Which diagonal, 1 1/4" or 2" ??

Other than giving up the ability to use my one and (so far) only 2" ep, what do I give up by choosing the 1 1/4" dielectric diagonal over the 2"? I intend to use the diagonal on a LOMO
5 1/4" MCT and on an Intes-Micro M703 7" MCT.
Kind regards,
Mike.

You would save a little now on the purchase, with the 2 inch you are leaving yourself more options however. The 2" can use both sizes of eyepieces therefor giving you more choices in eyepieces. If you are working on acquiring eyepieces but staying on a budget schedule, the 1.25" is not a bad way to go because with the extra money you save, you are already on your way to your next eyepiece.

Bill Burghardt said:

Other than possible back focus problems with short focal length eyepieces in some telescope, the positive note is that the 2 inch diagonal gives you room for diverity in selecting new eyepeices. Cost difference is not that big an issue on your purchase, UNLESS, you buy a 1-1/4 diagonal and next week get a great chance on that 2 inch eyepiece. NOW you need to go out and double your expenditure for diagonal for the 2 inch compatable diagonal.

Simple words, get it now, and need not buy it later.

Best wishes.

I would personally do this by considering true field of view. I believe that the 703 has a focal length of 1750 mm. Limited to 1.25" eyepieces this gives you a theoretical maximum field of view of just under .9 degrees (too narrow for me). With the 2 inch eyepieces you get a theoretical field of just over 1.5 degrees, which is reasonably comfortable for me. I like deep sky and extended objects, I also star hop, so I like a wider potential field than some folks.

Best of luck!
Lorne Johnson