Posted by Don Spangler on January 13, 2001 at 10:31:48:
My fresnel lens has become scratched on the film
side. I have not been able to determine how this
happened but I believe that the C2 film adapter did
it. anyway does anyone know what to do. Just any
fresnel will not work since the focal plane must be
preserved. A fresnel not only alters the plane by its
thickness but also by its index of refraction. I have
been told about 1/3 of the thickness of the fresnel
can be expected. Any help on sources of fresnels
will be appreciated. I have tried Grimes and Stuart.