There are occasionally times that large dust specs very near the rear element are visible in an image, though. There also is the very real issue of resale value; a dusty lens tends to bring a lower price than one without much dust. The right answer in these cases is “send it in for factory service, they’ll disassemble it and clean it.” Doing it yourself is risky.

After I give all of those answers, a lot of people tell me they have an old lens no longer under warranty, not worth the cost of sending it in for factory cleaning, and they are really handy and want to do it themselves. For those people, we’ve put up this post showing how to get dust out of some fairly easy to reach locations.

More Than the Usual Warnings Apply

1. If you open a lens you have completely voided the warranty. Don’t do this on any lens still in warranty.
2. You can change a dusty lens into an unusable lens if things go wrong. And things do go wrong.
3. If you mess up and strip a screw or tear a flex, factory service may (or may not) even attempt to repair it. If they do decide to repair it they will charge an additional “tampered with” fee in addition to the service charge. It is reasonable for them to do so. It’s way harder and more time consuming to repair a lens someone has messed up.
4. If things go really wrong and you can’t reassemble the lens, nobody, and I mean nobody, will put it back together for you at any price. I get asked to do it occasionally, and I won’t even consider it. It’s one thing to reassemble a lens I’ve carefully disassembled, keeping the parts organized. It’s another to try to put together a 3 dimensional jigsaw puzzle of pieces.
5. Chances are you really don’t need to do this anyway. Even a moderate amount of dust rarely has any effect on images.

Now, if you’ve read all of those warnings, have an appropriately old, out of warranty lens, and are certain the dust needs to be removed (even though it probably doesn’t), read on.

Tools Needed

You’ll need a good quality, J. I. S. (Japanese Industrial Standard) #00 or #000 screwdriver. Lens screws look like Phillips head, but they aren’t. A Phillips screwdriver may work but is far more likely to strip a screw. Read warning #3 – a stripped screw is a really bad thing.

You’ll really prefer a magnetized screwdriver so pick up a magnetizer when you go shopping for tools at Amazon or wherever.

You’ll also need a rocket blower or electric blower that does NOT use canned air with propellant. Getting propellant in the lens is way worse than dust. (Yes, I know That Guy used can air and his lens is fine. You might get away with it 20 times before you ruin a lens.) Plus, warning #3 will apply if you try to send the lens in for service with propellant coating the lens elements.

Finally, you’ll need a well lit workplace with room to keep screws and parts organized. My ‘well lit’ may be different than yours but I use three 100 watt halogen desk lamps on flexible arms.

Today’s Lenses:

Below are the lenses we’ll show how to dust out today, with lenses that are similar listed in parenthesis. Just click the lens to go straight to that section of the article.

1. Nikon 24-70 f/2.8 AF-S (Many Nikon “D” primes)
2. Canon 17-55 f/2.8 IS(Canon 24-105, 24-70 f/4 IS, 24-70 f/2.8 II)
3. Canon 85mm f/1.2 L
4. Canon 85mm f/1.8 (Canon 100m f/2)
5. Canon 70-200 f/2.8 NON IS (Canon 70-200 f/2.8 IS I and II)
6. Canon 100-400 IS L (Canon 28-300 IS L)

Here We Go

I’m giving examples of very easy to moderately easy places you can get dust out of in certain lenses. PLEASE DON’T EMAIL ME ABOUT HOW TO DUST A LENS NOT SHOWN HERE. Most lenses have front or rear centering elements that if removed, require factory recentering and recalibration.  You can’t do that at home. 

Nikon 24-70mm f/2.8 AF-S Rear Dust

Also applies to: many Nikon “D” prime lenses.

Difficulty: This is the easiest lens dusting of all.

As a rule, Nikon lenses are more difficult to get into, but the 24-70mm is an exception. It’s probably the easiest lens to remove rear dust from because the rear glass is a separate, fixed element that can be removed with just 3 screws.

Three small screws attach it to the side of the lens mount. Do NOT remove the small screws holding the electrical contacts in place.

Once the screws are removed you can remove the rear element – lift it out or simply turn the lens upside down and let it fall into your palm.

Blow the dust out and you’re done. Notice the spring for the aperture lever at 2 o’clock inside the lens – don’t mess with it.

When you put the element back in place, be sure to line up the slot for the aperture lever (red arrow below). Bending the lever is probably the only risk with this one. Don’t forget to replace the screws. I did that once (that’s why I don’t take phone calls during the workday – I forget where I am in a disassembly).

Canon 17-55 f/2.8 IS EF-S Front Dust

Also applies to: Canon 24-105 f/4 IS, 24-70 f/4 IS, 24-70 f/2.8 II (although these have more screws holding the front element in)

Difficulty: Very easy

Most of you interested have probably seen this from a post I did a couple of years ago, but we’ll try to be a bit clearer with this one. It’s nearly as easy as the Nikon 24-70.

Start by using some sharp forceps or a small screwdriver to peel up the makeup ring. It’s stuck on with sticky adhesive and will stick right back on if you don’t set it sticky-side down on the counter.

