Celestron C80ED Refractor

I needed wide field scope for visual use with C9.25, C14, Obsession 18" and for autoguiding, and this one is very good for both purposes. Originally I mounted it piggybacked on C9.25 first using Ken Millburn's dovetail and rings, after buying CGE1400 I just bought a new dovetail. In both cases I had to add one more counterweight, otherwise I wasn't able to balance the OTA. When I got Obsession 18" I mounted it on the upper cage to use as wide field scope and finderscope. It is a very nice scope for wide-field visual observing, I usually orient eyepieces in such a way that I can quickly switch between the main scope and C80. 

Autoguiding works very well with C80ED, I use Meade DSI, Lodestar or Orion StarShoot Autoguider as autoguiding camera and PHD as guiding software. I added Orion Motofocus for easy remote focusing for autoguiding - they sell one for their own 80ED refractor, but it fits C80ED well. It is very important to mount C80ED as rigid as possible for autoguiding, and secure focusers and extensions to make them rigid too. For autoguiding I don't use a diagonal, but attach the guider camera with a 2" Orion eyepiece extender. Nevertheless, I found autoguiding with piggybacked C80ED good for exposures up to 5 minutes at focal ratios below f7 (f6.3 Celestron reducer on C14 OTA). For longer exposures inevitably some flexure shows up - and then it is time for an off-axis guider ...