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FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve ...
  
 
Parariss
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p.8 #1 · p.8 #1 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


Parariss wrote:
I'm glad you brought this up. I should have said something on this. The amount of friction of the focus rings isn't very different between the 70-300G and the 70-200GM (i.e. fine), but the focus ring design is entirely different, and the lens focus driver software also seems different to me.

On the G, the ring is narrow and nearer the camera. On the GM it's much wider and on the objective end. I suppose you eventually groove with the gear you have, but this inconsistency was unwelcome as I was switching back and forth. (I'd much rather deal with
...Show more


A footnote about focusing the 70-200GM, for anyone interested:

First, on every other Sony lens I've handled so far the focus ring is disabled when the lens/camera is being used in AF mode. On the GM, the focus ring continues to operate, at least partially. So, if you are in AF and you knock the focus ring accidentally you'll knock the lens out of focus. (You learn, but unfortunately this isn't hard to do.) If you're in AF-C, you can feel/see the manual focus ring fighting the AF focus motor. I haven't tested whether it's possible to focus fully and correctly with the manual focus ring while in AF, but you can see the focus being altered in the viewfinder.

Second, the GM focus ring spins 360 degrees, continuously without a hard stop. There is, however, a 'soft stop.' When you get to the end of the focus range, if you keep twisting there's a slight click and a slight increase in ring friction. I think the entire focus assembly is spinning inside the housing beyond this point. It's like a dial combination lock - if you open it slowly, you can feel it as the dial pick up the next locking mechanism inside and become slightly harder to spin the dial, safe cracker style. It's all very subtle.



Feb 12, 2017 at 11:21 PM
virtualrain
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p.8 #2 · p.8 #2 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


So I've since found a couple of other reviews that seem to indicate the Sony 70-200 GM is amongst the sharpest zooms ever tested...

https://www.ephotozine.com/article/sony-fe-70-200mm-f-2-8-g-master-oss-review-30557



And this Korean test... The RAW images available for download are prime sharp to my eyes and their own resolution test shows it hitting 4000LW/PH at all tested apertures and focal lengths.

http://www.slrclub.com/bbs/vx2.php?id=slr_review&no=547

I'm starting to have more faith that this lens is not a dud.




Mar 08, 2017 at 01:16 AM
virtualrain
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p.8 #3 · p.8 #3 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


Parariss wrote:
Adjusting the topic a bit, I'm still curious about the unusually large *disparity* between the testing results of the different sources. You'd expect different results from different methodologies, but this time we have everything from 'sharpest ever' to 'not good' to 'is something wrong with my test kit?' Pretty wild.

Maybe poor testing variances simply finally yielded a wide spread. On the other hand, a while back we had speculation that maybe the lens performed less well at infinity but really well at intended working distances. How might we test that theory, apples-to-apples? Other theories?


I have to think the testing distance has something to do with it, but even the Korean test I linked above offers some sample images of distant buildings taken at what must be infinity (one with the 2x TC) that seem to defy this as they are remarkably sharp.

We need more test results I guess. Something is not adding up.



Mar 08, 2017 at 03:52 AM
RCicala
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p.8 #4 · p.8 #4 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


virtualrain wrote:
We need more test results I guess. Something is not adding up.


Perhaps, but let's also look at what we do know, and perhaps remove a little internet hyperbole (shocking to consider, but it does happen).

On an optical bench the FE 70-200 f/2.8 is decent (nearly as good as the Canon 70-200 f/2.8 IS II, which is not as good as the new Nikon). Disappointing, perhaps but does not make it an awful lens. It is, for example, better than the Canon Mk I on the optical bench, which a lot of people still shoot with quite happily.

On some of the lens-camera combination tests it's truly spectacularly good, perhaps as good as the Nikon. Why perhaps? Some minor points.

1. A really good camera-sensor may pull these scores up. So you have to make sure you're comparing the Canon 5Ds or Nikon D810 when you pull up someone's test results on DxO or an Imatest lab. And even then the A7rII is higher res than the Nikon, a bit lower than the Canon.

2. Some of the lab scores are testing jpgs and in a few cases they're oversharpened. (I'm not going to open the argument about whether jpg testing is valid, but oversharpened jpg testing is definitely not. And with high res sensors we get some oversharpened jpgs at the factory default setting, and perhaps less.) When the resolution presented is greater than diffraction limits, even if the author claims it's an unsharpened jpg, the test is invalid, but boy oh boy, do we present that result over and over if it says what we want it to say.

3. Sony cameras probably manipulate the raw images to some degree. We know it is so for distortion and vignetting in some lenses. It may or may not be true for sharpening, I don't know for certain. But this would make the target testing results invalid.