With the makeup ring removed you’ll see the three screws that hold the front element in place. At each screw location there are three possible holes for it to go in. You’ll want to remember which set of holes the screws go in (left, right, center) on your lens. The location of the front element will be apparent from the marks the screw head has made.

Here’s a front view with one screw removed. You can see the three possible holes (you might not in your lens, depending on the placement of the front element one or two may be outside of the slot). It’s important that the lens go back in exactly the position it was in before. In this lens the left (most clockwise) hole is used and you can see the mark the removed screw left in the front element. If you can’t see it clearly, or you’re OCD like Aaron, make a small scratch.

Once the screws are removed the front element comes out. If you don’t have a fancy suction bulb just drop it out into your palm. It’s fairly large.

The front element chamber is pretty large, but you’ll be amazed at how that huge dust speck is really quite tiny without the front element to magnify it. BTW – the three screws at the bottom of the chamber hold the front barrel in place. As long as you’re here you might make sure they’re tight. The odd shape at 11 o’clock is where this group attaches to the focusing ring key.

If you don’t have a suction bulb thingie, the simplest way to replace the front element after the dust is gone is to hold it upside down and put the lens down over it. After turning it upright you can rotate the front element to proper position before replacing the screws.

Canon 85mm f/1.2 Rear

Difficulty: Easy

It’s very easy to get rear dust out of the Canon f/1.2 prime lenses (the front is another matter entirely).

The 4 lens mount screws are removed. They are often glued in so be careful about stripping these — if the screw doesn’t come out fairly easily then quit.

Once the screws are remove you can tilt up the rear element on the side away from the electrical contacts and blow the dust out. Important: just tilt it. If you tear the contacts you will be in for a major repair cost.

Canon 85mm f/1.8 front and rear

Also applies to: Canon 100 f/2.0; Canon 50mm f/1.4

Difficulty: moderate

When these lenses get dust it tends to be on either side of the central group, so you generally need to do both the front and rear. This one is more time consuming and a bit more difficult than the previous ones, but still fairly straightforward.

Rear

Start by removing the two small screws that hold the electronic contacts to the rear mount.

Then the 4 larger screws that hold the rear mount to the lens.

Once those are removed, lift the mount up just a bit on the side opposite the contacts, put a finger under the mount and while holding the mount firmly in your other hand use the finger to pop out the plastic rear baffle.

With the plastic baffle out, just slide the contact assembly away from the metal ring a bit (there a small post in the back that inserts into a hole in the metal ring) and remove the ring.

Now you can see the PCB and the rear element is exposed. The rear group has some notches around the plastic rim — you can see one lined up above the ’85′ on the lens barrel. Remember where it lines up (or make a tiny mark lined up with some landmark). You’ll need that later.  Note the flexes and soldered wire attaching to the PCB. Your goal from this point forward is not to pull them.

The rear element unscrews counter-clockwise several turns (you wanted to line up those landmarks so you know you have it fully tightened during reassembly). If you have a flat spanner wrench you can use that to unscrew the lens.  But then again, if you have your own spanner wrench you probably don’t need me to show you how to do this.

Often you can unscrew the rear element by using your thumbnails in a couple of the slots in the rear element. One of those rubber ‘jar opener’ sheets works really well, too. Just remember – DO NOT PULL ON THE FLEXES OR WIRES while you do this. If you tear them, the lens is basically junk.

Once the rear element is unscrewed, lift it out, blow out the inside group and clean the rear group.

Reassembly is the reverse, of course. When you put the lens group back in, make sure it’s level and screws in with little resistance. If you cross-thread it the lens will be badly decentered. Tighten until you reach the mark you were at originally.

When you put the rear mount back on, I find it best to put the screws holding the electrical contacts in first (use the post in the contacts to line it up properly, then put in the screws) then put the mount screws into the lens. Finally pop the plastic light baffle back in.

Front

There are 3 screws that hold the front barrel cover onto the lens. Before you remove them make a mental note of which way the cover lines up (the distance window is a good landmark) so you put it back on correctly. It will still work fine if you put it on wrong, but someone (likely a future buyer or repair shop) will notice you’ve put it back wrong.

Once the three screws are removed the front barrel slides right off.

Inside the front barrel is some dust-catching sticky felt. Might as well clean that off while you’re here.

The front element is held on by 3 screws. As usual, you’ll find reassembly easier if you mark how the lens element should line up when reassembled.

Under 1, 2 or all 3 or the lens screws you will notice small adjusting screws that the factory used to set the tilt of the front group to zero. Don’t touch them.

Once you’ve removed the three screws holding the front group in place it lifts right off. Blow dust out from inside and under the back glass of the front group and put everything back together.

This one is a little more time consuming than the previous ones, but still pretty straightforward.

Canon 70-200 f/2.8 Non IS front

Also applies to: Canon 70-200 f/2.8 IS and IS II (with some modifications)

Difficulty: Easy, but you won’t get out all of the dust.

