Advantage of using a 2" diagonal

[Baron von Richthofen]

:shrug:Hi All
What is the advantage of using a 2" diagonal over a 1.25" diagonal in a 80mm F7.5 scope other than being able to use 2" eyepieces?

[Dennis]

In my experience with a William Optics 80ED F7 refractor, the 2” WO diagonal has a longer light path and allows me to come to focus with a WO 2” extension tube. If I insert my WO 1 ¼” diagonal, I need to use a 3” extension tube to reach focus, due to the shorter light path through the 1 ¼” diagonal.

Some WO ‘scopes, such as the 66mm F6 Petzval, are designed for a WO 2” diagonal with an SCT screw thread.

Cheers

Dennis

[marki]

Same with the Zenithstar 66. It has the SCT thread and Williams Optics recommend the 2 " diagonal. Only just got all the bits so will try it out tonight.