Quote Originally Posted by Bob Denny View Post
One thing to try for diagnostic isolating problems is to turn on (checkmark visible) "Disable Slew During Image Download" (ACP Preferences, General tab). This uses a different (synchronous) read/download process in MaxIm.
Welcome back, Bob. I hope you enjoyed your family visit.

I now believe the camera is defective, and I am in email contact with an engineer at ZWO in China. He asked me to run a few tests, which I did yesterday.

MaxIm downloads images fine at ambient temperature, at 0C, and at -20C. The problem occurs after a 180-degree camera rotation at -20C (only). It does not occur after rotating with the sensor at 0C or ambient temperature -- only at -20C.

The mount is parked and powered-off, and ACP is not running -- just MaxIm alone.

After looping and tying-down all cables to the camera, there is no chance that rotating the camera puts any strain on any cable connected to the camera.

I suspect (and so does the ZWO engineer) that there could be a cold solder joint inside the camera. He wants me to do one more test using ZWO's ASICap imaging software, and tapping the camera when cooled to -20C vs. rotating it. I will do that tonight or tomorrow when the rain quits. I also will do this same test with MaxIm, since that's where the problem occurs, and is the program I must use with ACP.

Another part of the problem is that sometimes, when MaxIm does download an image, it is the previous image! Yesterday, I was imaging my light box when the problem occurred. I switched the light off and on during the 1-second exposures. After each exposure, MaxIm displayed "Reading" for 8 seconds, then downloaded the same light-on image every time. Very strange.

The camera has a 2-year warranty (bought new in July), and ZWO has been quite responsive. They even asked me where I bought it. Sounds like they're planning for an exchange.

Quote Originally Posted by Bob Denny View Post
...a different (synchronous) read/download process in MaxIm.
Is there a way to set this mode within MaxIm, independent of ACP? Might be worth a try.

--- Mike