In general, getting dust out of a 70-200 f/2.8 lens is difficult, but most of the dust right under the front element can be removed fairly easily. Getting it all out, or getting out deeper dust, requires removing elements that require recalibration.

Really all we need to do is remove the filter ring barrel. To access it first either fold down (or remove) the focusing rubber. This exposes three holes in the focusing ring. Rotate the ring until the holes line up with the three screws (as shown below) that hold the filter ring barrel on. The IS II version has 5 screws rather than 3.

Remove the screws and the filter ring slides off. As always, you’ll want to remember how it aligns when you replace it (the red ultrasonic lines up along the distance scale window).

There is a layer of dust-protection / weather sealing tape around the inner barrel. Find the end and take it off.

This allows you to access several openings in the inner barrel through which you can blow air to get dust out of the first chamber. Again, you won’t get every speck of dust out, but you can get most of it.

Canon 100-400 IS L front

Also applies to: Canon 28-300 IS L

Difficulty: Moderate

Let’s get this out first: You may or may not be able to get into this lens with simple tools. The screws are quite tight, glued in, and rather easy to strip. So try it, but if you find you are having trouble with the screws, quit before you strip them. You’ll need to apply a lot of downward force as you loosen them. If it wasn’t for the screws, this would be an easy one to do.

First a shot to show how various barrels line up when you reassemble.

The first step is to remove the silver name ring. There are three very small slotted screws holding this in place.

You’ll need a very small electronic flat head screwdriver (1.5mm or less) to remove these screws.

Once they are out you slide the silver name ring and the red “L” ring over the end of the lens. Under the name ring are three thick screws that hold on the filter barrel.

These are the screws most likely to strip. A very good screwdriver and a lot of downward pressure are the keys to removing them. If you want to be aggressive you can put a drop of alcohol on top of the screw and let it soak in to soften any glue, or touch the screw with a soldering iron tip to heat it a bit. I’d really advise, if they don’t come out easily, to just put the name ring back on and not worry about the dust unless it’s horrible.

Once these three screws are removed, the filter barrel also slides off of the end of the lens.

Underneath this is the focusing barrel – a single tube attached to the focus and smooth-tighten rings. It is held on by a single screw with a small brass color attaching it to the thin inner focusing ring. When you remove this hold things close to your worktable. These two parts fall on the floor and you probably won’t find them again.

With the screw removed you can slide the focusing barrel right off, too.

Once the outer barrels are off, you can pull on the front of the lens (not the plastic cosmetic ring on the very front, the sides, which are black metal) and extend the lens. This exposes all of the helicoid slots of the inner barrel. You can use your rocket blower at various locations and get most of the dust out of the front of the lens. (Just in case you are tempted, the element inside at the bottom of the front barrel is the IS unit. Don’t touch it. Don’t blow on it too hard.)

Let the barrel slide back into the sleeve of the lens, put things back in reverse order, and you’re all done. I will say reassembly is usually much easier than disassembly with this lens.

Conclusion

If you’re handy and have an appropriate lens, hopefully this will help you out. I can’t emphasize enough that dust really doesn’t impact images unless it’s really bad and you shoot stopped down. But for whatever reasons, everybody wants their lenses clean. This should help you accomplish that with at least a few of them. For a while. It will be back.

I want to emphasize again, these are the easy ones. Cleaning middle elements in any lens, and cleaning any elements at all in a lot of lenses, is complicated, time consuming, and has a lot of risks.

Roger Cicala and Aaron Cosz

Lensrentals.com

May, 2013

All images copyright Roger Cicala, 2013 except a couple that are copyright Aaron Closz.

All hands in images furnished by Aaron Closz, 2013 except a couple furnished by Roger Cicala.

Images may be reproduced IF you include credit and the article includes a link to this post.

I’m never one to worry much about lens dust. I’ve written about why you shouldn’t worry about some dust in your lens. But the color bombs they throw out at Color Runs are different. In the last month we’ve had over 20 lenses and several cameras nearly ruined by these things. For what it’s worth, all of the renters tell us they really weren’t near any of the major ‘color bombs.’

Here’s a few pictures from a brand new lens that returned after its first rental — at a Color Run. These pictures are, of course, after the lens was cleaned externally. All of that dust is inside the front and rear elements.

Now a few dust specs rarely cause problems, but this kind of dust affects light transmission and contrast, as well as causing fascinating flare (in pretty colors). The color dust is very fine, tiny specs, made to stick on people as the run by (I’m still trying to figure out why someone thought this was a good idea).  Because of this, the lenses’ weather sealing, front filters, etc. don’t even slow this stuff down. It’s throughout the entire lens stuck on every element, on the gears and helicoids, and in the mirror box of the camera too. And yes, that includes pro-level lenses on pro-level cameras, all of which are supposedly weather sealed. As an added bonus, it doesn’t blow out like regular dust. It must be wiped off.

Here’s a look at the inner rim after the front element was removed.

Here’s the front of group 2, nice and deep inside the lens (excuse the lights, this is a quick post just using worklights).

And here’s one of a dozen Q tips I used to clean out around the focusing gears and helicoids. Remember, this was a brand new lens only used for this one shoot.

