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Last updated: 20 February 2012

Sent:	Saturday, February 18, 2012 15:31:53
From:	Mark Stewart (
Here is a finder/guide scope mod for the ETX80 and some results. Hope
someone finds them useful.

I have taken a Celestron finder and modified it for use as a guide
scope. The camera I am using for guiding is the meade DSI pro. The
camera would not come to focus as the tube was too long. I removed the
rear "eyepiece" by unscrewing it. I also unscrewed the front objective
and removed it. With just the tube I cut off the tube with a hacksaw
just behind the  indentation for the adjustment screws. I too a 2" to
1.25" eyepiece adapter and sanded the 2" barrel circumference down
just a bit so it would be a tight press fit into the tube. I took the
original cross hair eyepiece from the finder and glued it into a 3/4"
copper coupler. The coupler is just under 1.25", so it will still work
as an eyepiece for the finder. The front helical focuser still works
but I have it "locked" at focus for the guide camera and leave the
eyepieces out a bit ine the back for focus for them. I mainly use it
as a guide scope and having to worry with focusing the cameras is

It worked so well I made a 2nd one. I mounted it on my ETX80.
I placed my Mallincam (my main imager at the moment) in the eyepiece
holder. I placed the DSI pro in the guide scope which was already
mounted in the holder. I racked the focus of the scope all the way in
so the ota was as short as it would go. I placed the finder mount on
top placing it as close to the front part of the ota and not touching
it as I could. I drilled holes in bracket and ran screws through the
bracket into the ota (sorry my little ETX but it was for your own
good).  I also mounted a laser on top of the finder bracket but it is
used only to help align, and it is invaluable in helping getting close
to polar aligned.

Here are some pics of the finder/guide scope mod;

Here are some results of using the guider with the ETX80, hopefully
the will improve as I experiment with the PHD settings and the scope,
Some pictures of the ETX80 setup are here also;


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Copyright © 2012 Michael L. Weasner /
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