# Thread: First Post! - How Do I Measure My Bellows Extension To Calculate Bellows Exposure?

1. ## Re: First Post! - How Do I Measure My Bellows Extension To Calculate Bellows Exposure

Originally Posted by Pere Casals
Well, it's a biogon derivative...

At least here says "The lenses branded Super-Angulon (sold by Schneider Kreuznach and Leica Camera) are based on the construction of the Biogon."

https://en.wikipedia.org/wiki/Zeiss_Biogon

https://www.largeformatphotography.i...l=1#post817068
You trust wikipedia? ĦAy!

f/4.5 Biogons have 8 elements in 5 groups, aren't particularly symmetrical. f/8 SAs have 6 elements in 4 groups, are quite symmetrical. f/5.6 SAs have 8 elements in 4 groups, are also quite symmetrical.

2. ## Re: First Post! - How Do I Measure My Bellows Extension To Calculate Bellows Exposure

Originally Posted by Dan Fromm
You trust wikipedia? ĦAy!

f/4.5 Biogons have 8 elements in 5 groups, aren't particularly symmetrical. f/8 SAs have 6 elements in 4 groups, are quite symmetrical. f/5.6 SAs have 8 elements in 4 groups, are also quite symmetrical.
It would be interesting to know what makes a lens a biogon derivative, or even a biogon, because even the 1951 biogon is quite different from the 1934 original.

...but if the SAs and the Nikon SW 9 f/8 are not biogon derivatives then many people are wrong.

I guess... "The basic design principle is that you have a group with negative power at each end of the lens, surrounding one group with positive power on each side of the aperture. However you slice and dice or cement these groups is immaterial to the basic concept." (A.C.)

3. ## Re: First Post! - How Do I Measure My Bellows Extension To Calculate Bellows Exposure

Originally Posted by Pere Casals
...but if the SAs and the Nikon SW 9 f/8 are not biogon derivatives then many people are wrong.
There's a lot of that going around, alas.

4. ## Re: First Post! - How Do I Measure My Bellows Extension To Calculate Bellows Exposure

All I know is outcomes. Later Biogons in my typical applications work so very well in managing distortion and fall-off while SA lenses strive to be more and fail. I enjoy living within the later Biogon limits.

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