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I've just ordered a Zeiss Jena Pancolar MC 50mm prime lens, and have been reading up as much as I can about how to get the best quality images from it.

It's my intention to use it mainly with 3 different film SLRs, but occasionally with an APS/C Samsung mirrorless.

As I understand it, the sharpness on this lens is most crisp in the centre of the frame (as with my other 50mm lenses really), but I can't find much information on the way the lens behaves at different f-stops with regard to sharpness around the edges of the frame.

I realise that it is very subjective to ask how to get high quality images, but I'm curious if anybody with experience of these lenses has any tips on how to ensure as sharp an image as possible.

Mostly, I tend to photograph scenes of industrial decay, landscapes, and various wild plants and flowers in reasonably bright sunlight, however as the uk weather tends toward dim days for a lot of the year, I find that I'm often taking shots in much lower light than I'd like.

When I'm photographing plants, I tend to place the subject close to dead centre so this isn't too much of a worry for me, but when I'm photographing buildings or industrial scenes, I like to get as much of the edge of the frame in sharp focus as possible. One a session in Wales, it was fairly dark so I had the lens wide open (in this case, it was a Fujinon 55mm) and found that there was noticeable loss of sharpness at the edges of the shot. Stopping down a little and shooting for longer resolved this nicely.

I'd be grateful for any tips from anyone who has used one of these lenses in the past. I'm flying a little blind as on paper it seems like a superb lens, but I don't know anybody personally who has used one to consult.

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As a rule-of-thumb, the sweet spot for maximum sharpness is about 2 f-stops stopped down from the lens's maximum. At wide-open, a lens is usually slightly degraded because the peripheral figure (shape of the curve) is quite steep -- thus image-forming rays originating there are more likely to go astray. As you stop down, the figure is more gentle. However, as you stop down, the twin plagues of diffraction and interference begin to take a toll on acuity.

  • As a physics enthusiast, that answer appeals to me greatly, thank you! That's a really good rule of thumb to know, and it does explain why my Yashinon 50mm seems sharper at 11 than 16. Would I be right in assuming that the thinner the glass of the whole lens, the less significant the amount of diffraction, or is it wholly related to the curvature? – Alex Mar 1 '18 at 15:11
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    @Alex That sounds like a new question :) – mattdm Mar 1 '18 at 15:59
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    Diffraction relates to the size of the aperture at the diaphragm which is inside the lens. The glass itself is not an issue. – StephenG Mar 1 '18 at 16:00
  • @ Alex -- It unusual, you should retest! Surf the net for Rayleigh Criterion. The resolving power of a lens for the center wavelength of visible light is 1392 divided into f-number. Thus for f/2 = 696 lines per mm for f/4 = 320 for f/16 = 87 lines per mm. The reduction in resolving power is due to the devastating phenomenon of diffraction and interference. Do check out Lord John Rayleigh 1842 – 1919 Nobel Laureate. – Alan Marcus Mar 1 '18 at 16:06
  • @ Alex -- Diffraction is induced when light wave fronts brush the edge of the leaves of the aperture stop. Near contact causes a redistribution of energy within the wave front. These now ricocheting rays comingle with the image forming rays producing a series of closely spaced bands with a light then dark pattern. Diffraction is devastating as it robs acuity and contrast. – Alan Marcus Mar 1 '18 at 16:20
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In addition to Alan's info, this site did a review and compiled an MTF chart for the lens, which you may find of interest. In your lenses case, the sharpest test seems to be at f/5.6, or 3 stops down from wide open.


On lens sharpness as a whole...You can compare MTF charts to get an idea of relative sharpness comparisons between lenses. Some examples:

Canon 70-200 f/2.8 II:

enter image description here

And this is the 85 f/1.2 II:

enter image description here

You'll notice that at every measure, the 70-200 is sharper, or at least, produces more line pairs. As it should, it's one of the sharpest lenses ever made.

However, the 85 is the prized bokeh king in the Canon lineup.

So the question is, is sharpness everything? And now, the subjective argument can commence.

I think the important thing to note is that you should learn your gear, where it excels, where it falls short, and shoot accordingly. That 85, for example, doesn't resolve all that well at f/1.2 - but that's precisely the aperture that people buy it for.

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    You should probably point out that the MTF charts are done with each lens wide open. Thus the 85/1.2 is measured at f/1.2 while the 70-200 zoom is measured at f/2.8. When the 85/1.2 is measured at f/2.8 it will be considerably sharper than at f/1.2! – Michael C Mar 2 '18 at 1:22
  • People (who know what they are doing) buy the 85/1.2 for the curved field of focus that it provides. Typically, lenses with a curved field of focus show diminishing resolution near the edges when measured using flat test charts. But no one in their right mind would by a lens with a curved field of focus if their goal is to shoot pristine flat test charts. Or landscapes. – Michael C Mar 2 '18 at 1:25
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The achilles heel of decades old lenses, compared to current ones, is often in the coatings - you might need to be more careful with situations that can cause flare, both of the "ghost creating" type and the "global contrast reducing" type. Lenses made for film usage sometimes have much less attention paid to dealing with light reflected back into the rear element (as from a sensor)...

Use lens hoods where they do help; if adapted to APS-C digital bodies using a tighter (narrower/longer) lens hood might be advisable, just not so tight that you actually create an external aperture (occasionally, advice suggesting lens hoods that have a smaller opening than the front element diameter can be found. Often describing improvements in IQ similar to stopping down the lens. Guess what....). Mind that lens hoods help nothing if the flare source is right in the frame...

In case corner sharpness is unsatisfactory at the apertures you prefer to use, consider going for a composition that does not put in-focus things in the corners - or if most of the subject is in focus all across the frame, try to take advantage of the corner softness/lower corner contrast to highlight your center subject.

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