain lenses are likely to have something jarred loose inside affecting its image quality after a drop. Often, like this lens, adjustments can be made to correct it. At other times though, the drop has caused a slight bend in a barrel or other piece that must be replaced to restore optical integrity.

People often ask me what they should look at when buying a used lens, and dents or other signs of being dropped are very high on my list.

Roger Cicala and Aaron Closz

Lensrentals.com

July 2012

Addendum: OK, I have to admit I was busted in an email which said “Nice article, but I’m calling BS on the why you do it part: you mostly do it because you’re a gear-head and this is fun for you. We all know this.” I am. It is.

You see, children, once upon a time, maps came on a sheet of paper bigger than the windshield of your car but folded neatly into a little square the size of a Kindle. Maps couldn’t even say things like “Turn right in 200 yards”; you had to actually look at it and figure out where you wanted to go. But if you opened it up to look at it while driving, the map would cover the windshield and you’d have a wreck. On the other hand, if you weren’t driving, you rarely needed a map.

This presented quite a dilemma. Amateur travelers would steer the car with a knee while wadding the huge sheet of paper so they could see the area they were interested in. (This is what we did before we had texting-while-driving to distract us.) Real professional travelers had the skills of a one-armed Origami artist and could fold the map so the small part they were interested in was on top, while never taking their left hand off of the steering wheel. This was back when men were iron and ships were wood, though. Such skills do not exist today – except in certain little tripods that can be folded up to be about a foot long. But, I digress. A lot.

What was I talking about? Oh, yeah. Anyway, over time our nice, shiny, smoothly moving tripods tend to get jacked up a bit. Sand or salt-water gets in the legs and they don’t move smoothly anymore. Lever-lock latches don’t hold the legs quite as firmly as they used to and we find our carefully positioned tripod slllloooooowwwwly sliding to one side if we put a bit too much weight on it. Sometimes the internal locks and shims on the legs get knocked around and we have one leg that won’t slide all the way back into our tripod, or one section falls out entirely.

Luckily, tripods are probably the easiest things in a photographer’s kit to disassemble, clean internally, troubleshoot, and fix. So I thought I’d put together a little how-to-fix-it-up guide for those of you who have a gritty, sticky, loose, or just plain dirty tripod. We’ll start at the bottom and work our way up.

Changing Feet

Almost everyone knows it, but just in case you don’t, the feet on most tripods simply unscrew and can be replaced. Most manufacturers sell, or include, alternative feet so that you can use spikes in dirt or grass and rubber feet on concrete or rocks. But you can also simply buy some replacement feet when yours get worn out.

Cleaning and Repairing Twist Lock Legs

Most Giottos, Fiesol, Induro, Gitzo, and many other tripods use twist-lock legs. The designs differ very little and they generally function the same way. When a section of leg becomes stiff, gritty, or jams simply unscrew the lock all the way until it comes off of its threads and slides down onto the section of leg below it. There is usually some thick lubricant on the threads, as you can see in the picture below. Leave that alone if you can, but if there is a lot of sand or grit in it you may need to wipe it off and replace it when you reassemble.

As  you slide the leg section out, there will be a plastic lock bushing (in the center of the image above) that will come out along with the leg. As you pull the leg section further, you’ll feel a bit of resistance just as it’s about to come loose and will notice two half-circle nylon shims or bushings at the top of the leg (in the image below one is still on the leg, the other sitting on the desk).

Your tripod may vary a bit in shim appearance (they might be black, or a single shim that nearly goes around the entire leg, etc.) but the basic design is always the same. If your tripod leg was jammed and you don’t see shims come out with it, they probably came off and are inside the leg section above this. You may need to remove that section to find them because they’re often jammed up near the top of it.

At this point we can wipe all of the grit off of the shims and leg and clean them up nicely. You might also put a soft rag up into the leg section above to wipe any remaining grit left in it. You can probably just barely make out some dirt and grit on the upper part of the carbon fiber leg and the white nylon shims in the image above. That was what caused the leg to be gritty when sliding it in and out.

Before reassembling it’s a good idea to put just a little bit of dry lubricant, like powdered graphite, on the nylon shims and / or on the inside of the upper leg section. If you need to replace the lubricant on the threads, check your manufacturer’s website to see if they recommend a certain lubricant. If they don’t, we’ve found a waterproof, silicone-based lubricant like Novagard or Versilube seems to work fine. You can get any of the lubricants at Amazon, and, now that I think of it, it’s probably a good idea to get them before you disassemble the tripod. As with most lubricants, a little bit is enough; rub a bit of graphite on the shim with a fingertip, dab a bit of lubricant on the thread with a toothpick.

 respeReassembly is pretty straightforward. There is usually a hole in the side of the tripod leg that fits a plug in the nylon shim as shown below.

Hold the shims in place on the leg and insert. NOTE: with some tripods there is a guide in the upper leg that slides between the two shims as you insert (you can look or feel in the upper leg with your finger to see if there is). If that’s the case, line the space between the shims up properly or the leg won’t slide in easily.

