[LargeFormat] Double Protar Lens

[Clive Warren]

At 17:31 04/09/2003 -0400, LNphoto wrote:
>A pair of 16 1/16" make for a 9 1/4" focal length that covers 6x8 wide 
>open and 8x10 at "smaller stops" usually f22
>
>I gotta check other sources on the lettered sets.
>
>the 16" Was part of the D set and in it's "normal" mount is probably the 
>same as the 18" cell.   The pair of 11" lenses are probably in a smaller 
>mount than the 16.
>
>So the 11" cells are US system.  That's unusual, at least here in the 
>States.   For the most part US system had been cast aside like a DAT tape 
>or a laser disc by WWI.  Maybe it hung on later over there.
>
>Les

Les,

Thanks for that - a bit longer combined FL than anticipated. Not too much 
in the way of movement on 8x10 then... at least it covers. It may end up 
being used on 5x7. Will keep my eyes open for the longest D set focal 
length cell.

The 11" cells are Bausch and Lomb so originate in the USA. From the 1958 
edition Focal Press Encyclopedia, The US system was proposed in 1881 by the 
Royal Photographic Society and was not much used in Britain or 'on the 
continent' <grin>  '......but it was used for some time in America, 
particularly on earlier Kodak cameras'. p.349 Vol. 1.

If we suppose that the lenses were made from 1895 (the patent date) then 
quite a few would have been made by 1914 as they were one of the best 
lenses available until around the early 1920's.

So it seems that we (UK) didn't always adopt new systems after you guys had 
already rejected them and moved onto something better :-)

Cheers,
            Clive