|
A 40mm eyepiece will give you an exit pupil of 5mm, which is about as much light as you can get into your eye, unless you are under 50! The 30mm wont give much different to your existing 25mm, so if I were you I would look at a 40mm.
The other thing you might want to think about is the field of view of the eyepiece: plossl eyepieces generally have around 50 degree apparent field: so you would about 1.6 degrees true field with a 40mm plossl (about 3x the width of the moon). Some of the more expensive eyepieces have 68, 80, even 100 degrees apparent field of view, so you can get up to 2x the true field for the same magnification, depending on the eyepiece.
It all depends on what you want to look at, and how deep is your pocket!
- Dean
|