P3D "Cheap" new lenses VS. "Quality" new lenses

[John Slivon <frogs@xxxxxxxxxx>]

I have been catching up on my list reading and see that a thread that is of
interest to me has almost vanished. I'll toss in my two cents worth anyway.

Quality camera lenses are designed to correct for many more distortions and
abberations than are simple lenses, even achromats. 

The Rikenon P&S lenses that I put into my Realist are matched as far as I
can tell, are sharp, have excellent contrast and good coverage. Their actual
focal length is about 33mm and they cover a 32mm wide frame at f/3.5 (wide
open). I use them mostly at f/8 and the fastest shutter speed for the
available light so that I can minimize any blur caused by camera movement. I
checked them with tech pan film developed for low contrast and checked the
resultant negative with a 5X loop. Maybe I got lucky! I think that the
modern computer designed and made Japanese P&S lenses are very good,
however, you can't get them into a Realist without a ton of work. If I had
good drawings of the Rikenon 3.5 lens conversion I would send them out to
all that were interested. However, all I have are rough sketches that helped
in the machining processes but are confusing to me now. The lenses I used
are 4 elements in 3 groups all ahead of the iris/shutter. Some of the later
P&S lenses are of similar design with an added negative meniscus lens behind
the iris/shutter. 
See (http://www.opconassociates.com/OpticsHandbook/bookframes.htm) bottom of
page 2 (wide angle) and continued on page 5.

I think that a simple achromat used at a small aperture would give good
results but over a small field and would be at its best as a  lens for macro
work.

An excellent book that addresses some of the problems of photographic lens
design is "Photography-Its materials and processes" by C.B. Neblette,
available occasionally in used book stores at a reasonable price. 

JS


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End of PHOTO-3D Digest 2737
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