Anyway, it’s the new version of the Sigma 120-300mm f/2.8 OS lens. Optically it’s unchanged from previous versions. That’s fine; it’s always been an excellent lens optically. One very apparent change is it’s compatible with Sigma’s USB dock that allows you to fine tune autofocus, focus speed, and the OS system. That’s a good thing.

The 120-300mm f/2.8 OS has pretty much summed up my long-term love-hate relationship with Sigma. How could I not love an f/2.8 zoom in this range with great optics? How could I not hate that for 2 years it’s been our most frequently repaired lens, lasting an average of 13 weeks before going back to the factory?

But there’s no question Sigma is different now. The repair service has greatly improved. Sending a 120-300mm f/2.8 in for repair a couple of years ago might mean it was gone for months. Now they’re back in a couple of weeks, and fixed at a reasonable price. They’re releasing world-class lenses right and left. They’ve given us unprecedented control with the USB dock. And they state they’ve improved quality control.

But I have to admit after my frustrations with Sigma 120-300s and 50-500s over the last several years, I have to admit I feel like Charlie Brown listening to Lucy promise to not pull the football back this time.

My usual disclaimer applies: I’m not a lens reviewer and this isn’t a lens review. This lens is frequently used for rapid-fire action shooting requiring critically accurate autofocus, so thorough assessment will require in-depth evaluation by someone far more skilled in that type of shooting than I am. But I can contribute some evaluation of features, stationary optics and construction quality.

The USB Dock and Sigma Optimization Pro Software

After using the USB dock and software to set up a few copies, I was impressed. When you plug the lens in the dock and open the software you get a nice splash page that will update firmware if needed, or let you choose to fine tune autofocus or adjust customizable options.

 The Customization page lets you adjust focus limiter settings, OS settings and AF Speed. 

AF Speed adjustment is straightforward: you can choose standard, speed-priority, or accuracy priority.  We did the simple thing and timed the lens from minimum focus to infinity focus. Standard speed took 0.95 seconds, while speed priority dropped this to 0.7 seconds and accuracy priority increased it to 1.1 seconds. Measuring change in accuracy will require someone with more capabilities than I have, but the nice thing is you get two custom options on the lens so you could set C1 to speed priority and C2 to accuracy priority and switch on the fly if needed.

The focus limiter adjustment is nicely done with a simple slider you can adjust in case the default 10 meter to infinity limiter isn’t ideal for you.

The OS customization page left me confused. You can read it and explain it to me if you understand it. I will say I tried all three settings and you can tell a difference in the viewfinder as far as the image appearing more ‘locked in’ with Dynamic mode. Taking pictures, though, I didn’t see any obvious difference in the amount of stabilization I was getting, but this was very limited testing, shooting still targets handheld after a fairly massive coffee intake.

To me, the most important part of the Optimization is the ability to fine tune autofocus. For those of you willing to take a little time fine-tuning your lens, this part is simply amazing. You get the ability to adjust autofocus at 4 different focal lengths, each of which can be adjusted at 4 different focusing distances.

Now I totally realize that half of you are so excited about this you can hardly stand it, half of you think this is way too much work, and the other half have mixed emotions about it. Here’s my take having walked about 500 people through using this lens. Occasionally the 120-300 clearly back or front focuses everywhere. If that’s the case, microfocus adjustment on your camera will work just fine.

More commonly, people notice a problem at one end of the zoom range and/or one extreme of focusing distance. It really shouldn’t take you more than half an hour to go shoot some appropriate test shots and see if your lens has such an issue. If it does, fix what needs fixing and leave the rest alone. From long experience with multiple copies of this lens, I expect most people will have a final window with 3 or 4 boxes in one corner requiring some adjustment and the rest zeros.

One thing I will add that I’ve only recently learned from Rich Meston at Focal: The Sigma 120-300 has significant focus shift, so those of you who want to shoot it at f/4 or f/5.6 may need to make more significant adjustments to compensate for that. However, make sure you want to shoot at that aperture all of the time, since such adjustments will probably throw off your autofocus wide open.

