Author Topic: 20mm or 25mm Plossl?  (Read 85 times)

afelfillia

  • Active Astronomer
  • ***
  • Posts: 141
  • Activity:
    0%
  • Reputation: +0/-0
    • View Profile
20mm or 25mm Plossl?
« on: December 24, 2017, 03:52:38 PM »
I want to replace my 26mm Celestron silver shirt Pl??ssl with something newer.  Taking a look at the TV 20mm Pl??ssl and the TV 25mm Pl??ssl, attempting to determine what would make one a better option than the other.
They're equally 1.25" 50 degree apparent eyepieces with 4 elements in 2 groups.
Eye relief to the 20mm is 14mm and for the 25mm it's 17mm.
Field stop for the 20mm is 17.1mm and for the 25mm it's 21.2mm.

My urge is to go with the 25mm only for the larger eye relief and larger field stop, but the 20mm would double the magnification of my 40mm Pl??ssl at which the 25mm wouldn't quite get there.

I'll admit I am a little fuzzy on the significance of the field stop, but figure if a person is good, more is better, right?

Which would you pick, and why?

Thanks!