LF versus smaller format optics, which is better pixel for pixel?

[chris jordan]

Hi guys, question for the optical experts here. I have wondered for awhile now what is the finest resolution that can be obtained photographically, per square inch of sensor/film. Imagine this test: you shoot an image with 3 cameras all side by side: an 8x10 with a 200mm lens (with a high resolution digital back mounted behind it), a medium format with 200mm lens, and a 35mm DSLR with 200mm lens. All three rigs are the best quality, highest-resolution available, and all the photos are taken with the same aperture, shutter speed, lighting, etc. Then you crop all three images down to the size of the 35mm frame. Which of them would show the finest detail? I have always thought that the optics get worse the bigger you go format-wise, but a friend suggested that good quality LF lenses may out-resolve the smaller formats pixel for pixel. Thoughts?

[dmeckert]

I'm interested to see where this goes. I've always operated on the same premise you have.

[Mark Woods]

For an empirical test, shoot a standard cinema lens chart and look at the film with a microscope. I've seen cinema lenses (standard 35mm) resolve to 200 lines/mm. I don't really care about resolution so much as the "personality" of the lens. I use to use a lot of diffusion when I was working as a cinematographer -- with my Ziess lenses.

[Armin Seeholzer]

35mm lens will win this test, the GF lens wins if you use the whole 8x10 format and you enlarge the 35mm to 8x10!

Cheers Armin

[mdarnton]

Check these numbers:
http://www.hevanet.com/cperez/testing.html
Then remember that 35mm lenses regularly clock in MUCH higher. But as Armin said, your test isn't really how one would use a camera, with different film sizes and the same FL lens, and at the same field of view from the same place. . . .

[Eric Leppanen]

Have you see these tests?

https://www.onlandscape.co.uk/2011/1...ra-comparison/
https://www.onlandscape.co.uk/2011/1...ison-comments/
https://www.onlandscape.co.uk/2011/1...rs-commentary/

[Nodda Duma]

If you keep the focal length the same, the smaller the image plane the higher the resolution possible. There's no contest...it's not even a fair comparison.



Now, a fairer comparison would be to compare setups with the same field of view (say, 50mm focal length for 35mm format and the medium/large format equivalents), same lens designs, etc.

What you'll find is that everything scales, including aberrations. So your absolute spot size (blur size) is smallest for 35mm format, and it still beats out the larger sizes in absolute resolution.

*However* -- and this is important -- if you take your different sized negatives and make prints all of the same size (ie all 8x10s), you will find that their image quality is all equivalent: the minimum resolvable detail will all be the same size for all the prints. You've basically reversed the scaling of the geometric spot sizes for the larger formats.

This is what optical design theory states and what experience has shown me.

[ic-racer]

What "high resolution 8x10 back" is part of your test?

[fishbulb]

To me, this is one of those theoretical questions that doesn't really matter in practice. The more practical question to ask is 'how much resolution do I need for this, and what formats will deliver it?'. From there, other practical questions of size, weight, cost, ease of use, etc. are far more important than theoretical resolving power.

For what its worth though, my money would be on an ultramodern 35mm optic like the Zeiss Otus 85mm f/1.4 at about f/4.

[Jac@stafford.net]

[...] *However* -- and this is important -- if you take your different sized negatives and make prints all of the same size (ie all 8x10s), you will find that their image quality is all equivalent: the minimum resolvable detail will all be the same size for all the prints. You've basically reversed the scaling of the geometric spot sizes for the larger formats.

Emphasis is mine.

Resolution might be equivalent, but 'quality'? Quality includes tonal rendition. In that case, the miniature 35mm would be stressed and have lower tonal quality. No?
.