Bokeh comparison between Sigma, Otus and Nikkor 58mm

Started Apr 19, 2014 | Discussions thread
TQGroup Senior Member • Posts: 1,340
Re: Bokeh comparison between Sigma, Otus and Nikkor 58mm

David Whysong wrote:

TQGroup wrote:

To me, the concept of "lens sharpness" is totally subjective and totally dependent on the situation being shot and the desired result. It is quite different to a lens "potential sharpness".

If that's the case, I have no idea what you mean by sharpness. I have a background as a professional physicist and astronomer, so I usually think of the point-spread function. But MTF works as well. Those are not subjective.

Of course one must understand the conditions or limitations of any test; but that doesn't mean lab results don't have application to practical use.

OK, let me try to explain. When photographing an older person, I've sometimes used a lens you have, the 85 F1.8G, I've acquired critical focus and then "backed off" a bit to create a softer, "blurrier" look. So, in effect, I find that 85mm "too sharp" for rendering aged / wrinkled / imperfect skin. Years ago, an old Zeiss F2 50mm Planar did exactly that for me at F2 without me having to focus manually and then "back-off". That lens "render" some timeless and evocative photos!

If you have older people in your family,say, past 80 years, you might find they won't complain if their photos are not so clinically sharp but they look good.

OTOH, in years gone by when it mattered, I sometimes craved for better resolution at the focused plane to get more "crispness" in very large prints. To me, the "sharpness" I need for a shot is totally subject and desired outcome dependent.

Understanding your profession, I can see where you are coming from and may I suggest that the Lens Tip site might be of interest... they are all about "optics" and not "photography" per se.

Unfortunately, "lab tests" do not necessarily predict lens behaviour at different, usually, longer distances. For example, the rightly acclaimed Sigma 35 ART is devilishly "sharp" up to about 5 metres; however, near infinity, it is still very good but not outstanding.

The increasing interest in lens performance, especially sharpness and the plethora of lens testing sites can have a perverse effect. It is possible that some lenses may be actually designed to "star" at typical lens testing distances; eg 40X focal length, so that they get eye catching "scores". This would be unfortunate and potentially mislead many.

David, I believe you may have a predisposition towards apparent "ultimate sharpness" and there is absolutely nothing wrong with that. May I also say I can understand your position but I do not share it for most of my photography.

Perhaps I can pose you a challenge: what is more important to your photography; image "recording" or image "rendering"?

It has never been completely clear to me what people mean by "rendering." I usually interpret it as primarily bokeh related, but also including color and contrast. But I worry that one might confuse a property of the lens with elements in the scene being photographed.

That said, I think the answer is "both" because these concepts are not independent. Think of "rendering" as being layered on top of "recording."

I want both a sharp plane of focus, AND quality bokeh; hence my lens selection and wish-list.

Subtle color rendering differences are mostly lost on me (I'm not color-blind though). Contrast can be adjusted in-camera which makes it less significant as a lens quality.

For several years I used the 85mm f1.4D exclusively, and I only stopped down beyond f2.8 on rare occasions. I bought the 85mm 1.8G during the recent sale and while the sharpness is nice, I'm not completely sold on its rendering.

These days my main photographic subject is my family. For that, I want nice rendering and not documentary-style photos. Even if the depth of field is very small, I still want the eyes sharp and shining -- and I don't think that precludes nice rendering.

To me "rendering", especially for people, is about having images that portray them in a more flattering manner... to make them look better than they might expect and so assist them to feel good / better about themselves. It is about photos that are remembered and treasured; ones that people go back to time and again... ones that are never "forgotten".

Great rendering involves good, flattering colour; not necessarily accurate colour. It involves a photos with "pop", one where the image "stands out" from the background; an almost "three dimensional" look. It usually involves very smooth OOF elements that help "project" the principal image towards the viewer, free of unwanted distractions.

Contrast may or may not be so important... it really depends on the final "look" the photographer has in mind.

Perhaps rendering can be explained another way; to me it is more about "painting" with light (with all the freedom of expression that permits) rather than "capturing an illuminated image".

As for eyes "sharp and shining"; well sometimes, especially for younger folk. However, soft, dreamy "ethereal" eyes do it very well for many, especially babies and courting couples, etc. A softer, wistful, reminiscing look doesn't go astray for older folk either. In short, for most family photography, "rendering" is about helping people look better than perhaps they might look in the mirror.

May I suggest that when the occasion suits, you rent the Nikon F2 200mm VRII for a family "shoot." You might want to have a monopod handy but the way this lens can render is absolutely gorgeous. Unfortunately, like most things optical, the trade-off is very heavy weight and high expense. But, for a special occasion, it is worth it!



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