The end result for this lens was complete disassembly and cleaning. This was a fairly lucky one – it’s a lens that we can disassemble and clean without requiring factory readjustment. For a lot of lenses that’s not an option.

A number of lenses, including Canon L’s and Nikon Pro lenses had to go to the factory, and at least one has been given the “financially not feasable to repair” sticker. Your guess is as good as mine as to whether they cover it under warranty or not.

You know what I’d probably find more interesting than the photos of what the insides of lenses look like after this? What the inside of the runner’s lungs look like. All my medical training leaves me curious about that kind of thing.

Addendum – here’s a bonus picture. A Sigma 8-16mm with the barrels removed so you can see how pervasive the Fun Run dust was throughout the entire lens. The dust around the mount side of the lens is so thick that it’s blocking the AF motor from working properly and it’s so caked into the lubricant that the helicoids don’t zoom normally. This will have to be completely disassembled and cleaned piece by piece.

Roger Cicala

Lensrentals.com

May 2013

BTW – Because I’ve already been asked: this won’t be covered by the rental damage waiver going forward – it’s considered negligent use of equipment just like when salt spray soaks the camera on the beach.

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

The company’s other offerings have all had excellent optics. Construction quality has been rather iffy, and getting one repaired nearly impossible. On the other hand, good optics at prices like they offer makes the build-quality trade off more than acceptable.

I should mention I’m a bit of a Rokinon fan. I own their 14mm because at $379 I think it’s an insane bargain for a very sharp lens. For that price, compared to $2,300 for a Canon 14mm, I’m more than willing to give up autofocus, accept some barrel distortion, and consider it disposable. If it breaks getting a new one won’t be much more expensive than the standard repair cost for a Canon 14mm and less than the repair cost of a Nikon 14-24.

But a tilt-shift is a lot more complex than a simple prime lens, and the RokiBowYang 24mm tilt-shift costs a lot more than their 14mm. So I’ll admit that going in I was a bit skeptical of this lens.

Look and Feel

The first noticeable thing when comparing the Canon 24mm f/3.5 TS-E II, Nikon 24mm PC-E, and Rokinon 24mm TS lenses is the weight.  The Canon weighs in at 780 grams (27.5 ounces), the Samyang at 680, and the Nikon at 730 grams. The Samyang does NOT come with a hood, which the other two have, although they are very shallow hoods that probably aren’t particularly effective.

I think it important to note that the Rokinon has only has 6 aperture blades, compared to 8 for the Canon and 9 for the Nikon. While the Rokinon aperture is round when wide open, stopping down, even a little bit, clearly changes it to a hexagon.

One other thing I noted as soon as I used the lens: the Rokinon has smaller plastic knobs for controlling tilt-shift and locking. The small lever that allows you to rotate the lens on its base and the tilt and shift axis is rather thin plastic (compared to metal on the other lenses) that flexes about 30 degrees when pushed. That makes me a bit nervous; it certainly seems like it could break off without too much pressure.

As far as function, though, the Rokinon gives everything you would ask: 8.5 degrees of tilt, 12 degrees of shift, rotating base and the shift and tilt axis can be rotated so they are aligned or at right angles to each other. The Canon 24mm  TS-E can match all these functions, but the Nikon can’t match the rotations.

Imatest Results

Unfortunately, Imatest results can only be obtained with the lens in straight position, so we can’t compare tilted and shifted. Plenty of lens reviewers will be comparing tilted and shifted images, soon, though.

We tested 4 copies in Canon mount on our Canon 5D Mk II test cameras in the usual fashion. The table below shows the results for the Rokinon versus the Canon 24mm f/3.5 TS-E L. The numbers represent MTF 50 in the center, averaged across the entire lens surface, and the average of the 4 near-corner areas.

	Center	Average	Corner Average
Samyang 24mm f/3.5 TS-E	730	560	455
Canon 24mm TS-E f/3.5	910	775	520
Canon 24-105 f/4 at 24mm	840	690	490

It’s a bit unfair to compare the Rokinon with a $2,000 lens that is widely recognized as one of the sharpest tilt-shifts made, but that’s the most direct comparison. Since most people probably haven’t shot with the Canon 24 TS-E, I included the resolution numbers for the Canon 24-105 f/4 IS just to give a widely known comparison point. Put simply, the Samyang 24 TS-E resolution is adequate – not great but not awful, either.

I thought measurements against the Nikon 24mm PC-E lens might be more even since the Nikon is a much older design that is probably due for a makeover soon. We did our Nikon-mount tests on a D800, so the higher camera resolution would be expected to give significantly higher MTF 50 numbers than the Canon 5D II. (In previous tests we’ve done, the same lens will have an MTF from 15% to 20% higher on a D800 than a 5D II.)

Unfortunately, one of the 4 Nikon-mount Rokinon copies we received was badly decentered, so we only averaged the test results for the other 3 copies, averaged in the table below.