I truly believe the past problems with front and back focus at various focal lengths on different cameras can now be fixed by anyone who’s willing to spend a little time setting up. I love the “C” button that lets me use the dock to customize AF speed and OS. I can’t say how the autofocus and OS system customization will work out, but it is nice to have those kinds of options. Certainly a lot of people will benefit from being able to set the focus limiter system to whatever distance they like.

Optical Testing

Until recently our Imatest lab wasn’t set up to handle a lens of this size so I never optically tested the original version of the 120-300mm f/2.8 OS. Since I’d recently tested some of the new Canon Supertelephoto lenses, though, it seemed reasonable to see how the Sigma compared with them. (Just in case you didn’t know, there is no need to do optical comparison tests between the old and new versions of the 120-300 f/2.8 OS because they are optically identical.)

Just for convenience, I’ve created a table of the various options to the Sigma in Canon mount since that’s what I’ve been testing recently.

Lens	Weight (lb.)	Price
Sigma 120-300 F/2.8 OS	6.7	$3,600
Canon 300mm f2.8 IS II	5.2	$6,800
Canon 200-400 f/4 IS	8	$11,800

No question why the Sigma is an attractive option to the Canon 300 f/2.8 IS II when you look at prices and consider that it zooms. With a 1.4x teleconverter it also makes an attractive alternative to Canon’s 200-400 f/4 lens. Now let’s see how it compares with those other lenses optically.

As usual, tests were done in our Imatest lab at distances of 25 to 35 feet — results may have been slightly different at infinity. The table below shows the Sigma 120-300 f/2.8 at 300mm. Because it isn’t really fair to compare a zoom lens to a prime, I also added the results of the Canon 70-200 f/2.8 IS II lens tested at 200mm to give a comparison to another zoom.

Lens	MTF50 Center	MTF50 Average	MTF50 avg. corner
Sigma 120-300 f/2.8	820	690	675
Canon 300 f/2.8 IS II	910	825	720
Canon 70-200 f/2.8 IS II	895	745	680

The results aren’t too surprising: the Sigma is not as sharp as a $6,000 prime lens, but it’s still very good. It’s very close to one of the sharpest zooms made, the Canon 70-200 f/2.8 IS II. Could you see the difference between the three lenses? Yes, you should be able to if the images were side by side in a reasonably large print.

But I sure can’t tell you if the difference between the Sigma and Canon is worth the money to you, nor can I say whether the Canon’s lighter weight or the Sigma’s zoom capabilities are going to be important to you. Certainly the Sigma will be plenty sharp for most people.

The other comparison I’ve been asked to make several times was to compare the Sigma with 1.4x teleconverter to the Canon 200-400. I had planned to test with both the Sigma and Canon 1.4x converters, but we were completely out of stock of the Sigma, so for this test the Sigma is mounted to a Canon 1.4x TC III. The Sigma might have done better (or worse) with a Sigma teleconverter. To give a reference point, I’ve included the Canon 100-400 IS L zoom at 400mm, too.

Lens	MTF50 Center	MTF50 average	MTF50 avg corner
Sigma 420 f/4	775	660	600
Canon 200-400 f/4	910	820	720
Canon 100-400 f/5.6	740	655	540

Adding a teleconverter reduces resolution as always, although not quite as much as I had expected, honestly. Even with the converter in place, the Sigma does a bit better than the Canon 100-400, which is a very good performance indeed. The 200-400 is much better, but at that price it should be. The bottom line is I think most people would be very happy with the Sigma’s resolution, even with a 1.4x teleconverter.

Conclusion:

There’s nothing shocking here. The Sigma 120-300 f/2.8 is a very sharp lens. It’s not as sharp as lenses costing far more, but it’s certainly  very good.

The USB dock / Optimization Pro software is really cool. My playing with it in the lab is not the same as people using it for weeks in the field, so I don’t want to make unjustified conclusions, but it seems likely to make the lens more usable than the original version was.

