But the Perez/Thalmann test results show resolution differences when using film at f/22, and my concern is that these differences would become magnified when using the Betterlight. For example, the two Fuji 240A samples tested consistently recorded resolutions of 60 lpmm or greater even at the edges, whereas the Nikkor 300M and Fuji 450C samples tested recorded resolutions no greater than 54 lpmm (and in one case as low as 34 lpmm). Since the 240A data proved that the test setup is capable of resolving at least 60 lpmm (actually one lens tested resolved as high as 85 lpmm), mustnít the lower resolutions recorded with the Nikkor and Fuji be solely due to limitations with these lenses? And if resolution is capped at 54 lpmm by lens design, how can a digital scanning back possibly record any greater resolution than that recorded with film?
One of the limitations of the Perez/Thalmann tests is that they were performed at a magnification ratio of 1:20, which for 4x5 equates to a focus distance of roughly 8 feet. Much of landscape photography is shot at or near infinity focus, which may be why Jack has experienced good results with his 300M and 450C (my understanding is that the Fuji C series are optimized for infinity, and this has certainly been my experience with my 450C and 600C lenses). But if one wants to shoot close-up with these lenses (as I frequently do), then my concern is that the scanning back would not provide any additional resolution over film. Similarly, I use my SS80XL for roughly 20% of my shots (frequently with lots of front rise), and here again, the concern would be that this lens gets relatively soft at the edges, and (like Jack's Super Angulon) would not provide any additional resolution versus film. To makes things worse, the Betterlight has a 1.25 focal length multiplier, so I'd have use a 65mm lens to get a similar angle of view to my 80mm, which almost certainly will be even softer (and have significantly less image circle). So add these resolution limitations to the challenges of slow scanning speeds and multiple tethered system components, and the Betterlight becomes an extremely specialized tool.
I agree that the digital scanning back could become more universally interesting if subjected to continuing technology development. I worked in the computer hardware industry for 20 years, and I see no reason why a scanning back could not eventually migrate into a far faster and more integrated solution (perhaps not completely unteathered, but laptop computers are getting so light and power efficient that this may not matter much). The question is does Betterlight have enough revenue to finance such continuing R&D? And will the market be big enough? I certainly hope so. But if more and more people find 30MP to be "good enough", then this certainly does not bode well for future scanning backs.
As for lens resolution with the P45, I'm glad to hear that the Hasselblad and Mamiya lenses held up well in the shootout test. Perhaps the resolution difference experienced by Michael Reichmann between his Contax and Rodenstock wide-angle lenses was just specific to that particular focal length (or limitations in the Contax), and should not be extrapolated to other focal lengths. Yet I keep hearing rumblings about Hasselblad and Schneider developing new lenses to better resolve digital sensors. Perhaps these rumblings are false, as with so many rumors. Hopefully we won't have to wait too much longer to find out!