A technical point too. As a general rule sharpness and variance at infinity and closer distances are the same. But there are some reasons this lens may be different. First among these is it has two very strong aspheric elements. One of these is in the image stabilizing unit (unusual), the other is in the rear focusing group (quite unusual) and the two are right next to each other (very unusual). More to the point, putting two aspheres next to each other requires very tight tolerances in general, yet these two groups are both moving groups.



What does this mean? I'm not sure yet. We would expect it to mean higher variation in theory, but we don't know in what way or if Sony has developed some technology to overcome it. But it could also mean this lens is going to perform differently at infinity or close up, both in sharpness and in variance. It could mean the lens is going to vary depending on the stabilizer's position and the distance the focusing group is from the asphere. And to make it more interesting, we don't know the exact how that rear group performs because it's electrically encoded, so it may not be as simple as 'at this zoom and this focusing distance' it does this. It may be very active at certain focal lengths and not at others. It may move a lot close up or near infinity, but not at all elsewhere.

What is the bottom line (well, except for fanboys, and Sony Fanboys are rapidly passing Nikonians as the most illogical group on the internet)? For almost anyone who needs a 70-200 f/2.8 lens this is the best choice. It may not be as 'bestest' as we want it to be. It's pricey. But after all the wailing and gnashing of teeth, it's the best choice.







Edited on Mar 08, 2017 at 01:57 PM · View previous versions



Mar 08, 2017 at 12:37 PM
 

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ggreene
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p.8 #5 · p.8 #5 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


RCicala wrote:
and Sony Fanboys are rapidly passing Nikonians as the most illogical group on the internet


Now that got me to chuckle.



Mar 08, 2017 at 01:56 PM
RCicala
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p.8 #6 · p.8 #6 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


virtualrain wrote:

So I've since found a couple of other reviews that seem to indicate the Sony 70-200 GM is amongst the sharpest zooms ever tested...

https://www.ephotozine.com/article/sony-fe-70-200mm-f-2-8-g-master-oss-review-30557

https://www.magezinepublishing.com/equipment/images/equipment/FE-70200mm-f28-GM-OSS-6018/large/Sony-70-200mm-f2-8-GM-MTF70mm_1486459404.jpg


And this Korean test... The RAW images available for download are prime sharp to my eyes and their own resolution test shows it hitting 4000LW/PH at all tested apertures and focal lengths.

http://www.slrclub.com/bbs/vx2.php?id=slr_review&no=547

I'm starting to have more faith that this lens is not a dud.



I find it very difficult to believe (especially since their methodology isn't clear) how they find the MTF at the edges equal to the MTF at the center. And moreso since they show 1.5 to 2 pixels of lateral chromatic aberration, which must, according to the laws of physics, affect MTF. I may well be missing something. Or they may be testing jpgs and Imatest picking up the sharpening artifacts, which it will do if you don't check carefully to make sure it isn't. Finally, my math may be off, or they may not be presenting MTF50 (they're very vague) but I think 4k lp/ih exceeds the theoretic possibility of the sensor.

Other than that I think it's great.




Mar 08, 2017 at 04:11 PM
virtualrain
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p.8 #7 · p.8 #7 · FE 70-200/2.8 GM: Sharpest and best low-light zoom we’ve tested


RCicala wrote:
Perhaps, but let's also look at what we do know, and perhaps remove a little internet hyperbole (shocking to consider, but it does happen).

On an optical bench the FE 70-200 f/2.8 is decent (nearly as good as the Canon 70-200 f/2.8 IS II, which is not as good as the new Nikon). Disappointing, perhaps but does not make it an awful lens. It is, for example, better than the Canon Mk I on the optical bench, which a lot of people still shoot with quite happily.

On some of the lens-camera combination tests it's truly spectacularly good, perhaps as good
...Show more

Thanks for taking the time to reply Roger. What you're saying makes perfect sense. I think the first MTF testing you did was a bit of a shock to everyone (including Sony I'm guessing) and as one of the first tests of this lens, really got this lens off on to a bit of a negative start amongst enthusiasts. However, as more and more tests surface, it seems to support what you're saying that there are perhaps some nuances to this lens that can affect its performance (for better or worse) under some circumstances. And at the very least, this lens is a good choice and a decent performer, if not outstanding in some situations.

---------------------------------------------

RCicala wrote:
I find it very difficult to believe (especially since their methodology isn't clear) how they find the MTF at the edges equal to the MTF at the center. And moreso since they show 1.5 to 2 pixels of lateral chromatic aberration, which must, according to the laws of physics, affect MTF. I may well be missing something. Or they may be testing jpgs and Imatest picking up the sharpening artifacts, which it will do if you don't check carefully to make sure it isn't.



That could be. It's good to know.



Mar 08, 2017 at 05:02 PM
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