[LargeFormat] Double Protar Lens

[Richard Knoppow]

----- Original Message ----- 
From: "Clive Warren" <cocam@blueyonder.co.uk>
To: <largeformat@f32.net>
Sent: Thursday, September 04, 2003 12:39 PM
Subject: Re: [LargeFormat] Double Protar Lens


> 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
>