Re: Cooke Lenses (TECH-3D digest 1460

[T3D <bobh@xxxxxxxxxxxxxxxxxx>]

RE: PJ Homer was interested in my comments on RR and Cooke TRIPLET
and wants to hear more. Eric G. also commented which may also relate
to private email earlier.
First a lens label by NAME as Cooke (or more often, Taylor Hobson
Cooke, a renowned English firm) is not apt to be a Cooke Triplet at
all, but could be. As I told Eric (and sent picture of Technicolor
camera), THC invented the "retrofocus" design long before Angineau
out of necessity. They made the lenses for the Technicolor Corporation
cameras. Technicolor to most people's surprise was NOT a color film,
but a three color separation process to b&w neg with a movie version
of the one shot pellicle camera devised to shoot simulaneous three
color negs. The studios were under the thumb of TC because they
acquired their service which included camera(s), cameramen, color
Directors usually credited to Natlie Kalmus (wife of inventor) and
paid nothing for this, EXCEPT a royalty of so much a release foot of
film distributed, which added up to a lot of bucks. It took Eastman
color (and competitiors) a long time to become stable enough to
challenge Technicolor. But once it happened it was abandoned. Then
the studios could use there own equiptment and crews.
Peter's process lens could be a fine copy lens if labeled APO
(usually an Aviar design of four space elements, e.g. Kodak f/7.7
Ektar). Some modern lenses of this type of about 210mm f/4 or so with
diaphagm in cell are Xerox type copy machine lenses made by all
makers because of the huge demand. (e.g. Fuji). I have heard that the
early ones before color Xerox copiers were not suitable for general
photography as corrected for blue and UV the max sensitivity of the
selenium plate. Usually in Kingslake and Cox books is a list of trade
names that are classed as Cooke Triplets, Zeiss Tessars, Zeiss
Biotars (classic Gauss). The famed Zeiss Sonnar copied exactly in the
early Japanese f/1.5's is a Cooke triplet with each element multi-
compound. Prewar it scored as having better contrast because with
only three elements (allbeit cemented groups) it has least number of
reflective air-glass surfaces. e.g. six. Coating made the Gauss
design practical, and it prevailed. Interestingly, the original Leitz
Summicron of seven elements reverted to a standard gauss biotar type
because of manufacturing difficulties in making the original type.
As I may have mentioned earlier or told Eric...Leica change the famed
Elmar 90mm f/4 to a triplet and no one would buy it, so was
discontinued and is rare collectible now. They thought that with new
glass and computer design it was maybe as good and contrastier, but
that didn't cut it. Buyer decided it was the "cheap" version and
declined. (I am home one week from an operation, so have had to
arrange things so I can sit long enough to type these things). If I
had got my Voice Type going I could dictate Ha Ha!) BobH

------------------------------

End of TECH-3D Digest 147
*************************