[Leica] When a Biogon is no match for THE Biogon

[benedenia at gmail.com (Marty Deveney)]

Hi Tim,

> Does it have some retrofocus 'genes' as Zeiss says? ?Probably. ?But it if 
> it looks
> like a duck, quacks like a duck, and walks like a duck...

Symmetrical wides have very predictable single direction distortion,
while retrofocus lenses (and I call anything where the exit and
entrace pupils are different sizes as "retrofocus") have wavy or
"moustache" distortion.  All the Zeiss ZM wides and all the current
Leica wides have this moustache distortion, including the 21/4.5, and
the images don't look like those from symmetrical wides.

> I guess my point is that very few lenses stick with the pure designs of 
> the original Biogon, Planar, etc.

The names never really meant much, they're just names.

Marty