JM> I used Rob's excel spreadsheet to calculate lpmm for three lenses at JM> available apertures f2-f8: the M85/2, FA 100/2.8 Macro, and a manual JM> focus Vivitar VS1 28-105/2.8-4 (fairly new cheap lens, not some old JM> cult classic).
John, you said we can flame away as we like ;-) So take on your azbesthos suit: lpm doesn't say much about any lens quality. It doesn't take into account resolution at different contrast levels, nor does it much see coma. Nor does it sees different gradations each lens has. With the high contrast resolution targets, often even cheap zooms will perform well, but get into low contrast targets, and the lens resolves only a muddy mush. You would have to have at least resolution targets with several widely different contrast ratios. Either some difficult MTF tests, which are pretty difficult to do meaningully as well (as always, chosing the right distance, chosing full daylight spectrum, etc...something they don't do at Photodo), or real world scenes... You certainly did good at chosing the right distance for portraits, and your test does tell something about the lenses, and the digital sensor is different enough that some great lenses can perform badly on it, but still, you only tested for high contrast resolution. So your test is useful, but it doesn't tell the whole picture :) I am personally not in favour of lens testing. It's very hard to evaluate properly, not subjectively, and the results are equally hard to project into one's photographic needs. Best regards, Frantisek Vlcek
