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using a prism in a diagonal for a refractor

Started by BABOafrica, 01/25/2013 08:15AM
Posted 01/25/2013 08:15AM Opening Post
I decided to completely overhaul my 4" refractor.

Since I had an old binocular already missing some pieces, I decided to try to use on of the 4 prisms to make a better star diagonal. (I had been using a cheapie $8 piece purchased new on eBay three years ago.)

So I cobbled together something remotely resembling a diagonal using other spare parts from other objects.

I amazed at how well the prism performs for visual observation.

Not having much experience, I was wondering if it is quite common to use prisms in diagonals. Any comments?


In lumine tuo videbimus lumen.

8O Home-made 10” Dob / Home-made 4” refractor

EPs: Konig 32mm (1.25") / Zhumell WF 30mm (2") / Nagler 13mm T1 / Orion Sirius Plossls 25 & 10mm / Zhumell Plossl 9 mm / Meade MA 9mm
Posted 01/26/2013 03:21AM #1

Prism diagonals are commonly used in slower refractors with 1.25 inch focusers. Most of the classic refractors from the 1960's and 1970s used prism diagonals as do many SCTs. In faster telescopes a prism will result in some chromatic aberration.

For 2 inch focusers, they are quite uncommon.

What is the focal length of your 4 inch scope?