What fits a 1.25-inch focuser
The 1.25-inch barrel fits almost any telescope, and here it covers five Explore Scientific series: the 52°, 62°, 68°, 72° ED and 82°, from 3 mm to 30 mm. Five filters take the same fitting: an ND 0.9 for the Moon's glare, a CLS light-pollution filter, and H-alpha and S-II narrowband filters for imaging.
Choosing an eyepiece
Focal length
Magnification is the telescope's focal length divided by the eyepiece's. Short focal lengths give the high power the Moon and planets need, and long ones the low power and wide views for star clusters and nebulae, up to a useful limit of about 2x per millimeter of aperture.
Apparent field
True field is about the apparent field divided by the magnification, so at the same power an 82° shows about 1.6 times the width of sky of a 52°. The wider series weigh and cost more.
Eye relief
If you observe with glasses, choose 15 mm or more. Every 52° and 1.25-inch 72° ED model here gives it, and so do the long eye relief 82° models.
When to go 2-inch
A 1.25-inch barrel's field stop tops out at about 27 mm, so the widest low-power views need a 2-inch eyepiece and focuser.
Frequently Asked Questions
Which focal lengths should I start with?
One each for low, medium and high power. A 2x focal extender then doubles the set.
Will these fit my telescope?
Any telescope with a 1.25-inch focuser or diagonal, which is nearly all of them.
What does the ND filter do?
The ND 0.9 cuts the Moon's brightness, for a more comfortable view in which fine detail is easier to see.
For the widest views, browse our 2-inch eyepieces, and for building a set, read Best Telescope Eyepieces: A Buyer's Guide.