Would I pay the difference to get the new Sigma when the old version is $1,000 cheaper? Absolutely not if I already had a copy I was happy with. The optics are identical and if you’re happy with your version you probably don’t need the features of the dock and software.

If I was trying the lens again after being unhappy with a previous copy, or buying for the first time . . . . well, to me it would really come down to whether the new version is also more reliable. I like the programmability, I really do. But this is a steep upgrade price for that alone. On the other hand, if build quality and reliability is better, then yes, I’d pay the difference.

So, guess what? (Yeah, you knew this was coming.) In Part II we’ll do a side-by-side teardown of an old and new version of the 120-300 and see what differences we find.

Roger Cicala and Aaron Closz

Lensrentals.com

June, 2013

Anyway, given that a lens with electronic autofocus and aperture control was something new in the Zeiss consumer lineup, Aaron and I couldn’t wait to take a look inside and see how things were put together. Once we got a look inside, we found there was more Touit than we expected (don’t say I didn’t warn you). The lens is put together solidly in typical Zeiss fashion.

Outside examination of the 32mm Touit shows us the polymer barrel with metal mounting ring. Things appear solidly built and the focus ring, particularly, moves smoothly like a larger SLR lens (many mirrorless focus rings are loose and sloppy).

The rear light baffle is a separate piece mounted by three screws.

The rear mount then removes in the usual way.  Underneath the rear mount is a thick metal shim or spacer.

It seems rather thick to be a standard optical shim or adjustment for the difference in Fuji and Sony flange-to-sensor distances (which are only 0.3mm different), so I assume it is there for added structural rigidity.

With the spacer removed we can see the rear barrel of the lens is attached by 3 large screws and an additional two screws hold the rear PCB (circuit board) in place. This is typical sturdy Zeiss construction; the screws are longer and thicker than what you usually see in lenses of this size. At 10 o’clock you can see the silver cylinder of the DC motor peeking out from under the PCB, with the large flex connector from the PCB board heading to it.

Removing the rear barrel exposes the inner barrel and PCB board. The white ring you see on around the barrel serves as a bearing to make rotation of the focus ring on the rear barrel smooth. Again, one of those ‘well-built’ touches. It’s that smoother, tighter fit that keeps the focus ring from feeling loose and sloppy.

In a closer view you can see the notches along the focusing barrel and the optical position sensor it uses. (NOTE: after I published this a person more knowledgeable than myself corrected me – this is a hall sensor, not an optical sensor, but the purpose is to sense the movement of the manual focusing ring.)

After the PCB is removed the position sensor can also be removed.

Which lets us remove the DC motor. I will admit, when Zeiss stated they went with a DC motor because they wanted a more powerful motor to move the focusing quickly, I was skeptical (and still am, a bit) but this is quite a large motor for such a small lens. If I read Zeiss’ technical description properly, focusing involves moving the entire optical assembly in one direction and possibly the rear floating element a different amount, so a large motor probably is required.

At this point it’s time to turn the lens over and start working our way in from the front. The makeup ring is removed (the liquid you see is some alcohol used to soften the glue) which exposes the screws holding the front barrel in place. Again, oversize screws with coarse threads that felt very secure.

The filter ring barrel comes off after removing those three screws, and that lets us also take up the focusing ring.

These next three screws let us remove the front mounting plate. Notice how they’ve designed these thick mounting plates front and rear that accept all the attachements of the outside barrels (and therefore accept the direct stress when you drop the lens, etc.)

After we’ve removed this plate, the actual optics of the lens come out as a unit. So all of this dissection, layers of barrels, multiple screws, etc. are simply to handle the housing. The optics now come out in an entirely separate unit. This is quality construction.

The halves of this inner housing are held together with another nice touch. Three sturdy post screws, but each screw has an associated spring and washer. If I’m understanding their purpose correctly, it should maintain even  tension, broaden the area where pressure is applied and help avoid overtightening. Like several other things we’ve seen in this lens, they could have saved a few bucks by using a simple screw and few people would ever know. I point these things out because sometimes the insides of higher-priced lenses do show us a bit about why they’re higher priced lenses.

