Bokeh comparison between Sigma, Otus and Nikkor 58mm

Started 8 months ago | Discussions thread
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Re: Bokeh comparison between Sigma, Otus and Nikkor 58mm
In reply to TQGroup, 8 months ago

TQGroup wrote:

David Whysong wrote:

TQGroup wrote:

David, your gear list shows you own some incredibly fine glass... surely you can see more in an image than just "sharpness"?

Perhaps you could help me understand your opinion better by precisely explaining what you mean when you say "the lens is not sharp"?

Thank you

Andrew

You were looking at my gear *wishlist*. I have a Nikon 180 AF, 85 1.4D, 85 1.8G, and a Sigma 35 Art. Those also qualify as nice glass, but it's not what you saw in the gear list.

Sharpness isn't everything one might want from a lens, but a sufficiently sharp focal plane is the most fundamental requirement of a lens.

Down-sampling is nothing more than throwing away resolution that the lens failed to deliver.

I love some of the pictures I've seen posted here from the 58, but I don't think its image quality is any better than the old Sigma 50 which costs about 4x less, achieves better sharpness, and provides similarly excellent bokeh.

I see a lot of people making claims related to bokeh quality of the Sigma vs. Otus vs. 58mm, but it's almost impossible to properly judge without a side-by-side comparison. Here we have one, and while there is a visible difference in bokeh, none appear perfect in this example. (On further inspection, I do see differences between the Zeiss and Sigma; I'd say the Sigma looks a bit better but it's a close call.) However the 58mm is noticeably unsharp even in this very low-resolution image!

David

I agree with a lot of what you write but I do see a dichotomy.

You very rightly say; "Sharpness isn't everything one might want from a lens, but a sufficiently sharp focal plane is the most fundamental requirement of a lens".

Then, your last sentence says; "However the 58mm is noticeably unsharp even in this very low-resolution image!"

There is no dichotomy in David's position. Where is the dichotomy in 'A lens should be sufficiently sharp at its focus point, however, the 58/1.4 is not sharp anywhere in the image at 1.4 or even at 2.0'?

In my prior post I wrote: "Perhaps you could help me understand your opinion better by precisely explaining what you mean when you say "the lens is not sharp"?"

Can you see my challenge? It is how to accurately interpret your concept of "sufficiently* sharp focal plane"! (* my underscoring and italicization)

It's safe to say that blurry (as seen in the 58/1.4 examples) is not "sufficiently sharp" by anyone's standard.

To me, the concept of "lens sharpness" is totally subjective

Lens sharpness is not a "concept" and there is nothing "subjective" about it, at least from a 'user' point of view. It's a reality of Physics determined by the lens' design and its quality of manufacture, and is easily measured by tests. Differences in sharpness are easily observable by the human eye.

and totally dependent on the situation being shot

Perceived lens sharpness is very dependent upon the lens' ability to discriminate between pure black and pure white (contrast), so any lighting situation (strobes, Sun, street lights, etc.) that would cause flare or lack of contrast will reduce perceived sharpness. All lenses suffer from flare and lack of contrast in difficult lighting situations to one degree or another. Some handle it much better than others.

Again, that's a function of the lens' design and is a trade-off determined by the stated goals of the lens designers and constrained by the lens' cost.

Which is why lenses are tested using uniform testing methods under ideal lighting in order to determine the sharpness of a lens. That way 'Lens A' can confidently and accurately be said to be sharper than 'Lens B'.

Situations that cause lens flare or other adverse lighting conditions are rare in real life situations, and can usually be avoided or lessened for the most part.

It is quite different to a lens "potential sharpness".

Lens sharpness is lens sharpness. The sharpness of a lens doesn't change because the user doesn't employ proper technique. Camera movement or vibration from the mirror is user error in producing a usable image and has nothing to do with the sharpness of a lens.

There's only one way to determine a lens' sharpness and that is to employ proper technique, yet you bemoan such proper technique (technique that amateurs strive to employ) below as being nothing but trickery and deceit utilized by testing sites to fool the new and naive.

The concept of "potential lens sharpness" in a laboratory setting under controlled conditions and at a distance of 40 X the focal length, etc, etc is of academic interest for the most part as virtually all good quality modern lenses are sharp enough for all but the most demanding assignments. And those who get those assignments know what they need and why they need it.

In fact, I am starting to believe that MTF, as in MTF Chart, is really an abbreviation of Meaningless, Titillating and FUDing

Meaningless: MTF charts are shot of a flat subject,

That's because the only way to properly assess field curvature or to determine if a lens has a de-centering issue is to shoot a flat subject.

usually black & white

That's because the only way to accurately determine a lens' ability to discriminate contrast (the difference between pure black and pure white) is by shooting a black and white subject.

over distances of 40 X focal length or so

That's because there needs to be a standard distance at which lenses are tested, and because all lenses should perform optimally at that distance, even macros.

from heavy tripods with remote releases,

Perhaps you would prefer the camera and lens be hand held by a 6 year-old while walking? The sharpest lens in the world would appear dismally blurry if that were the case.

mirror-up for 4 seconds under controlled and even lighting conditions, etc, etc.

I know! Imagine the gall of testing sites to employ such ridiculous methods when testing a lens for sharpness!

Honestly, now who actually takes pictures like that in real life!

Those who care enough about their photography to shell out $950 (Sigma 50/1.4), $1,700 (Nikon 58/1.4), or $4,000 (Zeiss Otus). One would hope, anyway.

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