	MTF 50 Center	MTF 50 Average	MTF 50 corner
Samyang 24mm TS	800	640	500
Nikon 24mm PC-E	990	770	490

The Nikon lens clearly resolves a bit better in the center than the Samyang, although in the corner area things are pretty even.

Let’s all remember, though, that these are tilt-shift lenses. Resolution is important, of course, but absolute resolution is not the primary reason we choose a tilt-shift lens, so these tests may be less important than they would be for a standard prime lens. Unfortunately, as I mentioned earlier, our testing tools don’t let us make comparisons with the lenses shifted and tilted — it’s theoretically possible but so many new variables are introduced I wouldn’t trust the results.

The Samyang also falls behind the others on distortion, with 2.3% barrel distortion compared to 1.4% for the Nikon and 0.9% for the Canon.

Stopping Down Aperture

Comparing the lenses stopped down provides some interesting additional information.

The Canon and Nikon tilt-shifts improve only slightly stopped down (for real world purposes the Canon is really identical from f/3.5 to f/8; the Nikon gets a bit sharper in the corners by f/5.6). The Samyang, however, improves quite a bit stopped down.

On the 5D II it never quite catches the Canon lens’s peak resolution, but at f/11 they are identical. (The Canon lens is not getting any sharper from f/8 to f/11, so all we see is diffraction softening. The Samyang is still improving optically, more than enough to offset the diffraction softening.) Compared to the Nikon lens Samyang has almost identical resolution at f/8.

This is a rather important point. A landscape shooter who plans to use tilt function to maximize depth of field and shoot at small apertures should find the Samyang very competitive with the brand name lenses. Someone who plans to shoot at wide apertures will almost certainly notice the difference.

A Very Few Images

Obviously this isn’t a review — I’m a tester not a reviewer. I was able during the few hours it hasn’t been raining this weekend to take a few shots with the lens on a Canon 6D. They may give a little idea about untilted/unshifted image quality and a chance to look at out of focus areas.

Evaluating the out of focus areas, it appears the lens has both longitudinal chromatic and spherical aberration wide open, which is probably why it sharpens up so nicely stopped down. If you want to see 100% jpgs, you can do so HERE.

Conclusions

Obviously this isn’t a full review (that’s not what I do), but hopefully will provide a little information for those considering this lens.

I consider it reasonably priced for the image quality it delivers, but not a screaming bargain by any means. (I consider the RokiBowYang 14mm a screaming bargain.) But, since there is very little competition in the ‘reasonably priced’ tilt-shift lens category, I expect it will sell well.

For those who primarily shoot this kind of lens stopped down, it may be a very good choice. Wide open it’s still acceptable, but the difference between it and the Nikon and Canon versions are going to be noticeable at f/3.5.

I am concerned about the reliability issue, especially given the difficulty in getting RokiBowYang lenses repaired in the U. S. I’ll be tearing one down in the next few days and hopefully looking at the build inside will help alleviate (or confirm) those concerns.

Roger Cicala and Aaron Closz

Lensrentals.com

May, 2013

Since we got a nice bunch of the A1 version lenses in yesterday, we thought it would be worthwhile to do a bit of comparison with the older version. For those who haven’t had the pleasure used the original Sigma 30mm f/1.4 lens, it was something of a love-hate relationship. The original 30mm was small, sharp, and inexpensive; a perfect combination for those shooting a crop sensor camera. Unfortunately, it had the somewhat dubious combination of being rather inaccurate to autofocus, yet extremely difficult to manually focus because of its inaccurate MF ring. There was, perhaps, a bit more copy-to-copy variation than many of us found acceptable.

Sigma’s new version of the 30mm APS-C only lens, would, we hoped, eliminate those negatives. It might even be dramatically better than the original version optically. The original wasn’t a bad lens at all, but the recent Sigma 35mm f/1.4 lens had most of us anticipating something impressive with the new 30mm, too. But before we get to the optics, lets take a look at the two versions.

Tale of the Tape

	30mm EX DC	30mm DC HSM
Elements / Groups	7 / 7	9 / 8
Aperture blades	8	9
Min. Foc. Dist. (ft)	1.3	0.9
Filter size	62	62
weight (oz.)	15	15
Price	$289	$499

So the new lens gives us a new optical formula, an extra aperture blade, and closer minimum focusing distance to go along with a higher, although still reasonable, price tag. It also comes with the much improved outer coating that doesn’t peel off like the one on the original lens and a HSM (hypersonic) motor that should improve AF speed and perhaps accuracy.

After putting the lens on a camera the build difference is immediately apparent. The lens feels more solidly built, particularly the hood. Most immediately apparent, though, is that the manual focus ring turns smoothly and accurately, which is not at all the case with the gritty, jumpy, inaccurate MF ring on the original version. Did I mention I didn’t like the original MF ring? To paraphrase Shakespeare, “I would beat thee, but that would only infect my hand.” The new one, though, is a pleasure to manually focus; smooth and accurate.

Optical Evaluation

I don’t usually put optical formulas and MTF charts in these posts, but I’m going to make an exception today. Because the lenses look so similar on the outside and have such similar names, I think it important to demonstrate how different they are inside. Here are the optical formulas for the two lenses.