With the innermost barrels separated you can see the aperture electronics at the bottom of the lens in the picture below. There also appears to be a second, magnetic, position sensing strip that Aaron is pointing to with the screwdriver . . .

Matched to a second position sensor (again, Aaron’s screwdriver pointing to it).

I’m guessing the outer system is to sense turning of the manual focus ring for the fly-by-wire focusing system, and this one is the actual autofocus position sensor, but I could have that backwards, or just be totally wrong. With my luck this is some kind of secret-monolith tampering sensor that sent a signal to Germany the minute it was exposed to light, making sure they don’t invite me to any more lens releases.

Credit: 2001, A Space Odyssey.

We did not open up the optical elements for a couple of reasons. First among theses was the fact that we were much more interested in the electronics and focusing system. After all this is Zeiss’ first autofocus (and for NEX electronic aperture) lens. I don’t have any questions Zeiss makes great optics but I was interested in seeing what their electronics looks like.

Second was the very thorough construction made it take a significant amount of time to get to this point and we have to put this back together and get to our daily repair work. Third, the 32mm Touit, like many wide-aperture lenses in this focal length, is based on a classic double-guass design with only 5 groups. There is rarely much to see or adjust within the optics of theses type of lenses and most of the elements will be cemented or solidly encased in groups.

Optical diagram of the 32mm Touit

In fact, the 32mm Touit is really just an optically improved version of the ZM 50mm Planar (there are some changes in the 6 elements that make up the double-gauss design and the addition of a rear group, probably for aberration compensation and perhaps as a field flattener and / or floating element.

Optical diagram of Zeiss ZM 50mm Planar

Conclusions:

This thing is built well. Those of you who have misgivings about polymer (rather than metal) construction in a lens of this size, put those to rest. It’s built like a Zeiss; I expected no less. I was a bit skeptical about the choice of a DC motor to provide more power, but I have to say, they definitely chose a large, powerful motor, so that was probably just me being cynical.

The overall construction and design were very solid, reminding me of a Zeiss or Leica rangefinder lens; much higher construction quality than many of the E mount lenses I’ve opened up.

I should point out that I have not yet opened up a Fuji-mount Touit. It will be interesting to see the differences between the two (aperture control being the most obvious). I also don’t want my remark about E mount lenses above to be carried over to Fuji. I have less experience looking inside Fuji lenses, and to be honest find them a bit strange, but they are well constructed.

All photos copyright Roger Cicala and Lensrentals.com, 2013 unless otherwise noted. (You may reproduce them as long as the copyright credit is given AND links back to this article.)

Roger Cicala and Aaron Cosz

Lensrentals.com

June, 2013

I think it important that anyone who writes an opinion on any item should be very clear in stating what, if any, benefits they received that might influence them concerning that item. (You hardly ever see me mention any, because I hardly ever get any). In this case, however, Zeiss USA loaned me E-mount 12mm and 32mm Touit lenses for two weeks to test and review. They also invited me to the press release of the Touit lenses in New York and payed for one night’s hotel room there. 

A few years ago I was accused of being a Sigma hater. (For the record, I did hate their quality control and so-called repair service at that time, and I didn’t hesitate to say so in this blog.) For the third or fourth time in the last year, I’m about to be accused of being a Sigma fanboy.

I’m pretty certain I haven’t gone soft over the last 4 years. I am certain, though, that Sigma Photo, Inc. has changed a lot in that time. Truth is, they’re making serious waves in the photo industry these last few years. They’ve improved their repair service and quality assurance. They’ve released some world-class lenses at way less than world-class prices lately. And now they’ve released their USB dock and Optimization Pro software.

I’ve spent the weekend playing with it. Partly because I really think this is a revolutionary product and I wanted to see how it worked. Partly because I desperately need a ‘Honey, I’ve really got to do this for work’ excuse or I’d have been restaining the deck.

