freaklikeme wrote:
On the 43 and 77, I\'m guessing it\'s just Pentax being honest, instead of labeling them 45 and 80, like everyone else would\'ve done.
58 has a longer and more varied history. I can think of three companies, Zeiss, Nikon, and Minolta, who produced lenses at this focal length. No idea why they did it, but I\'m glad they did.
I always though Nikon\'s 105mm was weird. Had the goal been to make a 100 and they just couldn\'t shave off that last 5mm?
My understanding is that it\'s easier to design a fast 57-58mm lens than a 50mm lens of the same aperture.
There was also the Hexanon AR 57/1.2.
I recall theSuede explaining why in a thread a couple of years ago.
[Edit] Here\'s his explanation:
The >57mm <60mm lens on an SLR-type camera has a very specific meaning. It\'s very much easier to construct a 57mm+ lens with the back-focal distance needed due to the mirror-box than it is to do the same with a 50mm lens. If you want to do a 50mm lens with the classical ultron/planar layout you have to \"compress\" the back end to make it fit, and that effects performance by a noticeable amount.
Some new base constructions have surfaced in the last few years, that makes shorter, fast lenses available for a lot less money.
Not sure how this applies to fast 55\'s like the Canon FD 55/1.2, the Contax C/Y 55/1.2, and the Yashica ML 55/1.2 though...
