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1.25" EP in a 2" Diagonal

Started by astroboy314, 12/14/2002 01:26PM
Posted 12/14/2002 01:26PM Opening Post
Hello, I want to buy a new diagonal for my 8" SCT and want a 2" diagonal. I have all 1.25" EP's right now, though, so I was curious if the views through a 1.25" EP were restricted at all by using them in a 2" diagonal rather than a 1.25". Does it make a difference? If not I'll definately gop the 2" route. Thanks.
Posted 12/15/2002 07:29PM #1
To my mind you are better off getting a diagonal for a 2" focuser, so that it can also be used in any other refractor that you may buy in future. When you get the adapter that attaches the unthreaded diagonal to the SCT, you can always achieve focus. Unfortunately, this is not always the case when you try do the reverse, and try getting a threaded diagonal and adapter to work in a refractor.

Other problems with 2" diagonals,
a. The light path to the eyepiece is longer, so you will get somewhat higher power from all your eyepieces than you do now.
b. You have to be quick changing any eyepieces, else moisture or dust will easily make their way through mirror diagonals into the tube.
c. It's easier to turn thumbscrews that hold small diagonals in place, than turning the threaded ring which secures a threaded diagonal to its visual back.

I only really use mine when I want to see the views that my 30mm Widescan delivers through my C8, else I prefer sticking to my 1.25" diagonals (I have a TeleVue, Apogee mirror, Celestron prism, and a couple of 90 degree erect image ones).