Archived posting to the Leica Users Group, 2012/03/04

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Subject: [Leica] Biogon SWC (lack of) distortion
From: mark at rabinergroup.com (Mark Rabiner)
Date: Sun, 04 Mar 2012 07:37:14 -0500

because the 43 Biogon is a lens famous for having zero to no distortion. And
on a level that a retrofocal or non symmetric lens can't despite all the
well meaning computer design, high end glass and cutting edge coatings.

Hasselblad also used to put out very well designed square brochures which
were really like books. One on the superwide. Now we have search engines.
Bing or Google or whatever.  And you can shoot a grid and it will come out
with every square square just like it came in. Just make sure the camera is
level. As in real level perfectly level. In the last decade they came out
with a thing added on to the back which is like a groundglass with magnifier
to aid in this. They don't work on an old superwide as a Polaroid back wont
work.  As the levels on the camera can  be not quite enough.  And the
viewfinder tells you nothing.

I have just finished going over some very carefully made room views of my
old house in Portland which I shot level with a tripod with a pristine 21mm
Elmarit ASPH. A few perhaps with a 24mm Elmarit ASPH.
And as excellent as this glass is they are retrofocal not symmetrical.
I had to set it to 12 to get rid of barrel distortion in adobe camera ready
raw. That's a lot of cash to spend and not get much closer to perfection.

To this day I have never owned a true wide angle symmetrical lens.
And I am a big boy. As in old. And just a all around great guy..
But some day soon I can feel it in my bones.

A cool thing about them is they are quite low key. They mainly exist behind
the lens board. Most of them are in the camera not out. Like say the 21 SA
Super Angulon from Schneider which many have found to be the main reason to
get into Leica M for many decades. Not so great with digital I'm afraid.
I head there is a CS 21 which is a true wide angle and you can use it. Very
tiny. And proably very much better corrected than lenes costing very much
more.

A retrofocal lens I've read is like looking through a telescope backwards.
Bottom line a very crude way to design a wide angle lens.
But with a mirror to avoid and a metering path to avoid it was the only game
in town.

-- 
Mark R.
http://gallery.leica-users.org/v/lugalrabs/winterdays/


> From: Richard Man <richard at richardmanphoto.com>
> Reply-To: Leica Users Group <lug at leica-users.org>
> Date: Sun, 4 Mar 2012 04:04:01 -0800
> To: Leica Users Group <lug at leica-users.org>
> Subject: Re: [Leica] Biogon SWC (lack of) distortion
> 
> Yes, but my question is, how come the SWC Biogon doesn't seem to have the
> distortion of circles becoming oblong on the edges, or am I incorrect in
> saying that?
> 
> 
> 
> 
> -- 
> // richard <http://www.richardmanphoto.com>
> 
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information




Replies: Reply from roark.paul at gmail.com (Paul Roark) ([Leica] Biogon SWC (lack of) distortion)
In reply to: Message from richard at richardmanphoto.com (Richard Man) ([Leica] Biogon SWC (lack of) distortion)