My conclusion, as usual, first: if anything is going to get the attention of those who like to disable features in firmware, overprice lenses, and limit our ability to customize, this might be it. I did some adjustments this weekend, in about 10 minutes, which would have required a trip to factory service on a Canon or Nikon lens. And let me stop the Fanboy stuff before it starts: you may never have needed to make this adjustment on your 10 or 20 Canon or Nikon lenses, but I’ve sent dozens of them to factory service adjustments for exactly the issue I’m going to demonstrate today.

Quick Overview of the USB Dock and Optimization Pro software

The directions are pretty simple:

• Make sure you buy the dock in the proper mount (Canon, Nikon, or Sigma).
• Download the Optimization Pro Software HERE. It’s about 3.4 Mb in a zip file, available for Windows or Mac.
• Open the software, put the lens in the USB dock, and plug the USB port in your computer.

Once you hook things up the program the program opens to a nice, straightforward main page.

The firmware update button reads the lens’ firmware and lets you know if you need a firmware update. Push yes and it updates in about 20 seconds.

Adjusting a Lens

First of all, there’s a nice 10-minute video that Sigma made that shows you the use of the device very clearly HERE. If you’re like me, though, you might prefer a 30 second blog read. It really is that simple. Actually, 10 minutes is more time than it took me to do my first adjustment on the 35mm f/1.4 (of course, without reading any manuals).

I should be clear, I don’t do a full-ballistic, OCD, 600-shot microfocus adjustment. I’m too aware that phase detection AF is a shotgun, not a sniper’s rifle. I’ll take nearly perfect in 10 minutes rather than perfect in 4 hours every time. Plus, like I said, I’ve got a deck to stain. Unless I can put it off so long that my wife gets frustrated and does it herself.

I chose a lens that is perfect for this software. This copy of the 35mm f/1.4 is perfect on my Canon 6D at close and intermediate distances, but at long distances it backfocuses badly. I can do a microfocus adjustment to correct long-distance focus, but then the lens is frontfocusing at near distances. Without the Sigma dock and software, the only option was a trip to the factory service center to change the lens parameters.

Since I was at home instead of the office, I didn’t have Focal, LensAlign charts, or any of the other things that seem to be considered necessary tools for autofocus adjustment these days. So I made do with a placemat and my back yard.

Since I plan on using this lens outdoors in daylight I wanted to adjust it in daylight (autofocus can change slightly in different lighting conditions, if you aren’t aware). I started with a placemat set in front of a picture window.

Spot focusing on the tip of the green leaf, I took several shots each at minimum focusing distance, 3 feet, and 6 feet. They all showed focus was accurate, as in the samples below.

Focusing at longer distances, however, showed the lens backfocused quite dramatically. In this image the focus point was on the small yellow leaf in the foreground (I’ve cropped the image to show the area behind the focus point).

Opening up the Sigma adjustment window shows I can make adjustments at 4 distances. With the 35mm, 3 of those are close: roughly 0.3, 0.4 and 0.7 meters. The other is infinity.

I left the close adjustments at zero and gave infinity adjustment a -12. You just click on the area you want to adjust, move the slider the amount you want adjusted, and then click the “Rewriting” button. (The “Rewriting” button is the only part of the software that isn’t totally intuitive; it isn’t highlighted until after you click on it.)

A repeat shot outside showed -12 was way too much adjustment so I went back and reset the infinity adjustment to -8. That was spot on as shown in the image below. I rechecked AF at closer distances and it had not changed a bit.

Total elapsed time for firmware update, focus checks, focus adjustments, and final check was just about 10 minutes. Obviously a zoom lens, which can be adjusted both at different focal lengths for different focusing distances at each focal length, will take longer.

Conclusion

For the even slightly gear-head amongst us, this is an awesome tool, giving us the ability to fine-tune autofocus adjustment much more completely than simple camera microfocus adjustment. At $59, I consider it an amazing bargain for anyone who owns one of the Sigma Art, Contemporary, or Sports lenses (it does not work on older lenses).

