Jump to content

Walking on the Moon

2” eyepieces with a 66mm scope


Recommended Posts

If we assume the eyepiece has a 46.5mm field stop and the scope has a 303mm focal length, the TFOV = 46.5/303*57.2958 = 8.79 degrees.  The actual AFOV is irrelevant and highly dependent on various distortions.  It only affects the presentation of the TFOV to the eye.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

5 hours ago, Franklin said:

9 or 10 degrees? It all depends on whether the LVW 42 is taken as 72deg or 65deg. Mine is the older version and has 72deg printed on it but the more recent versions have 65deg?

Either way it's very wide and with a magnification of only 7x the exit pupil is 7.7mm, so it really needs a dark sky. There is some unavoidable curvature towards the outer of the field, but the views are stunning, nonetheless.

The field stop of the eyepiece was, per Vixen, 46.6mm.

The focal length of the scope is 300mm at f/5.45.  Exit pupil would be 7.7mm.

46.6/300 x 57.2958 = 8.9°

It doesn't matter what the apparent field is.  The limit is the inside diameter of the barrel, i.e. the field stop.

So that is the true field, not wider.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.