I was thinking of using an ASI220mm with my Celestron OAG & C14 SCT with a Starizona V4 SCT corrector. The focal length is roughly 2300mm with this setup. In the past, I used to use a Lumicon giant easy guider and a Meade DSI pro II as the guide camera, and it worked fine. It uses the Sony ICX429ALL, and seemed to be plenty sensitive enough. It's comparable in size with the sensor that the ASI220mm uses, but the sensitivity with the ASI220mm is a lot higher than the ICX429ALL, so I would think that it would work fine. I can't use the DSI pro II anymore because I can't get in close enough to reach focus. I'm anticipating that this will not be a problem with the ASI220mm since the I can get the sensor closer to the prism. The alternative camera would the the ASI174mm which will have a larger field of view, but is not as sensitive. Would it still be advisable to use the ASI174,, vs the ASI220mm with this setup?