I’ve already heard a couple of people complain that it should be included with the lenses but I disagree. First, the price is very reasonable and the software is free. Why would they include it with each lens (which probably means each lens costs $59 more) when you only need one for all of your lenses? Not to mention half the people who got it would never use it.

I’ve heard others state that only Sigma lenses need such a device. I’ll meet them part way: I think there is probably a more frequent need for such adjustment on third-party lenses, but I can absolutely guarantee you that the big-boy’s lenses do indeed have this same kind of problem, at least occasionally.

Whether they need it more frequently or not, now Sigma DOES have such a device. Which means, for example (just pulling a random lens out of my hat), the Sigma 35mm f/1.4 is now not only sharper and less expensive, but also more accurately adjustable than the manufacturer’s 35mm f/1.4. I wonder if anyone is hearing footsteps*?

Roger Cicala

Lensrentals.com

June, 2013

* For my non U. S. readers, hearing footsteps is a term used to describe an American football player, who, thinking he is wide open and about to catch a pass, unexpectedly hears the footsteps of an unseen opposing player about to crush him.

I sure can’t tell you if a lens is worth $12,000 by running a few Imatest numbers, but I might be able to tell you if it sucked. So when we got our first 200-400 f/4 IS lenses in, they went straight back to the lab, along with some other lenses for comparison purposes.

First, I need to be clear we have some limitations in our Imatest lab. Because of space and target size we’re limited right now to a maximum testing focal length of 400mm, so I can’t do a 560mm test with the teleconverter in place. But we had some reasonable options for testing at 400mm: the 400mm f/2.8 II, which is probably the sharpest telephoto lens made right now; the Canon 100-400mm, an older but classic design; and the 400mm f/5.6L prime lens, another oldie-but-goodie lens. My thinking was at this price the 200-400 should be nearly as good as the 400mm f/2.8 and clearly better than the other two lenses.

The test lenses from left to right: Canon 200-400mm IS L, Canon 400mm f/5.6 L, Canon 400mm f/2.8 IS II, and Canon 100-400 IS L. In back, the Imatest target they'll be compared on.

Or to give you a better perspective, here’s the entire current Canon Supertelephoto lineup (reproduced with permission from TheDigitalPicture.com). The 200-400 is the 4th from the left, with the 400 f/2.8 II on it’s left and the 500 f/4 on the right.

copyright Bryan Carnathan, the Digital Picture

Tale of the Tape

The Canon 100-400 and 400 f/5.6 lenses are both considered ‘hand holdable’, weighing 3 pounds and 2.7 pounds, respectively. The 400mm f/2.8 IS II at 8.5 pounds is not, except for purposes of showing off. I’d have to say the 200-400 is not, either, at just under 8 pounds. Canon doesn’t quite charge by the pound, with the 200-400 the most expensive at $11,800, the 400 f/2.8 II at $10,999, the 100-400 IS L $1,500, and the 400 f/5.6 $1,219. For those of you hang out in supermarkets, that puts the 200-400 at $1,475 per pound, while the 400 f/5.6 is only $451 per pound.

I shot around with all of them and thought that, perhaps, the 100-400 was just a bit slower to autofocus than the others, but it wasn’t a dramatic difference. Since I shoot the 100-400 frequently and find its AF speed quite acceptable, they certainly all pass in my book. Shooting handheld around the office, there is no question the IS on the 2 big lenses was far better than that on the 100-400. Despite their weight I actually got sharper pictures at 1/30 or so with the big lenses.

Imatest Results

I’ll cut to the chase and post the MTF50 results from all of the  lenses in table form. Because of time constraints (all of the first copies of the 200-400 we received today had customers waiting for them, so they had to be in the shipping department by lunchtime) I could only test at one focal length – setting up Imatest for telephoto work is quite time consuming. Results are, as usual, MTF 50 measured in line pairs / image height on 5D Mk II test cameras. They are given as center point, weighted average over the entire lens, and average of the 4 corners.

