Lenses and Optics

Nikon 70-200mm f/2.8E FL ED AF-S VR MTF Tests

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Published November 21, 2016
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Olaf Optical Testing, 2016
Olaf Optical Testing, 2016
Olaf Optical Testing, 2016
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Well, we all want to call it the 70-200 VR III, since it replaces the Nikon 70-200 f/2.8G AF-S VR II.  But the new lens is officially the 70-200mm f/2.8E FL ED AF-S VR. It is most definitely a different lens; it’s 22 elements include one fluorite, one high-refractive, and six ED elements, along with new coatings. There’s also fluorine finishes on the front and rear elements to prevent smudging. I’m not a fan of this in general (they seem far more prone to coating scratches), but some people are. Not to mention it has electronic aperture control (of which I am a fan). And, of course, an improved 4-stop VR system.

So most of these improvements are things you’ll need to find out about in lens reviews, which this isn’t, if you’re considering upgrading to this lens with it’s Sonyesque $2,800 price tag. I’m just here to tell you how it performs on an optical bench, what it’s resolution is, and stuff like that. Maybe in a few weeks, we’ll take one apart and look into that ‘improved weather sealing’ claim. But for today, we’re just going to look at the optics.

nikon-70-200-e-2
I’m quite interested in how this lens performs. The VR II was an exceptionally good lens at 70mm, really rather weak in the middle of the zoom range, and then got superb again at 200mm. Nikon’s marketing department is waxing poetic about the improved optics of the new version, so I was pretty eager to see these poetic MTF curves for myself.

MTF Results

To make things simple from the start, I’ll compare the MTF curves for the new FL lens on the left to the MTF curves of the Nikon 70-200mm AF-S f/2.8 G VR II lens on the right.

At 70mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

The 70-200mm VR II was at its best at 70mm, and the new lens is even better on the MTF bench, although just a bit. I doubt that anyone is going to notice much difference in their photographs, but they might see improved corner sharpness.

 

At 135mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

The 70-200mm VR II was at its worst at 135mm, and the new lens just mops the floor with it in the middle of the zoom range. It’s not just hugely sharper in the center; it’s sharper 2/3 of the way to the edge of the image than the old one was in the center. Now I know a LOT of people use their 70-200mm lens just as a 200mm lens, but honestly, if you ever visit the middle of the zoom range, you will notice this difference. It’s night and day.

 

At 200mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

The VR II was quite good at 200mm, particularly at the center. The new FL lens is perhaps a bit better in the center, but it maintains its sharpness much better as you go away from the center. Maintaining sharpness this well away from center is pretty amazing for a zoom lens.

I’m going to have to talk about this MTF curve a bit, because you may have noticed that the sagittal and tangential curves (dotted and solid lines) aren’t quite together in the center of the FL lens, which is unusual. The reason, in this case, is a bit of ‘off-centering.’ I’m not going to use the word decenter, because that implies optical decentering, which this isn’t, exactly. Rather the sharpest point at 200mm is, for most copies, not quite at the center of the image, but just a few mm (in sensor distance) from the center.

Remember, the graphs I show you are averages of 10 copies, each of which is averaged at four rotations; so the average of 40 MTF curves. If you look at a typical single rotation MTF reading they mostly look like this:

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

So technically, all of the 10 copies we tested were very slightly decentered at 200mm. But we usually think of decentering as causing a soft image, and in none of these lenses could the image be considered soft. It’s rather that the area of maximal sharpness was just a bit away from the center.

Because the sharpness is maintained so well from side-to-side, I very seriously doubt anyone could find that the center was a bit off-axis in a photograph in any of these ten copies. That doesn’t mean there aren’t going to be some that are significantly decentered at 200mm, though, because lots of lenses made. But again, decentered or not, they were all just damn sharp at 200mm.

Field of Focus Curves

I wanted to post the field-of-focus curves, for those of you who are interested in the geeky stuff, to show just how flat they are. Again, this would be good in a prime lens, but for a zoom they’re pretty spectacular.

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

This is one copy, but a very typical copy. And yes, most had a very slight field tilt at 200mm, but little or no tilt at shorter focal lengths. Again, you can harp on the negative, but for a zoom, this less field tilt is less than we expect to see.

OK, Fanboys, Here You Go

nikon-70-200-e-4

Yes, I hate myself for doing this but if I don’t someone is going to dig up old results and do it anyway. What follows is a comparison of the Nikon 70-200 f/2.8 FL VR to the standard bearer of 70-200 f/2.8 lenses, the Canon 70-200 f/2.8 IS II.

