[Leica] Biogon SWC (lack of) distortion

[benedenia at gmail.com (Marty Deveney)]

On Sun, Mar 4, 2012 at 9:42 PM, Richard Man <richard at richardmanphoto.com> 
wrote:
> OK, I have always thought that wideangle distortion is a fact of physics,
> Does the Biogon in the SWC actually has no such limitation?

The data on the lens are here:
http://www.hasselbladhistorical.eu/pdf/lds/CFi38.pdf  There is minimal
but not no distortion.

> e.g. circles appearing more oblong on the edges.

Optical design is a trade-off; the 38mm Biogon in the SW has very
little distortion but substantial vignetting that hardly improves
stopped down, a lot of field curvature and widely divergent tangential
and sagittal MTF.  The design only works in a slow lens and the
near-far performance isn't as good as a lens design with a floating
element.  This is what you 'gain' for losing the distortion and for a
lot of purposes the 40mm Distagon CF F/4 40MM (FLE) is a much better
lens, but it just depends on what you want.

The Leica 30mm and 35mm lenses for the S2 show that lens design has
moved on and that modern design, construction and glass really make a
huge difference in terms of technical capability.  The development
effort has not been just to bring out new lenses to sell.  These very
new lenses have downsides too, but lens design, like evolution, still
shows he effects of pressures which no longer exist.

Marty