Posted by Bob Stoddard on March 12, 2001 at 14:58:26:
In Reply to: Re: Old Rollfilm Lenses on Century 2x3 posted by Bill Morgan on March 11, 2001 at 19:15:18:A useful rule of thumb for calculating the covering power of
4-element Tessar-type lenses is to remember that they often will
generate an image circle which is about 1.25 times the focal length
of the lens, when they are stopped down.
Thus an 80mm Tessar-type could be expected to give reasonable
coverage of a 100mm image circle, and would be easily able to cover
6 X 7 cm. and just barely able to cover 6 X 9.
But you have to expect variations from lens to lens, so testing
would be important. RKS