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?
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 while 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...
I like 43mm as it is true normal FL for 35mm; 40mm always looks very linear and in-between; then there are Leica R zooms of 105-280mm and 70-180, CYs 35-135...58mm feels good, 60 macros seem weird. Maybe it's just me.
58mm and really 55mm (which note Zeiss are now repopularising) flatten features a little from 50mm, more of a short portrait FL these days, can have better focus fade and bokeh maybe - nice.
RustyBug wrote:
What other odd focal length lenses are there ... and why?
My favorite example is the Elmar-V 65/3.5 for the Visoflex system. 65mm was the shortest FL of non-retrofocal design that could clear the moving mirror.
Leitz Visoflex - For the man who has everything (except an SLR).
Nikons 43-86mm zoom is one of those focal length choices I never understood. It refuses to be a wide angle on the one end and just doesn´t make it to enough tele on the other end to justify the hassle of owning a zoom lens.
freaklikeme wrote:
On the 43 and 77, I'm guessing it's just Pentax being honest
Honest? I don't know of any lenses that are that far from their nominal focal length, so I think Pentax just wanted to offer something different (still close to popular FLs).
cputeq wrote:
Your post assumes 50mm, 35mm and 85mm are not odd themselves
50mm, or rather 51mm which is apparently the actual focal length of many 50mm lenses, is so ciose to 2 inches that it makes me wonder whether that was how it started. Note that Germany did not metricate until after Zeiss was already in business. (I know, but Wikipedia only lists it as a country in their metrication article. Goethe's Italian Journey in the original German gives distances in miles...) Japan did not metricate until 1957, just two years before the Nikon F, and Shimano bike parts were stlll imperial into the 1980s.
85mm is 3 1/3 inches.
35mm is slighly less than 1 1/2 inches (38mm).
My contribution for odd focal length is the Olympus OM Zuiko 65-200mm f/4, when everyone else was making 70-210.
When I said 4:3 I meant a 1.33X magnification FL @ 4:3 x 3:2 = 4:2 (i.e. 2X), maybe some portrait vs. landscape orientation rationale ... not intended @ different format discussion.