At 70mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

The new Nikon is a tiny bit better in the center but definitely is a bit better off-axis in the middle frame at 70mm.

At 135mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

This demonstrates just how much of a difference Nikon has made in the middle focal range. The Canon was clearly better than the Nikon VRII, while the Nikon FL is clearly better than the Canon.

At 200mm

Olaf Optical Testing, 2016

Olaf Optical Testing, 2016

Despite the oddity in the Nikon 200mm graphs, I think the Nikon is clearly a bit better at 200mm. As always, let me emphasize this is ‘lab better.’ Actual photographs with all of the variables that introduce, I doubt the difference at 70mm or 200mm would be of any visible significance. At 135mm, though, I think they might be.

And as always, this has been an MTF test; it was only an MTF test. Had this been an actual photograph you would have been instructed that all differences were simply because of poor technique.

Roger Cicala and Aaron Closz

Lensrentals.com

November, 2016

Author: Roger Cicala

I’m Roger and I am the founder of Lensrentals.com. Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

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  • donpnz

    Thanks Roger! I’m saving the $$. Happy days..Nikon getting something right

  • Jonas

    Is your optical bench equipped with a Porsche mount?

  • bdbender4

    Hmm, well a Porsche test would have to be in secret.

    Hypothetical: I set up a test with Porsche for you, and of course I would come along (we’re talking REALLY hypothetical here, I am not in any position to do that).

    We get back to the showroom, and try to have a conversation about what we just found out. If it wasn’t in secret, a whole crowd of BMW fans (and a few Alfa die-hards) would come flooding into the Porsche showroom, and start having a loud unending ongoing conversation about BMWs, including really geeky technical BMW cylinder head details. The Alfa folks would try to be heard saying “hey, Alfa makes the best cylinder heads and has for years and years”.

    This would make it darn tough to have a useful Porsche conversation. Just sayin’. 😉

  • HF

    Doesn’t matter. Based on the input data it achieves the goal by using information in a feedback loop to achieve focus. Whether this is the true focal plane or not is irrelevant for the method being in use.
    The exact focus plane can’t be found MILCs, too. Focus is where our numerical algorithms think maximum contrast is located. Depending on the size of your focus point, this changes. Depending on light, this changes (esp. if noise creeps in). Lens motors are not perfect, too. People in contact with camera developers confirmed the closed loop approach.

  • Peter Weir

    That article would have a bit more credibility if it addressed /why/ an AF microadjustment-like calibration is necessary if an SLR AF system is, as the article author claims without any real substantiation, closed loop.

    Unfortunately, the only way the article author addresses the issue is thusly:

    “[..] I’m not trying to explain why a closed-loop system requires lens calibration for accuracy. For the purpose of this article, I accept the fact that lens calibration is essential for accurate focus, whether the system is open or closed-loop.”

    Nice way to elude the ESSENTIAL issue. The author apparently doesn’t even realize that the “closed loop” system he describes can’t even detect that actual, accurate focus is achieved, hence the need for “solutions” like “calibration”, “offset”, “microadjustments” to compensate e.g. for lens variations.

    What the article author says, in essence, is that “if we ignore the accuracy errors (which require e.g. calibration to be eliminated), then there are no accuracy errors in a SLR AF system. Ergo, as we decree that there are no accuracy errors, the system must be closed loop”.

    #FAIL

  • Thank you Peter. That’s exactly the kind of thing I considered when I decided to hold those results. Our process, I THINK, should be accurate (it is for other Sony EM focus lenses): We set the lens to infinity focus via the camera, then fine-tune focus with the optical bench. It works fine for the others. But the others aren’t twin motor so there is that question.

  • HF

    I don’t see the purpose of writing the many obvious things down here. In addition regarding open-loop look here:
    https://www.dpreview.com/articles/5402438893/busted-the-myth-of-open-loop-phase-detection-autofocus

  • Peter Weir

    The Sony 70-200 GM might be a quite difficult lens to properly test on an optical bench.

    As you mention, the GM contains two focusing motors:

    1) a ring ultrasonic motor, similar e.g. to Canon’s USM, driving lens elements located near the front of the lens

    2) a linear motor driving lens elements located closer to the bayonet mount.