After you slide the leg section a few inches into the section above, then slide the plastic lock bushing along the lower leg until it’s seated inside the upper leg (it’s halfway there in the picture below). Finally, you slide the twist-lock up, screw it back in place, and test that it locks the leg properly and the leg slides smoothly when it’s loosened. I say test it just because it sounds like a good idea. We’ve done this hundreds of times and never had one that wasn’t working just fine after reassembly.

Of course, you’ll have to repeat this for as many sections of the leg as have problems and on as many legs as have problems. I suggest, at least at first, you do one section at a time starting at the bottom section. The shims and bushings are specific sizes for each leg section and getting them confused means a lot of trial and error during reassembly.

 Cleaning and Repairing Lever Lock Legs

A lot of Benro, Cullman, Manfrotto, and Oben tripods use lever lock legs. Most use two different fasteners for each section: one that holds the section on the leg, the other that adjusts tension of the lever lock. Depending on brand you may need a nut driver, hex key, or both (like the one in the picture below) to disassemble these. Some smaller Bogen and Manfrotto tripods use a different type of lever lock that has a center pin that must be driven out with a hammer and awl. If you want to remove the lever lock on this type of  tripod, they have a video of how to do it here: www.bogentripodparts.com/repairs.htm

By far the most common thing you’ll want to do with your lever-lock tripod is adjust the lock tension. It may be stiffer than you like early on, or may get too loose and not grip the legs tightly over time. It’s simple to do: simply put the right tool (hex key or nut driver) on the bolt with the lever in open position, and slowly tighten it while flipping the lever open and closed until it has just the tension you want.

It seems a little less common for lever-lock tripod legs to get grit and sand inside, but they can. Disassembly is pretty similar to that for twist-lock legs, except for needing tools to remove the lever locks. Remove both of the clamping screws / nuts. There is a spring in the lever-lock side of the assembly but for the vast majority of tripods it will not come out when you remove the lever and nut (even if it does, it’s easy to put back).

You may need to twist or rock the locking assembly just a bit and then slide it down over the lower leg. In the picture below you can see some salt residue had gotten under the lock from the tripod being used in or near salt water.

There will be two semicircular shims (or a single nearly circular shim) as shown below, but no lock bushing when you remove the lower leg section.

You can clean things off now, just as you did for the twist-lock leg. You won’t need any silicone grease since there is no twist lock, but a bit of powdered graphite rubbed inside the upper tube or over the outside of the shims before reinserting the lower section helps keeping things sliding smoothly.

Next it’s a simple matter to replace the lever locks and bolts where they came from. One “learn from my mistakes” hint: make sure you line the lever up with the ones above it so the latches are all in a nice straight line when the tripod is collapsed. Otherwise you get to loosen and tighten them again.

Removing the Legs

It’s actually pretty rare to have to remove the legs or work at the center of the tripod where the legs come together.  Every tripod is a bit different in this area, but simply looking around a bit makes it pretty apparent how the legs can be removed. In smaller tripods, like the one below, it’s often as simple as a couple of hex keys or bolts holding each leg in place.

With larger tripods it’s often more complex, though. One common arrangement is a clam shell of two plates that can be taken apart. . .

 . . . . to give access to the leg mounts.

If there’s a center post tension knob like the tripod above, there will be a spring inside, but as long as you don’t drop it reassembly is pretty straightforward. Probably because there’s a lot less movement up at the leg mounts, there seems to be little that ever goes wrong here and it’s rarely necessary to remove them except to replace a broken leg.

Center Posts

Center posts are rather simple things and rarely require any maintenance: if sand or dirt gets on them, you wipe it off, run the post up and down a couple of times, and wipe it off again. Very occasionally something will get into the friction lock of the center post. While removing them is usually straightforward, almost every single one is different. If you look around, though, you’ll almost always see a way to remove the base plate (usually a set screw or hex screw is removed, then the plate either pulls off or unscrews). Once the end plate is off  you can remove the center post.

Other times, there is an obvious twist-lock around the center post that will unscrew just like on a twist-lock leg. Generally there is just a one-piece shim in this kind of arrangement.

Replacement Parts

There is a great deal of variation between the different brands regarding ordering replacement parts. Bogen-Manfrotto not only sell parts directly and easily from BogenTripodParts.com, they offer photos of the various parts for each tripod so you can easily get the part number you need. If you’re a do-it-yourselfer, that website alone may steer you to a Bogen or Manfrotto tripod. Gitzo also has a really great parts supply website at www.gitzo.com/service/service+repair/. You just type in your product number and it takes you to a schematic that provides all of the part numbers, which you can order online.

I haven’t found simple online parts ordering for any of the other brands. In many cases, though, if you email customer support at the manufacturer of your tripod, they will try to get a part for you. It’s often helpful to have a picture of the part you can send them. You can occasionally find parts on eBay. You may also find broken tripods for sale there at very low cost.  Here’s a hint: if you buy a tripod with one bad leg you can use one good leg to fix your tripod, and sell the other good leg for almost what you paid for the broken tripod. Or keep it, just in case.

Roger Cicala and Aaron Closz

Lensrentals.com

June, 2012

All photos courtesy Aaron Closz. All fingers in photos courtesy Roger Cicala