Quote Originally Posted by bglick View Post
Nathan, nice post. From test results I have seen, and the lenses I have tested myself here is some findings..... high quality 35mm can have aerial resolutions at diffraction limited values.... the BEST MF lenses are very very close to diffraction limited, specifically Mamiya 7 lenses, (Mamiya achieved 350 lp/mm aerial resolution at f4)..... the best of the modern bunch of 4x5 lenses fall just a tad below the M7 lenses (specifically the 110, 150 SSXL), but there is others, most fall in the normal fl range....most of the older 4x5 or larger image circle lenses fall off up to about 30 - 40% of diffraction limited values... and older vintage LF lenses can fall down to 70% of diffraction limited values. Chris Perez's list of LF lens tests represent a bounty of data in this regard. Kudos to Chris for his contributions. Since MTF data is not available for many vintage lenses, Chris test results often are the best reference.
Does this imply that, all else being equal, the bigger the image circle of a lens the lower aerial resolution? I only ask because presumably a lens in front of 4x5 that would cover 10x8 would mean 2x the number of lines across the photograph than 4x5? This sort of implies that the best 4x5 lenses should have the smallest coverage which goes against my (admittedly simple) knowlege? Perhaps there is a tipping point around 10x8 that makes lenses a lot harder (or more expensive) to create...

Interesting thread...

Tim