The other disadvantage of the inverted mount is that an additional mirror may be needed when the sun is high. So many trade offs, and everyone makes them differently. That's why the world is interesting. From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Monday, September 26, 2011 1:59 PM Subject: Re: [Utah-astronomy] Gerrish mount To elaborate, Brent, the flat and it's yoke won't be a small assembly. I'm wary of cantilevering it at the top end of a long OTA for several reasons. Vibration is one concern, the other is that the only way I can aim this thing will be with digital setting circles. The DEC encoder will be on the flat yoke. Keeping it close to the ground will allow easy access if needed. I also don't want to have to lift that assembly up high since it won't be a lightweight. Also with the entire assembly using a short-focus scope, it can be made much more compact and easier to transport. An advantage to going with the mirror on top is that a diagonal would then need to be used in the focuser, making a total of 2 reflections and a left-right correct image, but still inverted. No big deal at all, since SCT users deal with left-right reversals all the time. But I'm sticking with the compact, original idea. My pockets aren't very deep these days. :o( _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php