I need to mention that we tested these lenses on a Canon 7D. Results would be slightly different on other cameras so please try not to make comparisons to, say, the Sigma 35mm f/1.4 tested on a Canon 5D Mk III. Yes, I know you’re going to anyway, but at least now I can say, “I told you so.”

Anyway, we compared the 8 copies of the 30mm A1 that came in today with 6 copies of the 30mm f/1.4 DC that were on the shelf. As usual, average MTF 50 across the entire lens is plotted on the vertical axis, center MTF 50 on the horizontal, both in Line Pairs / Image Height.

As you can see on the vertical axis, the new version (blue dots) has slightly higher overall (average) resolution, while the older version (red dots) has, perhaps, slightly higher center resolution. (The center difference is pretty minimal and I doubt you could pick it up even pixel-peeping.) The difference away from the center is a bit clearer when presented as a table with corner values included.

	Center MTF 50	Avg MTF 50	Corner MTF 50
Sigma 30mm f/1.4 HSM A1	600	490	340
Sigma 30mm f/1.4 EX DC	605	450	260

The lenses, at f/1.4, are about identical in the center, but the new version is significantly better in the corners.

Let’s look at how that changes as we stop down.

The new version starts of sharper in the corners and the corners steadily improve to f/5.6. The old version starts off softer in the corners and improves less as we stop it down. Its corners peak at f/8, but never get nearly as sharp as the new version does.

Conclusion

Like a lot of people, I was hoping for a crop-sensor version of the Sigma 35mm f/1.4 full-frame lens; an amazingly high-resolution optic. This lens isn’t that good optically. It’s a very nice lens with good resolution and excellent corner performance. If corner performance is important to you this lens is a significant upgrade. If you are more interested in center resolution, than optically it’s not better than the original.

However, I’d still consider this a worthwhile upgrade for a number of reasons. Build quality is far better. The new lens can be accurately focused manually, something that live-view shooters like myself found was difficult to do with the original. I can’t speak for autofocus accuracy yet, but the Sigma USB dock,which now has a release date of early May, will allow us a degree of microfocus adjustment not available with other lenses. The dock is fully compatible with the A1 lens. To me, that’s worth the price of the upgrade right there.

Roger Cicala and Aaron Closz

Lensrentals.com

April, 2013

Unlike the CP.2 lens, the ZE and ZF mount Zeiss 135mm lenses have normal photography housings. The manual focus throw is not nearly as long as with the cinema lens, but it is very smooth and the lens focuses beautifully. With its solid metal housing, the Zeiss weighs in just over 2 pounds compared to 1.65 pounds for the Canon. The Zeiss has a 77mm front element compared to 72mm for the Canon, and 9 aperture blades compared to the Canon’s 8. There’s a bit of price difference, too, with the Zeiss listing for $2,122 and the Canon $989 at the moment.

Imatest Results

We had 8 copies of the ZE 135mm f/2 to test today — not enough to give absolute limits of variation but enough to at least give us a good suggestion. I’ve shown the Imatest MTF 50 results (in Line Pairs / Image Height on a Canon 5D Mk II) at f/2.0 below. As you can see this is a nice, tight grouping of results.

Compared to the average (mean) MTF50 values for the Canon 135mm f/2L, the Zeiss is better wide open across the frame, as shown in the table below. That’s very impressive as the Canon is one of the sharpest lenses around.

	Center MTF 50	Avg MTF 50	Corner MTF 50
Zeiss 135mm f/2	945	840	745
Canon 135mm f/2	800	710	640

As we stop the aperture down, though, the Canon catches up quite quickly. As shown in the graph below, the Zeiss slowly sharpens up steradily through f/5.6 on the Canon 5D II, with the corners reaching their maximum at f/8.

The Canon lens peaks at around the same aperture, but resolution increases to a greater degree as we stop down. By f/5.6 the lenses are virtually equal in resolution.

Summary

The Zeiss 135mm f/2 APO-Sonnar is a superb lens. It has one of the highest resolutions we’ve tested overall and the corners are amazingly good, even wide open. You definitely pay for what you get, though. The Canon 135mm f/2 is a superb lens and while it doesn’t have quite the resolution as the Zeiss wide open, it is less than half the price and autofocuses. (The 135mm f/2 is always on my list of the best value lenses available.)

Possibly in reaction to the Zeiss 135mm hitting the streets, a very widespread rumor has appeared that Sigma will announce a 135mm f/1.8 OS Art Series lens later this year. That’s exciting, but the key word here are ‘rumored’ and ‘announce’. While Sigma is generally fairly quick from announcement to release, that still sounds like a lens that won’t be available until the end of 2013 or early 2014. Assuming the rumors are true.

For video shooters, particularly, this lens is going to be a superb tool. Photographers wanting the very best will be interested, too. The optics are as good as it gets.

Roger Cicala

Lensrentals.com

April, 2013

It looks nice and hefty sitting next to a Canon 135mm f/2.