The numbers for the 200-400 are basically as good as anyone could possibly hope. At f/4 it is virtually indistinguishable from the 400mm f/2.8 at f/2.8. That’s an amazing thing for a zoom lens to do. To look at it another way, the highest MTF 50 numbers we’ve had for a zoom on 5DII cameras is the 70-200 f/2.8 IS II which has peak MTF50 of 875 LP/IH and average of 755.

As I mentioned, I wasn’t able to test the built-in 1.4X teleconverter at maximum range, but we could dial the zoom back to 290mm, add in the 1.4X, and repeat our tests at our 400mm testing setup. The resolution numbers for the 200-400 and 1.4X combination at 400mm equivalence were 835 LP/IH in the center, 750 average, and 660 in the corners.

Of course resolution decreases with a teleconverter, it always does. But even with the teleconverter active the 200-400 still resolves about as well as a 70-200 f/2.8 lens, which is really excellent. I also suspect that if we had the ability to test at infinity the numbers would be even better; teleconverters are designed to work at longer distances, not the 35 feet of our test range.

Now, for one little bit of rain on our parade. The 200-400 isn’t quite 400mm at the long end. We measured the focal length of the 400 f/2.8 II and 400 f/5.6 as identical, while the 200-400 reached 95% of that focal length. (Assuming the other two are exactly 400mm, the 200-400 therefore reaches 380mm. For those interested, the 100-400 would be a 390mm.) Again, this is measured at 35 feet, it might be slightly different at infinity.

I can’t say whether it’s worth the price or not, but I can certainly say it’s the sharpest zoom lens I’ve ever seen (correction – as Rick pointed out, the 200-400 is roughly tied for highest resolving zoom with the Canon 24-70), with image quality rivaling the most expensive primes.

Roger Cicala

Lensrentals.com

June, 2013

This is more speculative than what I usually write. Generally I wait until we have multiple copies to run Imatest, look at sample variation, etc. In this case, though, it became apparent that when we do get full stock in, it’s all going to go right back out on rental since there’s already a waiting list. So I thought it would be worth investigating the single Zeiss 32mm f/1.8 copy we had.

Background

I don’t want to repeat what everyone already knows, but there are a couple of points I think need emphasis:

1) The Touit lenses are going to be slightly different in Sony and Fuji mounts. The Sony’s have electronic apertures, the Fuji’s mechanical. The optics may vary a bit, too. Differences in flange-to-sensor distance and Fuji’s raw manipulation account for that. I mention it because you should look at reviews of the lens in the mount you are interested in. This is about the Sony E mount because, well, that’s what they loaned me.

2) These are autofocus lenses. The AF system has a DC motor, not an ultrasonic motor. It works well, but it makes a bit of noise which would probably make it a poor choice for video. It’s not a horrid noise by any means, lower pitched and much less buzzy than DC motors in other lenses I’ve used, but it’s noticeable when things are quiet.

3) The manual focus ring is fly-by-wire. Turning the MF ring actuates the DC motor, not a mechanical linkage. It’s one of the better implementations I’ve seen and I had no trouble focusing accurately (much better than, say, the Canon 85mm f/1.2). But again, video people pulling focus will have the electric motor making noise in the background.

4) These two lenses will be followed by a 50mm macro lens in the fall. There will be some other lenses in 2014 and at least consideration is being given to a zoom lens.

5) There are no immediate plans for Micro 4/3 mount Touit lenses.

A Few Subjective Observations

First, I always try to say what my point of view is when I start a post, because I know it influences my opinions to some degree. I’ve made no secret I consider the NEX system to be one of great cameras with generally poor lenses.

Before shooting with them I was much more excited about the 12mm Touit than the 32mm simply because there was not a good wide-angle prime at any price for the NEX. After shooting with them I found the 12mm had fairly blurry corners wide open on the NEX-7. It may be better on the NEX-6 but I didn’t shoot it on that camera.

