[LargeFormat] Double Protar Lens

[Clive Warren]

At 7:20 pm -0400 1/9/03, LNphoto wrote:
Huge Snip
>According to my 1911 catalog, a pair of 11 3/16" cells give a 
>combinded focal lenght of 6 3/8" @ f6.3 and covers 4 1/2 x 7 1/4. 
>Something tells me in later years that was rounded to 5x7.    The 11 
>3/16" cell alone will cover 6x8 (whole plate) and has a back focus 
>of 12 7/16".
>
>I have a couple of B&L double protars....enough to make a D set.  I 
>also have C+ set from Zeiss.   While the glass may be similar, you 
>have to remember these were made with "native" machines.... The 
>Zeiss is metric through and through,  The B&L is Yankee.  The Ross 
>may be "stricken" with Whitworth threads, so that tube may need 
>different threads at one end than the other.
>
>Les

Les and Richard,

I seem to have become the target of used Protar dealers ;-)

There is now another set winging its way towards sunny Bristol from 
the caves of Mordor in the North.  This time it is again a set of 
same focal length cells, Bausch & Lomb - Zeiss Protar Series VII 
Focus 16 1/8" both front and rear cells.

 From what you have said, it seems that one of these would have formed 
part of a D set? Presumably in a larger diameter barrel than the C 
set. Perhaps your catalog has the info. for the combined focal 
length..... would be great if the combined lens covers 8x10 however I 
have the feeling that you are going to tell me that the combined FL 
is around 8".

It seems almost certain that the previous lens is a pair of 11 3/16" 
cells as you suggested. The stops are marked in the Unified System 
which caused me some confusion initially f:16 = f/16 and work from 
there......

Cheers,
        Clive