[Leica] Don't Trust Everything You Read On The Internet, or: 2 Myths of the Biogon Lens

[richard at richardmanphoto.com (Richard Man)]

And a lens designer (his day job) named Jason spoke up:

>From a design point, the Biogon would be symmetric because the odd
aberrations in the first half are canceled by the odd aberrations in the
second half (odd aberrations including coma, distortion, and lateral
color). Kind of like a freebie. When this happens, we call the design
symmetric....even if the front and rear halves are physically slightly
different. It then becomes much easier to correct the remaining
aberrations. Hence why the fastest lenses are usually double gauss.

The physical difference in layout is because the lens is designed for
infinite conjugate..a fancy term for correction at infinite focus. But it
is still considered symmetrical due to negation of aberrations before and
after the central stop.

Contrast to something like a telephoto or Petzval, where the aberrations
are corrected individually in each group (Petzval), or just beat down by
lens shape, use of achromats, and other tricks in the bag (telephoto).


On Thu, Apr 23, 2015 at 9:34 PM, Bill Pearce <billcpearce at cox.net> wrote:

> My 50 for the blad is fantastic, my most used lens, but I must say the 250
> came in a close second. I'm just sorry I never got a superwide when I could
> have made money with it. They are sublime
>
> -----Original Message----- From: Mark Rabiner
> Sent: Thursday, April 23, 2015 10:21 PM
> To: Leica Users Group
> Subject: Re: [Leica] Don't Trust Everything You Read On The Internet, or:
> 2 Myths of the Biogon Lens
>
>
>
>
>
> On 4/23/15 5:44 PM, "George Lottermoser" <george.imagist at icloud.com>
> wrote:
>
>  And the 60s through 80s 'blad Zeiss glass, that I own, definitely always
>> pleases the eyes.
>>
>> Regards,
>> George Lottermoser
>>
>
> George the Hassy wides, 40 through 60 were as I'm sure you know retrofocal
> wides just like you'd find on any SLR or beam splitter unite camera its not
> symmetrical at all as there has to be nothing going backwards into the
> camera body very much getting in the way of stuff.
> But in the case of these Zeiss Distagon's made for a Hassy and also perhaps
> for Rollei and Alpa these were beyond the standards of the industry. They
> were the premium choice for medium format wide angle photography and roll
> film just like Leitz was for 35mm. If you used a medium format back on a
> view or technical camera perhaps you'd get to shoot with Schneider Super
> Angulon (SSA) and just typing those words out makes my heart skip a beat.
> The look the Zeiss Distagon's brought to the image is imbedded in our
> collective minds from all the commercial and magazine photography we'd ever
> seen especially before they got competition from the Japanese camera
> industry in the 80's with medium format Mamiya, Bronica and Pentax which
> undercut them by quite a bit on the price point.
>
>
> --
> Mark William Rabiner
> Photographer
> http://gallery.leica-users.org/v/lugalrabs/
>
>
>
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