Opinions on f/1.2

Started 2 months ago | Discussions thread
anotherMike Forum Pro • Posts: 10,704
Re: Opinions on f/1.2

I think I detect two sub-questions here:

  1. What is the real world worth of having a lens with F/1.2 aperture
  2. What is the Nikon 50/1.2S specifically like as a lens.


I can't answer whether F/1.2 is required for your work. Honestly, it's not for mine. But if I still shot theater/live dance, yes, having F/1.2 would be a big thing. If I shot astro (I do not), it might be a big thing. If I really liked the super thin DOF "look", which perhaps at times I find useful but certainly not always, having F/1.2 would be nice.

The advantage of the F/1.2 lens (assuming it's designed well, which the Nikon one is) is that you generally get better bokeh and better OOF transition quality at the group of wider apertures. In other words, it's not required that one shoot an F/1.2 lens wide open and only wide open to utilize what it does well. Additionally, since F/1.2 lenses in the manufacturers line are generally higher end lenses, quite often we'll see performance improvements even at intermediate apertures (this is true of the Nikon 50/1.2S)

So that's my attempt at an answer to the F/1.2 question.

Now let's talk about the Nikon 50/1.2S lens specifically:

As a general rule, when Nikon does a higher end lens with an intent that it be used for people photography amongst its use cases, the designer will often tune the lens differently for work in shorter/moderate distance ranges compared to moderate/longer distance ranges. This is critical to understand - I repeat - critical - because so many of the so called "tests" as well as the generally worthless "10 sharpest lenses" youtube videos are done in closer test range, where it's quite likely that a candidate lens was *intentionally* tuned to trade away "ultimate sharpness" for bokeh and OOF transitions. Most all Nikon lenses from the G series on up through the S line have this approach - to varying degrees - if the lens has been determined (by the designer) to be used for people. Note clearly that at moderate/longer distances, the tuning "goes away" and the lens is generally pretty sharp, although there are still differences.

I should inject that when I say "ultimate sharpness", I'm referring to, using MTF optical bench measurement terms, mid/high and high frequency performance, and not low frequency performance, which can be thought of as a rough proxy for what we often call "contrast". This means that lenses tuned for people work will *not* "win" the MTF50 test chart battles, nor will they likely place highly in the "10 sharpest" lens videos conducted in closer range - because they weren't designed to. And if you think about whether a) you desire ultimate resolution AND b) whether the scenario (due to focus inaccuracy, motion blur, etc) will *allow* you to achieve ultimate resolution, then you can see that the design approach (the trade off for bokeh and OOF transition quality) makes sense *for people*. Obviously it would NOT make sense for other tasks, which is why we must always think (and talk) tool for task when discussing lenses.

I do view the 50/1.2S as a specialist tool more than a generalist tool. It is *very* large, and it's not cheap. There are a lot of misconceptions thrown about as to why it's large, but the reality is that the designer, in order to achieve his bokeh/OOF transition/rendering goals in the people use cases, chose a symmetrical optical design which gave him advantages he could not achieve with a smaller (shorter) lens. This lens has nice bokeh both "fore and aft" of the focus plane: most lenses only aft, as one example. From a rendering perspective, the designer has mentioned in interviews that in the closer (portrait) ranges he didn't want it to be unnaturally sharp with a bad falloff, which explains why he purposefully supressed the mid/high frequency performance in closer distance ranges. It will never "beat" many competing 50mm lenses in the test chart game. Wasn't meant to. He also mentioned, in interviews, that he paid a lot of attention to the balancing of the various components of sharpness, meaning that it has an excellent balance between coarse (low), medium, fine and very fine structures in an MTF sense. Note that most writing on image quality (Otto Schade from RCA to use one example) believe that image quality is NOT defined by a single sharpness point on a graph of score. I share this belief - the rendering of the best lenses comes from very well thought out balancing of the aberrations which results in the balance between the resolution components just as much as the OOF transition or bokeh quality.

So in portrait distances, in the people use case, it's unbeaten in the 50mm category. Bokeh is wonderful, transitions and the overall image is natural and unforced, and things look realistic and dimensional. The designer also (I've measured this to see) changes the "tuning" as the distance increases - the further you go from "head shot" to "full body", the less emphatic the tuning is. He put a lot of thought into how the lens should image people in the traditional range of portrait/body distances. In many ways, I think it's his statement lens, one to mark his career with.

HOWEVER, it's a two personality  lens. As distances increase to the moderate, the tuning goes away, and the balancing of resolution components is more even and less emphatic to the coarser structures (somewhat speaking). I've found that at early intermediate apertures, the broad, and I mean a hell of a lot of the frame broad, central zone can *easily* meet that of the reference lens around this focal length, the Sigma 40/1.4 Art, and in fact, I think it might *exceed* it, which is really serious praise indeed. At landscape distance, at F/4 or F/5.6, I'm not sure I've *ever* seen broad central zone performance at distance like this lens, and I've been around and used *a lot*.  It's something else, and it's in *this* aspect that it also moves ahead of the already pretty good 50/1.8S. It's likely near diffraction limited through a lot of the frame, meaning it has nothing to fear (at distance) from any other design, from Sony to Voigtlander, because that's as good as it gets and that's that.  I'm hugely impressed with it's distance capability.

Add in tremendous flare resistance (better than any Sony, Zeiss, Voigtlander or Canon 50 and easily so) and you've got a compelling lens.

However, a prospective purchaser needs to *clearly* be aware of the portrait specific tuning at the closer distances - if one expects "apo lanthar sharp" performance at closer ranges, this is NOT your lens; it's a portrait lens up close to close/moderate, and then a world class, nothing is better, landscape lens at moderate/far to far distances.  And the thing is big and expensive. Not a lens for everyone. Wasn't meant to be I don't think.

So we're back to matching tool for the task, as always.

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