Optics Advice Please

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G Burt
Posts: 158
Joined: Sat May 02, 2009 2:37 pm

Optics Advice Please

Post by G Burt »

Hi All,

Could someone provide (or suggest a link to) a really straightforward layman's explanation about optics, including the relationship between focal length and field of view?

Thanks in Advance,

David Frydman
Posts: 5363
Joined: Mon Jan 18, 2010 9:25 am

Re: Optics Advice Please

Post by David Frydman »

Hi Geoff.
The AFOV, apparent FOV, depends only on the type of eyepiece.
45 to 50 deg Plossl
WA 60 to 65 deg, say Erfle type.
EWA 65 to 82 deg plus.

The real FOV is simply the AFOV divided by the magnification.

The magnification is the objective focal length divided by eyepiece fl.

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