    In a phase-detect AF system, the body’s AF unit determines the lateral optical distance — a.k.a. “phase” — between the current lens focus position and the desired focus position, and then orders the lens to move that distance. The lens’s built-in AF controller translates that lateral distance information into the concrete, focal distance-dependent mechanical longitudinal movement of the lens elements that would, in theory, cancel the lateral phase difference.

    From a control theory point of view, a SLR’s PDAF system is an “open loop” system, where the SLR doesn’t check if the distance moved by the lens elements actually achieves the best focus. The camera and lens system just assume that the initial phase distance information is always translated into a perfectly matching lens movement. That assumption was maybe sufficient during the film era, but the increasing resolution of digital cameras has made more and more apparent that there may, in fact, exist a residual focus error after the lens has executed the focus instruction sent to it by the body. SLR manufacturers have tried to compensate for that by introducing e.g. AF micro adjustment facilities in their bodies that allow the user to somewhat adjust for the focus veriability occuring with their specific camera and lens combinations.

    Mirrorless cameras typically have a contrast-detect AF unit. In a CDAF system, the camera instructs the lens to “wobble” its position, and determines the direction and position of best focus by examining the actual picture sharpness variation at the chosen focus point. A CDAF system is thus, inherently, a “closed loop” system that repeats the “measure defocus and then move the lens” process until the best focus is actually achieved. Thus, CDAF doesn’t require gimmicks like AF microadjustments. A CDAF system also has a few disadvantages:

    1) the iterative focus approach can make CDAF slow compared to PDAF systems

    2) a lens designed for CDAF should have a focusing mechanism that efficiently supports the tiny to-and-fro movements required for the wobbling AF convergence process. Conventional, unit-focusing lenses where the entire optical system must be repeatedly accelerated from standstill, then accurately stopped, are diasdvantageous for CDAF, as their high inertia would require very powerful, energy-hungry motors to implement high-speed wobbling. CDAF lenses thus often have an internal focus lens design, where only a lightweight, and therefore light inertia lens group is driven longitudinally by a linear AF motor.

    At the Photokina a few weeks ago, I had an interesting chat with someone at the Sony stand about that lens.

    I asked him whether the ring USM was used only with PDAF-capable bodies like the Sony A7RII, A7II, A6500, A6300 etc., and that the linear motor near the rear of the lens was intended for CDAF-only bodies like the A7R and A7S. He explained that it wasn’t the case, and that the Sony 70-200 GM actually uses the two motors even with CDAF bodies. The linear motor is used, he said, to implement a novel, electromagnetically- instead of helicoid-driven “floating element” aberration correction system. Floating elements typically implement a tiny variation of the distance between select lens elements in what is, otherwise, a conventional unit-focusing lens. This variation is designed e.g. to compensate the subtle aberration pattern changes that occur e.g. between infinity and minimal focus distances. As the minute lens movements require more complex, and very accurate focusing helicoids, floating elements were typically implemented only on high-end, expensive lenses — e.g. 28/1.4, 85/1.2 etc.

    The 70-200 GM takes advantage of the fact that all Sony bodies, even if they have PDAF sensors, can use CDAF to optimalize the focus point. The ring USM, linear motor and camera CDAF thus work in concert to achieve the best focus position and minimize aberrations by driving the “floating element” using a linear motor, in a “closed loop” fashion, using feedback from the camera body.

    I think one consequence might be that an optical bench would have to accurately emulate the CDAF-like “closed loop” mechanism to tell the 70-200 GM’s linear motor-driven floating elements to “wobble” and slide to the proper position required to minimize the residual aberrations at the selected focus distance — e.g. infinity…

  • Brian Smith

    You are correct. I meant to say Canon (with adapter) vs Sony. Yes, the adapter “may” play a role and work against the Canon. That being said, if the Canon with an adapter is much sharper than the native Sony that says a lot about the performance of the Sony.

    Of course you could throw in the Nikon (with an adapter) or just compare it on say a D810 just for fun.

    For what it’s worth I think your results will remain roughly the same based on the images posted thus far on other sites. So far they have been mediocre, at best. Some actual owners are reporting hit or miss behavior with focusing as well.

    Regardless, I’m pretty sure I speak for many when I say we would love to see a real world comparison with adapters. Perhaps a portrait shot and then a fixed landscape shot?

    I’m super disappointed I waited 3 months for most likely what will end up being an overpriced, underperforming lens. 🙁

    Thanks Roger!

