Re: [Leica] 21 or 24 mm M lens: advice sought

[Mark Rabiner <mrabiner@concentric.net>]

Dennis Painter wrote:
> 
> Mark Rabiner wrote:
> >
> <snip>
> > In rereading Erwin's pages on the 21s he does not specifically address
> > the distortion issue with the ASPH as he does with the other 21's as a
> > word "distortion". He says all aspects of the lens are vastly better. He
> > says: "Astigmatism and curvature of field are almost fully corrected"
> > which are distortion issues I should think.
> 
> Astigmatism and curvature of field are not distortion.  Think of
> astigmatism error as a failure to correctly image a single point in the
> subject as a single point on the film.
> 
> Curvature of field is failing to bring all points of a flat surface into
> flat focus at the film plane. The focus field at the film plane is
> curved, hence the name.
> 
> The 21 SA and 21 ASPH are both great performers. The SA having the
> disadvantage of not metering on the M6, the ASPG having the disadvantage
> of greater depletion of the bank account.  If you can afford it I would
> say get the ASPH.
> 
> Dennis
> 
> > But he doesn't specially say
> > better corrected than the SA. People should read this themselves to make
> > sure my comprehension agrees with theirs.
> > I had asked the tech rep at Leica if the new 21 or the SA were "true"
> > wide angle lenses like the Biogon and view camera lenses and thus
> > possessing their intrinsic lack of distortion which you describe here so
> > excellently. His answers were relational and I was confused and not
> > perhaps absorbing important points. Your present response clarifies some
> > of that now.
> <snip>
> > Mark Rabiner

Thanks for this needed correction. Mr. Wulff was discussing that from a
total distortion perspective coming from at least the needs of an
Architectural photographer, the SA has less distortion.  So I got the
impression that for his work the SA might be more useful despite most
other aspects of the lens being not up to par with the modern. This was
in reponse to my writing off the SA as archaic in reponse to my reading
Erwin's articles. As much as I love the whole ASPH thing the allure of
what I at least call a "true" wide angle lens is strong although rekindled.
I wonder if the ported over to Leica from Contact Biogon allows use of
meter and is non Retrofocus? I imagine not. Someone should come out with
one, I would snap it up for less than a G.
Mark Rabiner