Originally posted by ElJamoquio You've said larger sensors do not necessarily have a resolution advantage under all circumstances. For which circumstances does APS-C have better resolution than FF?
The differences between APS-C and FF are smaller than you think, to put it into perspective a DX format sensor has 28.28mm* diagonal vs FF having a 42.27mm Diagonal I see a bigger difference between FF and 645 which has a 70mm diagonal. Even with both images printed at 8X10 I can spot a difference between 35mm and 645 - but at that print size I can't tell a difference between 645 and 67.
Originally posted by ElJamoquio Lenses have a resolution that can be measured.
Of course they do, but these days we rely on digital sensors to measure it and the sensors have finite resolution - not to mention many cameras that have AA filters which has an impact on lens performance as well. But I have yet to see any digital sensor that clearly out resolves a well designed lens when used below the diffraction limit. Speaking of which the diffraction limit is more of a problem on FF sensors - because you have to stop down more. An extreme example of this would be when I need to use my 8X10 view camera - to get more or less the whole landscape in focus I have to stop down to f/64** without using tilt or shift - though with tilt and shift I can often get away with using f/22 which by coincidence happens to be the optimal aperture for a majority of large format lenses.
IMHO if there is a difference between FF and APS-C It is so trivial I really couldn't bring myself to care about it. You can count Photons all you want ElJamoquio, I'll be out taking pictures.
*There seems to be some disagreement on the actual dimensions of a "standard" DX sensor, some sources say 15.8mm X 22.3mm - but here i'm using Kodak's DX standard as 15.69mm X 23.53mm
**some of the older long lenses I have for 8X10 have f/ stops as high as f/192 - or as people who value truth above all else: hello and goodbye resolution.