Thanks Jim. You mentioned problems caused when using reducers and other accessories. What problems should I expect? Should I expect problems using Hyperstar?
I think you should be fine using the camera with Hyperstar since that scope design provides a nice big image at the focal plane. The problem is when you try to use focal reducers to achieve the same focal ratios you are used to with smaller sensors, like classical CCD video cameras. The diagonal dimension of the IMX294 is 21.6mm, that's almost 3 times larger than the 8mm sensors we were all using 5-6 years ago. Most of the telescopes and focal reducers people are using (the ones that we can afford anyway) are not able to provide a fully illuminated image plane as big as 21mm, and as a result you will get a large percentage of the sensor affected by coma and vignetting. With my ASI294 I limit myself to around 0.7 to 0.8x focal reduction (if any) as that is about as far as I can go before the coma and vignetting is too much. Care should also be given to your other accessories, for example you will want to use all 2" connectors, filters, nosepieces, etc. Again this is due to the size of the sensor.
Edited by jimthompson, 15 February 2019 - 02:25 PM.