Re: A thinner sensor stack may be possible after all!
edwardkaraa wrote:
Tariq Gibran wrote: edwardkaraa wrote:
It is no secret that the 35 biogon has a resolution drop in the extreme corners, but really the affected area is so tiny I would consider it negligible. I seem to have an excellent copy of the biogon, and it has even been finetuned at oberkochen, but I have to say, like with all traditional designs, it is very important at what distance to focus in order to maximize sharpness across the frame.
The MTF for the ZM from Zeiss only shows us the behavior stopped down to F4 where the corners even there look fairly respectable (they certainly don\'t take a dive into severe blurryland). I would have expected them to improve at 5.6 and certainly look great by F8. Frankly, in this instance, I don\'t think the poor extreme corners are due to the lens itself but rather the interaction with the lens and the M9 sensor (since those MTF\'s are based on film, not digital).
As far as I understand, the MTF bench is purely optical and does not use any recording medium, film or digital, but I could be wrong on that. Anyhow, my copy of the biogon behaves exactly as the MTF let you believe, and that is on both M9 and M240. The somewhat weak corners are there at wide apertures but go away by f/4. I don\'t exclude sample variations, or simply different RF calibrations.
The MTF\'s that Zeiss have given us most recently for the lenses that are specifically designed for digital (the Loxia\'s and the more recent ZM 35/1.4) are measured with the respective cover glass thickness taken into account (perhaps they place the glass in the optical path). I have not see them but apparently Zeiss even supplied Lloyd with two different MTF\'s for that ZM 35/1.4 - one for the Leica M digitals and one which showed how the lens performed on the Sony A7\'s. The older ZM\'s that predate the Leica digital M\'s, and were originally designed for the Zeiss Ikon and film- do not take into account any cover glass thickness so the measurements will not always apply (particularly for the wides of course) for how the lens will perform on digital sensors. That\'s my understanding anyway.
Feb 06, 2015 at 12:51 PM
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