do a bit of figuring with regard to the LP/mm and MTF achievable by cheap digicam lenses compared to the best 35mm and LF lenses and you'll find a pretty direct inverse correlation between image circle coverage and the LP/mm value where MTF falls below 50%.
I've done the figuring. That's why I'm able to make and understand statements that all lenses at equal physical aperture and equal FoV, regardless of format, will provide the same total image resolution (excluding degradation caused by film or sensor). That shorter focal length lenses with smaller image circles deliver higher spatial resolution (more lp/mm) is implicit in the above statement.
Were it not so, then 35mm at a diffraction limited f8 could not provide the same resolution as 8x10 at a diffraction limited f64. Absolute resolution at f8 has to be 8x as great as LF at f64. That's simple maths.
The point I'm making, which again seems to have escaped you, is that lp/mm at f4 with 35mm is not even nearly 8x as great as the equivalent 8x10 f32. Where's the problem in appreciating that fact? It seems quite clear to me, or are you perhaps refuting my claim that opening up from f64 on 8x10 format to f32 does not substantially increase resolution?
I admit there's not much reliable information available on the net regarding MTF tests of LF lenses, but following is an extract from a Schneider Optics FAQ on large format lenses. 7. Why does the sharpness of my lens increase as I stop down, and then decrease as I stop down further? You are experiencing the effects of two primary optical aberrations, spherical aberration and diffraction. As you stop the lens down, spherical aberration is reduced, and the effects of diffraction are increased. This generally results in a "sweet spot" around f11, where the image has benefited from reduced spherical aberration, but not yet been degraded severely by diffraction. At small apertures such as f64, diffraction effects are quite large and the image will be noticeably softer.
The interesting thing here is that Schneider Optics LF lenses have a sweet spot at f11. You'd almost think they were referring to 35mm. I assume it's the smaller LF lenses for 4x5 format they're referring to. Even so, a sweet spot at f11 on 4x5 format is equivalent to a 35mm lens with a sweet spot at f2.8.
The most thorough series of LF lens tests I can find on the net is by Perez and Talman. Their results can be viewed here
Again, it's not clear which of the tested lenses would be suitable for 8x10 format, but I think it's likely that some of the 360mm and longer would be. I checked out some of the names and it seems some photographers are using some of these lenses with 8x10 format, such as the Fuji C-Series F12.5 for which there are 2 sets of results in the table, the first of which shows best resolution (and equal resolution) from f12.5 to f22. At f32, diffraction is already taking its toll. That would be equivalent to a 35mm lens having a sweet spot at f stops ranging from f1.6 to f2.8 with a progressive deterioration in resolution at larger fstop numbers.
If larger is always better, why stop at 8x10? Why not 16x20, or 24x36, or something even larger?
Do you not remember a thread a while ago about an American who built his own very,very large format camera. He had the lens poking out of one side of a van, exposed something like a 4'x6' image on the other side of the van and made contact prints of apparently amazing resolution. He drove around visiting schools to demonstrate the principles of photography. Pretty stupid, eh?
I just came across some MTF details of a wide angle lens with an image circle of 500mm designed for a 9x18" format camera. Usable resolution is 30lp/mm. Such a lens used with a cropped 8x10 format would deliver 30 lp/mm even into the corners at no less than 30% MTF. With a crop factor of 5/3, the 210mm wide angle lens becomes pretty close to a standard lens for 8x10. To capture that resolution you'd need at least a 180mp Foveon type sensor or perhaps better a 300MB Bayer type since sensitivity is an issue. . Do you think there's a snowball's chance in he*ll of anyone designing a 35mm lens that can make use of 180 megapixels. We're only up to 16mp with the 1ds2 and already people are complaining their lenses are not good enough.
Your arguments seem to be flying in the face of the facts, Jonathan. Details of this lens can be found here