Notice that it's placed in front of the objective focal plane and does not move with the eyepiece elements, so I think it should be considered a third objective element. My guess is that it's designed to correct field curvature by making the field curvatures of the objective and the eyepiece nearly complimentary. I agree with Ron that other so called "field flatteners" (Fujinon FMT-SX, Nikon SE, Pentax PIF) appear to correct astigmatism, but not field curvature.
Previous
Index
Next
Flat
Re: Nagler-like performance...
Edit
Reply
Quote
