never failed getting a guide star. superb imaging for Jupiter and Saturn on my C8 SCT
At 2030mm I was able to find guide stars. I was in a hurry, so I didn't take the time tweak the settings. I did create a dark library, though. I only cranked the gain and binned 2x2 in PHD software. It got me through the night. The only issue was with the ZWO OAG, not the camera. The camera has a very wide FOV, but the prism on the OAG, not so much. With the ZWO OAG you get a small circle to locate your guide stars. But thanks to the sensitivity of the camera, you find guide stars easily.