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| p.5 #9 · Metabones Speed Booster |
That "whitepaper" contains a bit to much PR buzzwords to be taken seriously, but the theory behind the concept is good.
Two things remain to be verified:
1) does it really perform at F2.0 or F1.4? They've only shown small samples and 20lp/mm figures - and mainly from videographers (who I guess is the main target group anyway)
2) how good is the flexibility between lenses with different exit pupil distances/sizes? Will it be equally good with a 50/1.4 as with a 135/2.0?
one is already halfway answered in the white-paper, a 50mm F1.8 AIS lens will get about 2/3 Ev more vignetting and worse corners than the no-adapter FF version. More than good enough for hipstamatics and videographers, maybe less impressive if you've ever seen the lens used on a D600.
Given that I know who designed it, the lp/mm comparison as a concept is laughable. They should (and do) know better, so I guess they had very little to do with the actual "white-paper".
Yes, the 20lp/mm contrast goes up (in the center part of the frame at least...) - but that's totally irrelevant. To compare a lens used on FF with a lens/converter combo used at µFT the µFT combo needs to have the same MTF at 40lp/mm as the FF combo does at 20lp/mm - if you want the end result, the finished image, to be as sharp. 20lp/mm is a line 4 pixels wide on a 20+MP FF camera, and a line about 7 pixels wide on a 16MP µFT. There's quite a lot of difference between a 4-pixel blur and a 7-pixel blur.
For videographers, this is a godsend. For photographers, less so. You could compare the full-size images from a FF-camera with a certain lens with the full-size image from an APS-NEX with the same lens and this converter, and the result is quite easily predictable - the APS image will be noticeably worse. The questions is just "by how much?". In physics, there's no such thing as a free lunch - Newtons law of thermodynamics and so on. You can only increase the losses of a black-box system (a lens), never lower them.
The object-side resolution of the lens will be worse, the adapter will cost a lot of money, the AF will be slow or non-existing, the camera system as a whole will lose a lot of the "compact" appeal. It had better be very, very close to a zero loss system for the practical aspects to ever outweigh just getting a FF-based system in the first place.