  • Wouldn’t that involve 3 different cameras? Hardly apples to apples. It would be a good system to system comparison, and I guess there are some people deciding which system they want.

    But I have suggested some of the phototechs shoot all 3 on a Sony camera with adapter. The adapter adds another variable, of course, but it has some good practical implications.

  • Ed Bambrick

    Roger, why not appease the prime fans and compare the new Nikon with the usual suspects?
    Otus 85mm, the new Nikon 105, the Apo 135 and the Nikon 200mm. Maybe some of us are willing to carry 20 lbs of lenses.

  • Brian Smith

    Would it possible (time wise) to take all three lenses in question (Canon/Nikon/Sony) and focus on a detailed scene and post the images for comparison. This would be an apples to apples comparison.

  • TOGA!! TOGA!!! TOGA!!!!!

  • Carleton Foxx

    You are like the Galen of the optical world—you heal the worried souls of photographers as you deftly slice away the tumors of internet folklore and lance the boils of outdated belief. When are you going to open your lens lamasery so that we can all come and sit around in togas and drink wine out of rams’ horns while you sing Zernike polynomials set to music.

  • You can get a bit of an idea from the field of focus graphs – the color fall off is a reasonable representation of how sharpness falls off.

  • Lee

    Thanks for the update, Roger! Quite the dramatic difference, that’s always exciting to see. I was expecting progress more in the “small but definite” range (if not the “hmm I guess it’s better in some ways? *shrug* ” territory of the 24-70E).

    Nikon does seem to be on a good run at the moment. Maybe the Art series and the 35L II scared them straight.

  • Carleton Foxx

    One of the characteristics of a great lens is the clean, gentle way that it handles the falloff between in-focus and out-of-focus; especially when it comes to faces. Is there a way to tell from these charts which lenses might possess that quality?

  • I think there’s another thing worth considering here that I didn’t mention. An early batch of 70-200 GMs came out and then the supply seemed to dry up. I honestly will want to test another batch of 10 later before I make any conclusions. And just so I’m clear, I have absolutely no knowledge of why availability seems to have slowed to a trickle. But just because it’s the way I’m wired, I’ll want to test another 10 copies after we get resupplied before I make any definitive statements.

  • Let the record show I am completely willing to test a Porsche Carrera G. Porsche? Are you listening Porsche?

  • Phil, you know I don’t do like actual useful tests 🙂 But I bet 6,234 lens reviewers are gong to measure that to the nanometer.

  • I’m a ‘good lens’ Fanboy!

  • bdbender4

    Sony. Sony Sony. Sony Sony Sony.

    I’ll say it a little less politely than Roger did, below. This is a Nikon test. If you have been here before, you know that jumping on the bandwagon to ask Roger to test this that and the other thing is just not helpful, and can preclude a useful discussion of the test itself. So please don’t.

    “Hey Roger, can you test the Porsche Carrera G? How about Swarovski binoculars, in comparison to Zeiss?”

  • I’m trying. Can’t keep the 85 in stock long enough to test it. 🙂

  • Søren Stærke

    Nice comparisons Roger, some really stunning results come to think of it.

  • bdbender4

    No offense, but I just wonder why anyone who has been here before asks: Hey Roger, can you test this that and the other thing? Sony fans, I feel your pain, but this is a Nikon test.

  • Peter Kelly

    “I’d rather not see them reproduced all over the internet yet”?

    I think your hope is about as likely as emptying a bucket of mercury with a sieve!

  • Phil

    Hi Roger. Very useful information as usual. But what about the focus breathing? That was in my opinion the biggest flaw in the second version. Also, can you comment on the light transmission?

    Thanks!
    Phil

  • Andrej Belic

    What’s up Roger, did You become a Nikon Fanboy? You are going to upset the Canonistas 😉

    Just joking, I’m a huge fan of Your website and please go on with direct comprisons

  • Please test the new Sigmas!!!

  • bala

    The beauty of Sony mirrorless cameras is that they, as some people put it, have a ‘universal mount’ – there are adapters available for pretty much any mount out there. Here’s one that’s been recently announced for Nikon mount
    https://www.dpreview.com/news/4063594549/fotodiox-introduces-full-automatic-nikon-to-sony-e-adapter
    So, now you can adapt this beautiful Nikon lens to your Sony camera.
    Recently I bought a Canon EF 24-70mm f/2.8L II USM lens instead of Sony counterpart for my A7R2 because it’s cheaper and also I have a Canon 80D, which I can share this lens with now.

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