For this test I looked at the Touit 32mm f/1.8, partly because I liked it better, partly because the Sony 35mm f/1.8 OSS provides a good comparison point. I consider the Sony 35mm to be a good, but not great lens (although it’s one of the better NEX lenses). It’s reasonably sharp wide open, becoming quite sharp around f/2.8. I like the OSS and price is excellent.

The Sigma 30mm f/2.8 E-mount lens provides a third option in this approximate focal length. It doesn’t have as wide an aperture, but it is does have an amazingly low price tag.

Just shooting around with the 32mm Touit I was impressed, particularly by center sharpness and particularly stopped down just a bit. I also loved the close focusing distance (1.2 feet minimum) that let’s it almost be used as a pseudomacro with a 1:9 maximum magnification. Wide open, I wasn’t blown away by it, but stopped down it was awesome.

Imatest Results

I want to point out that these results are from a single copy of the 32mm f/1.8 Touit, not my usual multiple copies, because we don’t have stock yet, just the one loaner copy Zeiss was kind enough to provide us.  I see nothing that makes me think this copy is out of sorts, but until we test multiple copies we don’t know that this one is representative.

I compared it to a group of 5 copies of the Sony 35mm f/1.8 OSS lens (since we hadn’t tested that one before I thought it best to go ahead and get reliable results now). The Sony 35 had an interesting sample variation: all copies had a slightly soft corner. Just one corner. Not the same corner. But always one. It wasn’t awful by any means, but MTF values in 1 corner were always 20% lower than the other 3 corners.

We’ll start with the MTF50 graphs for the Sony 35mm f/2.8 OSS, which as I mentioned, is a pretty good lens.

The Sony starts out pretty well for a wide aperture lens, with center resolution of 790 Line Pairs / Image Height in the center and 595 average at f/1.8 on the NEX-7. At f/2.8 the lens sharpens dramatically with MTF50 of 1030 in the center and 805 average. This is slightly better than the Sigma 30mm f/2.8 which has an MTF50 of 985 center and 805 average at f/2.8, increasing to 1040 / 840 at f/4.

Imatest results for the Zeiss Touit 32mm were even better.

At f/1.8 the results were similar to the Sony 35mm, with MTF50 of 800 in the center and 630 average. The Touit sharpens up more quickly, though, having MTF50 results at f/2.2 (1190 center, 830 average) that are much better than the Sony. AT f/2.8 through f/5.6 the Touit has significantly higher MTF50 than the Sony. I had mentioned online that wide open I thought the Sony and Touit were fairly similar, but that stopped down just a bit the Touit was clearly resolving more. These numbers support that.

I should mention also that the Sony lens, even on the NEX-7 does not reach maximum resolution until f/5.6, while the Touit maxes out at f/4. The Sony exhibited less distortion, with 0.5% barrel distortion compared to 2.1% for the Touit in our tests.

It has been stated the 32mm also has a lot of field curvature, but we didn’t see this in our testing. Corner sharpness was not improved greatly by corner specific focusing. Our tests were done at about 13 feet shooting distance. Things may be different at other shooting distances.

Conclusion

This is a great example, I think, of why test numbers are just one thing to consider in choosing a lens. According to the test results, if you want the best bargain and shoot at f/2.8 or smaller, the Sigma 30mm f/2.8 for $200 is just about impossible to beat.

The Sony 35mm OSS gives you slightly better performance optically, a wider aperture, and image stabilization for $449. At f/1.8 it’s pretty equal to the Touit in resolution and has less distortion.

Stopped down just a bit, to f/2.2, though, the Touit gives much better optical performance than any of the other lenses – numerically and by the eye test. Worth $900? To some people certainly. To others, not at all.

For me, taking actual pictures with it confirmed what the numbers suggested. The center resolution is probably the best I’ve seen from any lens on an NEX camera. That’s enough to make it a future purchase for me.

Roger Cicala

Lensrentals.com

May, 2013

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