Does this seem wrong?

Schneider's page
http://www.schneideroptics.com/info/...5,5-360mm.html

Schneider says "Recommended for 35mm". Strange. Isn't this the same lens
found on 4x5?

"jjs" wrote in message
...
Schneider's page
http://www.schneideroptics.com/info/...5,5-360mm.html

Schneider says "Recommended for 35mm". Strange. Isn't
this the same lens found on 4x5?

It isn't. The name is generic for a design _type_ rather
than a specific lens. The difference in a telephoto lens of
the same focal length for different formats is the coverage
and probably the telephoto ratio. The telephoto ratio is the
ratio of the back focus compared to a "normal" lens of the
same focal length. A 360mm lens is about 8 times the normal
focal length for a 35mm camera but only about 2.4 times the
normal FL for a 4x5 camera. Given the focus extension
available for the two the 35mm version needs to have a
considerably larger telephoto ratio. Also, any lens is
designed to cover a certain sized field. In general, the
larger the field the more difficult it is to correct the
lens to a given level of performance. For 35mm the field
angle of a 360mm lens is so limited that a relatively simple
lens will deliver good quality, for 4x5 the angle is much
larger so a different design is needed. But, since the image
maginification of a 4x5 negative will be much less the
criteria may be lower. In any case, while the generic type
may be the same, and the schematic drawings may look the
same, the lens is not the identical design just scaled for
the format.


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Richard Knoppow
Los Angeles, CA, USA