Re: RR Lenses (TECH-3D digest 144)

[T3D <bobh@xxxxxxxxxxxxxxxxxx>]

RE: Grant Campos is musing about Rapid Rectilinear lenses from a pair 
of Kodak folders for a stereo camera consturction. And wonders about 
separating elements from shutter etc.
First the RR lens was at one time the common amateur lens as it was 
balanced around the diaphragm so gave no distortion! I believe it is 
two achromats, but there might be  a paired meniscus version??
What you should know it that it is a lousy lens by present day 
standards as it is astigmatic and has to be limited to small f/stops, 
so rarely is faster than f/8..although the universal scale was in use 
then with setting numbers like 1, 2, 3, 4.
The RR was quickly dispaced after 1908 or thereabouts by the 
wonderful Cooke Triplet. While we look down on this lens today it is 
a marvel as it is an anastigmat, can be fast, can focus via front 
element, and is the simplest quality lens that can be made for 
photographic purposes thanks to Dennis Taylor of Taylor, Hobson, 
Cooke. While they deny it...all Tessars and similar lenses can be 
seen as Cooke triplets with a compound third element, in the Ross 
Xpress a 3 element third element instead of a pair as with Tessars.
While one works with what he has available, I would certainly be put 
off with a deficient design that has astigmastism, poor color, and is 
uncoated, compared to finding some more modern folders with good 
lenses that might be lying around. BobH


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End of TECH-3D Digest 145
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