75mm versus 90mm

[MEC]

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Hello. If I compared an image taken with my 75 summarit at f11/f16 with a slow shutter eg 1/125 or 1/90 with an image taken with my 90mm summicron APO with the same f stop and shutter, how similar would the images be aside from the 15mm difference? 
 

thanks in advance. 
 

Michael. 

[lct]

On what camera?

[MEC]

M10R. 

[lct]

Similar sharpness, vignetting, distortion and chromatic aberration, just a bit more DoF, at the same aperture, with the Summarit.

[MEC]

Would the colors render similar, too?

[lct]

To my eyes yes but colors are a subjective matter.

Edited March 20 by lct

[3D-Kraft.com]

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[luigi bertolotti]

14 hours ago, MEC said:

Hello. If I compared an image taken with my 75 summarit at f11/f16 with a slow shutter eg 1/125 or 1/90 with an image taken with my 90mm summicron APO with the same f stop and shutter, how similar would the images be aside from the 15mm difference? 
 

thanks in advance. 
 

Michael. 

I join Ict  opinion : I add that comparision can be more significant wide open or next to, (not at  infinity)

Edited March 21 by luigi bertolotti

[charlesphoto99]

19 hours ago, MEC said:

Hello. If I compared an image taken with my 75 summarit at f11/f16 with a slow shutter eg 1/125 or 1/90 with an image taken with my 90mm summicron APO with the same f stop and shutter, how similar would the images be aside from the 15mm difference? 
 

thanks in advance. 
 

Michael. 

At that aperture you would not be getting the best out of either of those lenses, so use only if that depth of field is needed. They should look almost identical otherwise, though the 90 APO may have just a bit more micro-contrast and pop. Also, since you say you have the lenses ('my') why don't you try and see for yourself? Lazy? Just realized that after wasting time answering your question. 

[MEC]

There’s usually a person or two or more on these forums with insight so it’s great to hear their perspective. Different lens designs etc may factor in. Like you’re saying the 90 may have more pop and micro contrast. Thanks. 

[Jeff S]

Take lots of pics using both, using different settings, subjects, distances, lighting conditions, editing practices, etc, then make prints using different settings, papers, profiles, lighting conditions, sizes, viewing distances, etc.  Then report back.  
 

No viewer knows, or cares, what gear was used for your pics/prints, other than maybe on a gear forum.  Years later, you probably won’t recall either.

[patrickcolpron]

21 hours ago, MEC said:

Hello. If I compared an image taken with my 75 summarit at f11/f16 with a slow shutter eg 1/125 or 1/90 with an image taken with my 90mm summicron APO with the same f stop and shutter, how similar would the images be aside from the 15mm difference? 
 

thanks in advance. 
 

Michael. 

Hi Michael,

Wrong test to compare these two lenses, a more honest comparaison would be at f/4 or f/5.6.  
 

I would never use either of those lenses at f/11 or f/16 oh ... the infamy of lens diffraction which starts at around f/9 on a 40 megapixel sensor, meaning you are getting less than optimal results starting at f11.
 

But at f/4 the rendering of an 90 APO will be very similar to a 75 Summarit, in terms of sharpness and color rendition on an M10R.
 

The DOF will be different meaning the fall off will be faster with a 90 at 1 meter with a close subject for a portrait but similar to one's eyes with a subject 5 meters away on a small screen.

There are two 75 Summarit, the 2.4 and 2.5 and I wouldn't trade either for a 90 APO. 

I barely use the 90, not worth keeping and the 75 sees the light of day more, but not by much. I use a 75 Summilux which is in my opinion a much more useable focal length on an M than a 90 will ever be. 
 

Hope this helps.

[MEC]

Thank you very much. I seldom use either lens but found myself at a car race and realized I found a use for them. I shoot wide open always but a couple of photographers there advised I use f11 or f16 and a slower shutter. So I did. That summarit is so much lighter. And that extra DOF and frame can make a difference especially from a fixed position. Thanks again. 

[laowai_]

On 3/20/2025 at 3:36 PM, MEC said:

Hello. If I compared an image taken with my 75 summarit at f11/f16 with a slow shutter eg 1/125 or 1/90 with an image taken with my 90mm summicron APO with the same f stop and shutter, how similar would the images be aside from the 15mm difference? 
 

thanks in advance. 
 

Michael. 

Michael, 

That's an interesting comparison. At f/11 and f/16, both your 75 mm Summarit and 90mm APO-Summicron are operating near their diffraction limits. This means the sharpness of the images will be primarily constrained by the physics of diffraction, rather than the specific optical design of the lenses themselves.

Aside from the obvious 15mm difference in focal length, and potential subtle differences in color rendering, the images will be remarkably similar. Factors like the shape of the aperture blades and minor manufacturing variations might introduce slight differences, but these would likely be very difficult to discern in a typical comparison.

[MEC]

I wasn't aware of lens diffraction. Thanks for explaining that. I always shoot wide open. I'm going to see if f8 is feasible in car photography. 

Thanks for your help. 

[lct]

On 3/22/2025 at 4:10 PM, MEC said:

I wasn't aware of lens diffraction [...]

Bit of diffraction at f/16 but none at f/11 on either lens, according to my copies at least.