Thought some of you might be interested in this comparison between the MTFs of three 21mm Zeiss Biogons, the Elmarit ASPH, and the new Leica Super-Elmar. Leica and Zeiss MTFs may be acquired under different conditions, so the comparisons between brands may not be entirely fair. (Is Leica using computed or measured MTFs these days?)
In all cases lines for 10, 20, 40 cyc are shown. Leica's specification for 5 cyc is
not shown. Kind of pointless for lenses at this level, anyway.
Rangefinder 21mm lenses: the State of the Art by
Semilog, on Flickr
And distortion (the Elmarit ASPH and SE are pretty much the same so only the SE is shown):
21Distortion by
Semilog, on Flickr
Take-homes:
• As many others have noted, the G Biogon 21/2.8 is a GREAT lens, small light sharp fast and almost no distortion. Too bad I love my M6 so much :-/. FWIW I'm currently shooting the 21/2.8 Biogon.
• The slow lenses (Biogon-C and S-E) don't improve in any meaningful way when stopped down. They give you more DoF and less vignetting. That's it.
• Zeiss cares more about correcting for distortion than Leica does.
• Zeiss really did match or exceed the 21 Elmarit ASPH with the 21/2.8 ZM — at a third the price, the same weight and bulk, and a better filter thread size. Bravo.
• On film it doesn't really matter which of these lenses you use, unless even a small amount of distortion is problematic. By f/5.6 they are all pretty much the same.
• If you shoot an M9 you
really want the S-E due to the position of its rear nodal point. Accept no substitutes.
• Every one of these lenses stomps the Summilux ASPH. Big, heavy, blocks even the ZM accessory finder, distorts like a pig, absurdly expensive, not as sharp as any of the alternatives, and why would you need an ultra-fast 21 anyway? The S-E is everything that the 'lux is not.