It looks much better mounted to a Canon 5D Mk III in my hands, don’t you think?

Imatest Results

We tested on the Canon 5D Mk II so we could directly compare it to one of my favorite lenses, the Canon 135mm f/2.0. The Canon is one of the sharpest lenses at f/2.0 we’ve tested. Below are the Imatest MTF50 results at the center, averaged at 13 points over the front surface of the lens, and the average of the 4 corners.

Long live the new King! The new Zeiss 135mm T2.1 CP.2 (and the hopefully soon to be available ZE and ZF f/2.0) have some pretty amazing numbers. Particularly in the corners. We’ve never had anything do better at this aperture.

I don’t have any nice pictures for you, but there are several people who have gotten copies already and have posted some impressive images. Here are a few links but there are lots more:

http://zeissimages.com/showreplies.php?qid=950

http://www.dpreview.com/forums/post/51185931

http://zeissimages.com/standardgallery.php?lenstype=557&showall

Pretty impressive stuff. It’s priced at $2,200. That’s going to make for a tough decision for Canon shooters with the excellent Canon 135mm f/2.0 lens available at less than half that price. I don’t think anyone will ever complain about the Zeiss image quality, though. It’s spectacular.

Roger Cicala
Lensrentals.com
April, 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

Comparing the Specs

The Zeiss is a bit pricier than the others lenses in this range, and a bit larger. But you get twice as many aperture blades for your money. Not to mention it has significantly more light transmission. Don’t you wish photo lens makers had to use actual transmission (T) instead of theoretical calculations (f)? Looking at the table you kind of see why the camera makers might rather not.

	Zeiss CP.2	Canon IS II	Nikon VR II	Tamron VC	Sigma OS
Price	$19,900.00	$2,200.00	$2,400.00	$1,499.00	$1,249.00
Weight (lb)	6.2	3.3	3.4	3.2	3.15
Length (in)	9.85	7.8	8.1	7.4	7.8
Aperture blades	18	8	9	9	9
Min. Foc Dist. (ft.)	5	3.9	4.6	4.2	4.6
T#	2.9	3.4	3.3	3.2	3.2

Ok, enough of the silliness. The Zeiss lens is clearly an entirely different beast and while we can mount it to our SLRs that’s not what it’s designed for. That extra money and weight go into making it a true cinema lens with long, smooth focus and zoom gearing. It’s also really parfocal, meaning if you focus on something at 70mm and zoom out to 200mm the object is still in focus. None of the photo lenses are (although budget minded cinematographers desperately want them to be).

Just a Little Bit of Handling

I could go on for some time about how accurately it focuses (it does), how smoothly it zooms (totally true) or how it’s not too heavy to hand hold for a while (a complete lie – it weighs almost as much as a Canon 500 f/4 IS II). This is a lens designed from the ground up to be mounted to a set of rails and focused with a geared follow focus system. It’s perfect for that and built as solidly as any cinema lens we carry.

Cinema lenses, as a rule, are designed differently than photo lenses. Photo lenses are about rapid autofocus, which means rear or inner focusing. That in turn means focus breathing, often to the point of massive changes in focal length when you focus closely. Being parfocal is of little importance for a rapidly autofocusing photo lens. When you zoom from 80 to 150mm if the camera can autofocus in a split second, who cares if it’s still in focus after the move? Not to mention the subject might be moving anyway. Being parfocal is very important for a cinema zoom.

We did a quick parfocal check, comparing it with the Canon 70-200 f/2.8 IS II, which is not parfocal (but actually sort of close to it). We simply set the lenses at 70mm and live view focused on the bush in the center with each lens.

Then zoomed to 200mm and took another image.

Here are 100% crops of the bush at 200mm with the Zeiss on the left, Canon on the right.

We did a quick check for focus breathing, too. I won’t repeat the Canon lens, it breathes significantly and the focal length changes as you zoom close. The Zeiss 70-200 did not focus breath significantly from far to near focusing.

Yes, I Had to Run the Numbers

Absolute resolution, historically, has been far more important for a photo lens sitting in front of a high-resolution sensor than a video lens. Even 4K video is about 8 megapixels, not nearly as resolution sensitive as a 36 megapixel SLR. So when we’ve tested video lenses for resolution compared to photo lenses they’ve historically not held up well. Resolution isn’t their primary focus.

But we thought we’d see if the Zeiss could hold its own against the best 70-200 f2.8 photo zoom we have, the Canon 70-200 f/2.8 IS II. Because the Canon is actually shooting at T3.4, we tested the Zeiss wide open (T2.9) and also stopped down slightly to T4. I’m not going to clutter up the tables with the T4 numbers – this lens is as sharp wide open as it is stopped down, with the exception that the corners get just a tiny bit better at T4.

These are Imatest MTF50 results using a Canon 5D II test camera showing point sharpness at the center, average over the entire lens, and average of the 4 corners.

