Cameras and Lenses

Question about eye relief/FOV

It's my understanding that, generally speaking, eye relief and FOV are often inversely proportional. What is the affect, if any, roof vs porro design has on this?

[QUOTE=stubaldwin]It's my understanding that, generally speaking, eye relief and FOV are often inversely proportional. What is the affect, if any, roof vs porro design has on this?[/QUOTE]

"Often" is the operative word here--not "always." One example of the opposite effect is the notorious example of the ocular lenses used in the 7 x 42 roof prism binoculars in the 1980's in the Leitz Trinovid and the Zeiss Dialyt binoculars which gave both a very long ER and a very wide FOV. This seems to have been rather unique to the 7 x 42 format and did not extend to other formats like 8 x 42 or 8 x 32 where the ER got shorter when the FOV got wider.

It is my understanding that both ER and FOV are determined by the optical design of the ocular lens. I may be wrong, but I don't think the prism's used have much affect unless they change the effective focal length of the binocular by shortening or lengthening it. Maybe this is why some very wide 8 x porro's with oversize prism's like the Nikon 8 x 30 EII and Swift 8 .5 x 44 model 804 had short ER?

In any case, it is a subject that deserves some "enlightened" comment by our resident experts.

Cordially,
Bob

Thank you, Bob, for your response. I, too, would be very interested in hearing from our experts.
Stuart

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