When to Get a 2" ?

Greets,

When is getting a 2" eyepiece a must? What are the must have values? I'm thinking a 2" wouldn't make much difference in a 4.5" Newt, or am I wrong? Wouldn't they really be more appropriate for much larger scopes like maybe 12.5" or greater newts and larger refractors?

Matt

Well, it's never a "must", it's just if you're satisfied with the largest field of view you can get with 1.25" eyepieces. I'd love to have 2 inch capability for my 6" f8 newt. The biggest field of view I can get is about 1.4 degrees with 1.25 eyepieces; not really big enough for the Pleiades, for example. I can see the North America Nebula from good skies with a filter, but can only check out a portion of the "coastline" at a time.

Large fields of view are necessary for large objects (how about the Hyades?), make finding things easier, and are inherently beautiful - sweeping a 4 degree field of view through the Milky Way with a 4 inch refractor is one of my more memorable observing experiences from last summer.

The "need" for two inch eyepieces definitely gets more intense with big scopes and long focal lengths. But if you desire a 3 degree field of view, than any scope much over about 500mm focal length will need 2 inch capability; if you want at least a 2 degree field of view, any scope much over about 800mm focal length will need 2 inch capability.