	Center MTF50	Avg. MTF50	Avg. Corner MTF50
Zeiss@ 70mm	990	775	600
Zeiss@ 135mm	915	675	575
Zeiss@ 200mm	815	575	425
Canon@ 70mm	875	755	575
Canon @ 200mm	840	720	525

Well, as you can see from the table, the Zeiss 70-200 T2.9 takes the idea of video lenses being lower resolution and shows that at the right price point, you really do get it all. At 70mm it’s clearly outresolving the Canon 70-200 f/2.8 IS II. The MTF50 decreases steadily at longer zoom lengths, but even at 200mm it’s still as sharp in the center as the Canon, which is the highest resolving 70-200 zoom we’ve tested. And remember the Canon is working at T3.4 wide open, a half stop slower than the Zeiss.

Let’s keep some perspective – if I were a photographer I wouldn’t be spending this kind of money for a 6-pound 70-200mm zoom because it’s sharper at the wide end. And even shooting 6k video I suspect you’d be hard pressed to detect a huge difference in your footage at 70mm. But now you can have a true cinema lens with long focus and zoom throws, properly geared for follow (and zoom) focus, parfocal and without significant breathing that’s as sharp as any photo lens made.

While $20,000 is sticker shock for my photography colleagues, consider a set of three Cooke Panchro primes covering the same focal length at the same aperture costs $22,000 and doesn’t even approach the Zeiss in resolution. Plus Zeiss lenses don’t tend to spit out focus helicoid collars and require a $600 repair every 3 months like Panchros do.

Roger Cicala and Aaron Closz

Lensrentals.com

April, 2012

BTW – I know what you’re thinking. Yes, I do love my job.

Does it improve my composition and technique? No. But knowing this stuff can be helpful. For example, when I want to shoot a landscape at 70mm and f/5.6 will my corners be sharper with my 24-70 f/2.8 or a 70-200 f/2.8? Or which will have less distortion for an architectural shot (since I hate the resolution loss of correcting distortion in post), my 35mm f/1.4 or my 24-70 zoom at 35mm? (Surprisingly, the answer is my zoom.)

This kind of information is easy to find. DxoMark has nice graphs for each lens that show distortion, vignetting, chromatic aberration, and resolution at various focal lengths and apertures for each lens they test. SLRgear.com has a nice pop-up app that shows the resolution across the field of the lens at various apertures and focal lengths.  The Digital Picture has great pop-ups that let you compare two lenses side-by-side for flare, distortion, vignetting and even images of ISO 12233 crops.

A lot of people use those tools when deciding which lens to buy. I use them after I have the lens so I know how to best use it.

 Resolution Maps

One thing that I’ve started using more frequently in post processing is a resolution map of the lens. We all know that every lens has highest resolution in the center and less in the corners. But the pattern of sharpness is different for different lenses.

Some lenses have a high peak of resolution right in the center that quickly drops off. Others maintain significantly high resolution halfway to the corners and then drop like a rock. Others have a rather linear drop-off from the center to the corners.

Just as an example, below are 6 Imatest charts showing MTF50 of 6 different lenses across the field of view. The absolute resolution numbers aren’t important for this demonstration, rather it’s the pattern of how the resolution changes. For each lens, yellow is the highest MTF50, blue is about 1/3 the value of yellow.

Why Does it Matter?

There are a lot of reasons, of course. But one I use a lot is creating sharpening maks for postprocessing. Like a lot of people, I use a masked layer for sharpening, applying less sharpening to the already sharp center of the image, and more sharpening to the softer areas. Instead of just a generic oval, I try to make a mask that mirrors the resolution map of the lens I’m shooting with.

I keep masks as actions for my most commonly used lenses, which speeds up postprocessing considerably. For example, I’d use something like the first mask, below, for images shot with the lens on the upper left above, and the second mask for middle right lens above.

As an example I’ll use two 100% crops from the left edge of this snapshot.

The crop on the left shows what that edge looks like when I sharpened the entire image to give best center sharpness. The crop on the right was when I used a mask to use stronger sharpening, but only at 50% strength in the center of the image. With either technique the center looked the same, but the edges were quite different.

Of course you can simply use an oval mask and adjust it for each image with a bit of trial and error. But I had 500 vacation photos to go through. Since 75% of them were taken with one lens at the same aperture, saving an action with the appropriate sharpening made that quick and easy.

You don’t need Imatest to figure out the sharpness pattern for the lenses you have. A simple photograph of a flat wall or fence with reasonable detail (bricks or unpainted wood are nice) will let you see where each lens starts to soften and by how much. Once you’ve made a good mask for that lens you have it forever. For most lenses, the same mask can be used at different apertures – you simply reduce the strength of the layer if you’ve shot stopped down. For other lenses, though, like my Zeiss 50mm f/1.4, you will need to make masks for different apertures.

Uwe Steinmueller at OutbackPhoto.net and I have been doing a series of articles trying to show how a little gear head knowledge and a little post-processing knowledge compliment each other and help make better images, and this is a great opportunity for that. Uwe’s article and action for corner sharpening, provide a nice photographic demonstration of how sharpening with a mask improves your end result, and a nice script with an adjustable mask.

Roger Cicala

Lensrentals.com

April, 2012