Pentacon Six/Kiew 6C lenses on a adapter

Sweet spot refers to the middle portion of the lens which is forming the image on the smaller target. The outer part of the image circle which normally exhibits the falloff of resolution and light, is cropped out. This alone is not ample reason to invest in medium format optics, but remains an advantage nonetheless.

As to multiplication factor: A 75mm is a 75mm no matter what format is used. All that changes is FOV. There's no multiplication issue to deal with. A 75mm lens for medium format, when used on a 35mm camera for example, has the same magnification as a 75mm lens designed for 35mm used on a 35mm camera.

Know what I mean?
 
I've read that lenses for medium format and large format cameras are actually less sharp than their 35mm bretheren, this being because the images they create don't have to be enlarged as much to get a large print size.

By zooming into academy ratio on a MF format lens you lose what seems to be the main draw of medium format photography: the hugh jass prints you can make. If you test the MTF of a 35mm lens vs. a medium format lens with both cropped to an academy size image area then my bet is that the 35mm lens will be sharper.

Now if the ground glass itself were Medium format sized, then things would be different. In terms of cost though, I can still see the definite advantages.

davide
 
IanD said:
Sweet spot refers to the middle portion of the lens which is forming the image on the smaller target. The outer part of the image circle which normally exhibits the falloff of resolution and light, is cropped out.
Click to expand...

I think I said that already.

IanD said:
As to multiplication factor: A 75mm is a 75mm no matter what format is used. All that changes is FOV. There's no multiplication issue to deal with. A 75mm lens for medium format, when used on a 35mm camera for example, has the same magnification as a 75mm lens designed for 35mm used on a 35mm camera.

Know what I mean?
Click to expand...

I do now. I just checked with 2 lenses of the same focal length designed for different film formats. So the only difference then is the distance needed from the back of the lens to the film plane to achieve focus and the size of the image circle.
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