why 2 inch over 1.25?

[Guest singelspeedman]

might be a basic question but as I have an imaging rig that only sees an ep for making sure everything is aligned after transport and the old scope is on the way out the door I have been thinking it might also be time to start getting better ep's for the visual side of things. The new 250px will take 1.25 and 2 inch. I have been happy with the 1.25 celestron plossl lenses for the last year but before I upgrade these I need to decide if 2 inch is the way to go - they must be more expensive for a reason other than size.

[Daz Type-R]

Bigger size lets in more light, simple as that!

[BAZ]

A 2" eyepiece is normally available for focal lengths of around 20 mm and over. They have larger lenses, so permit more light to pass through them and afford a good wide field of view. They are superb for the faint fuzzy side of things, and people have there own favorite sizes and brands.

If you get chance, have a look through a 28mm UWAN (Ultra Wide Angle), they have a 100 degree field of view, or a Televue, they will show you whats possible in eyepiece design.

My favorite is just a basic 26mm wide angle, it suits both me and my scope, as it's not too heavy. A 28mm UWAN is a whole kilo in weight, it's a great eyepiece, but I had to fight the scope to get it balanced right, and this changes as you move the scope up or down.

Anything below 20mm is 1.25", so you have a bit of a head start with your eyepiece set, and these are better than the supplied stock eyepieces.

Have a chat with this lot, I know a few of their members and they are also a friendly and helpful lot.

http://www.southcoastastro.co.uk/

[Guest singelspeedman]

thanks

[Doc]

The 28mm UWAN is 82° FOV so are all the TV Naglers. These retail for about £250. The Ethos range of TV's are 100° FOV along with the Edmund Scientific range of eyepieces. The TV 3.7mm is an astonishing 110° FOV.

Basically if they are 82° and over they let in much more light and have a much wider field of view, but they are much heavier then normal ep's and will need to have your scope balanced.

[Guest Tweedledum]

Hi Phil,

The view using 2" v 1.25" on a wide angle eyepiece is amazing, and echo comments above.

You are fortunate in that the mak has a high f ratio. This makes it more forgiving against a faster scope lower f ratio scope. You will get great results from less expensive 2" eyepieces. Get a good 2" diagonal and have a look for Moonfish, GSO or Bresser ep's. You can pick these up reasonably (c£50 used) and give you a great start to your 2" kit.

After this you need to take into account your stops within the scope and whether the rear port allows the full transmission for the 2" ep's. Also the exit diameter of the ep will usually be greater than the diameter of your pupil (6mm or so) so you have to get used to looking around the ep instead of just plonking your eye against your current ep's. Once started down this path you won't look back!!!

Cheers

Damian