Originally posted by Ben_Edict Firstly, I think, all thread contributors acknowledged, that the particular lens, Jewelltrail tested against the 35mm lenses performed on the same level, resolution-wise. So I cannot see a general misconception.
okay, maybe i was a bit too vocal about it
. i was talking about my general experience regarding discussions on the subject, not about this thread. actually, the reason i engage in such discussions at all here is that i notice there are people who have insight and _think_, which makes it very interesting and gives us all a chance to learn and have a broader view.
Originally posted by Ben_Edict Secondly: The advantage of larger film formats is not about higher resolution as such. It never was and you won't find that as being a decisive advantage in the literature as well. The decisive point of using larger film formats is about tonality and finer tonal differentation! This is, why you can recognize a quality difference between a print made from 35mm and 4x5 inch. This is basically the same difference you get between a APS-C DSLR and a medium format DSLR.
that is a very interesting point, definetly worth noting. my mistake in giving the impression larger formats are _all_ about resolution/fine detail. another point often mentioned is the color "resolution" (which is closely connected to finer gradation you mentioned above), is that still meaningful with digital sensors though (does size still matter, if you have the same senzor? i think it does, indirectly, at least, because of dynamic range; any thoughts on that?)
Originally posted by Ben_Edict The highest resolution large format lenses achieve today, are defined by the Schneider-Kreuznach Apo Digitar series, as these are optimized for digital backs. Even these reach a resolution (offcially published by Schneider-Kreuznach) of a "mere" 60 lp/mm!
Going back to Jewelltrail's test. He used Pentax lenses, which seem to be acknowledged to be leading in terms of sharpness, contrast and resolution. I have none (except the old 500/4.5, which was available with 35mm or 67 mount and is not a good example in terms of contrast...), so I cannot validate that from my own experience. Photographers trying Mamiya lenses on the DSLR are generally disappointed (though this varies with the particualr lens used), as I read from several forum threads in dedicated pro forums. I will try that myself, if I find the time, as I have a nice collection of Mamiya glass, just need an adapter for K-mount.
interesting point again, however in my case it is a biometar (which is pretty much the cheapest mf lens you can find around, for the cheapest mf system (arguably) that ever existed: pentacon six.
my initial tests indicate very decent performance with the k20d (14mp sensor, so quite dense). it is hard to decide, because these were not scientific tests, but shot in the real world, and it's hard to be sure critical focus was achieved, and so on. i was not unhappy with the results though (not blown away eyther, as i noted)
Originally posted by Ben_Edict So, I stand by my initial response, that in general lenses made for MF and LF sport a lower resolution/resolving power, than dedicated 35mm lenses. This is emphasized by the generally agreed circle of (least) confusion, which for 35mm is 0.025mm, whereas for 5x7 inch it is 0.145mm (nearly 6 times bigger in diameter) - and all intermediate formats lying within that range.
Any way, we are discussing in this thread the general rule compared to particular practical experience. This is helpful and we can all derive new ideas from that. But single experiences do not devalidate a general rule.
Ben
correct, practical experience is different (but important imho). let me clarify what i was trying to say: not that the theory is wrong and we should ignore it, but that theory might not be always correct/complete, and that practical experimentation is worth it; at the end of the day, what you get from the lens is more important than what the numbers say, if you like the results and it delivers something you can't get easily otherwise, i think it is not important anymore if the numbers are "bad" in general (and, as you mentioned, might not be that bad for the particular lens). and i do agree that i would hardly buy a mf lens specifically for use on aps-c/35mm, unless i had a very specific need not covered otherwise (example: i bought recently a 300mm/4, again pentacon six system origin, it is big and heavy, but considered one of the best tele lenses one can buy, optically, and the price tends to be ridiculous. i cannot understate how big it is for a "mere" 300mm, though
)
sorry for the confusion. i will try to find time for more careful tests with the humble biometar, and maybe also post some 100% crops and such.
thanks for the insight