
Your first two eyepieces: what focal length and exit pupil actually mean
The two most useful eyepieces you can own probably aren’t the two that came in the box, and choosing them takes two numbers, not brand loyalty. Your telescope most likely arrived with a 25mm and a 10mm eyepiece. This piece is about what those millimetres actually do, why the 10mm is so uncomfortable to look through, and which two eyepieces to add first so you cover the sky from wide star fields to the cloud belts on Jupiter. No “best eyepiece” ranking. Just the arithmetic, worked on the scopes beginners actually buy. ...





