[LargeFormat] Fun with Convertible Lenses
Jay Allen
largeformat@f32.net
Sun Dec 30 11:35:15 2001
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Fun with Convertible Lenses:
How can a modern large format lens be any fun? You can not even take it
apart to use it!
Convertible "symmetrical" lenses offer multi-focal lengths to the large
format photographer.
I the early days the lens designers found that if they used similar
shaped glass on both sides of the diaphragm that it solved a lot of
optical problems. So the invented the symmetrical lens.
A popular primitive one was the "Rapid Rectilinear lens".
Later mores sophisticated lenses came out like:
The Dagor and Turner-Reich
These later lenses are made up of 8 and 10 elements with clear cement
holding two multi-element lenses together. They do not require lens
coating because the designers removed the air-spaces between the
elements.
These lenses were the top work-horses for the large-format commercial
photographer during the first half of the twentieth century. And still
provide beautiful work.
And, as a bonus, they are convertible. That is,they were offered in 2 or
3 focal lengths. When the front and back elements are used separately on
the shutter.
Do you know what a "Casket Set" is?
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Jay Allen
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or go to: escape.to/jays
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