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Riccardi x 75 Reducer

Sky-Watcher Equinox 100 Reducer
3 replies‱212 views
Christian Vulpescu avatar
Christian Vulpescu avatar
Hi guys, finaly I found out, was the backfocus extention for any given scope for the Riccardi x 0.75 reducer is:

The magic answer is: 22 mm!!!

So you add 22 mm to your initial back focus - e.g.: 55mm + 22 mm = 77 mm.

Clear Skies Bros

Christian 😃
Michael Lev avatar
Michael Lev avatar
The backfocus changes based on the telescope and which reducer size it is.
There is a sprite sheet somewhere on the internet with many scopes and the correct backfocus measurements.
Stjepan Prugovečki avatar
Stjepan Prugovečki avatar
55mm is not any kind of standard for reducers.  The backfocus of that particular reducer (and almost all others)  is telesope dependent 
and for Riccardi 0.75 it is not 55mm for any scope . The specs are from 70-80mm for , listed in https://www.apm-telescopes.net/downloads/manuals/Riccardi%20Reducer%20Info%20at%20May%202014%20(4).pdf for various scopes.
Christian Vulpescu avatar
Christian Vulpescu avatar
The plus of 20 mm backfocus is written in the manual of the Riccardi reducer.
A far as I know, in the combination with the Skywatcher Esprit 100 ED and an ASI cam it would be 75 mm backfokus.