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    What determines the field of view for the same magnification and objective lens?

    It's been an interesting discussion, thanks everyone for your comments.
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    What determines the field of view for the same magnification and objective lens?

    The aFOV is set by the field stop diameter and eyepiece focal length given by the equation: aFOV=2arctan(r/fe). Should' r ' read field stop radius rather than diameter?
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    What determines the field of view for the same magnification and objective lens?

    OK thanks, it's interesting that some older Porro designs like the Minolta range had a much wider fov than some modern roof prism types but of course they were heavier and less compact.
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    What determines the field of view for the same magnification and objective lens?

    Blimey, I knew someone with more knowledge would answer my question, that's very comprehensive reply. Thanks for taking the time and trouble answering in such a detailed way. Fascinating!! I have always had an interest in science and engineering so thanks for the relevant equations, PS you...
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    What determines the field of view for the same magnification and objective lens?

    Thanks TENEX I find this whole subject interesting.
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    What determines the field of view for the same magnification and objective lens?

    Thanks Binocollector, I had a lovely pair of Minolta 7x35 wide angle. They were very clear. I think I gave to a charity shop, wish I hadn't now but wanted to clear out some of my collection. Hopefully someone else is getting some use out of them now. I guess the popularity of roof prism...
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    What determines the field of view for the same magnification and objective lens?

    Thanks Mono that's interesting, I wasn't thinking about eyepieces having an effect
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    What determines the field of view for the same magnification and objective lens?

    I am puzzled. I thought all 8x42 would have identical fov but no!! Can anyone who has more knowledge tell me why the the field of view differs even though the magnification and objective lens are the same!! For example a friend of mine has a 10 year old Opticron 8x42 with only 6 degrees FOV...
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