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Calculating the FOV of an eyepiece

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Is there an easy calculation to do this using scope f/l, eyepeiece fov and f/l??

What happens if you only have the f/l of eyepiece?

e.g C9.25 with 2350 f/l, ep fov 80°, f/l 11mm.

Would really help trying to determine what objects i'm seeing in my FOV and for calculating drift alignment accuracy.


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The AFOV (Apparent FOV) is the 800 - I suspect you just want FOV (i.e. the REAL field of view) ?

In which case its AFOV / Magnification (Magnification of course being focal length of scope over focal length of EP)


2350/11 = 213.6

80 / 213.6 = 0.375 degrees


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Welcome :D

I actually got the formula from the website that has the instructions on balancing a dual-mount that you posted elsewhere!! :D

Yeah, most plossls are 50/52 degrees.

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