Last night, when I brought up my rig after being covered for bad weather I had a couple of nasty surprises. First my hard drive for data is dead. My mounted fanless PC has two hard drives and the main drive is OK, but I could not get the data drive to come up. That was annoying but I worked around it. The second issue is more of a problem.
I noticed that the intensity level of my images was lower than I expected. I normally start taking short exposures and watch the counts until the background comes down as it get dark. But the counts were too low. I was able to reach temperature just fine. I could take images just fine. they were just too dim. Its like the gain was off. So I tried going back to the ASCOM driver instead of the ZWO native driver and the give the same results. I rebooted my computer and re set up with the same results. I looked down the OTA and saw no evidence of frosting and the images showed no evidence of fogging. they looked perfectly normal, just dim. I tried changing gain settings from 76 to 200 and the intensity responded but still lower counts. I moved to my heart nebula target and took 300s Ha subs and compared then to the previous session and again they looked just dim. It was late and I saw no evidence that this was dew or fogging so I just let the data collect.
After work while still daylight, I looked again down the OTA to check and I could clearly see the sensor and the optics looked fine with not fogging or dew. So I set up my flats and LED panel. I compared flats intensities with my standard setup and instead of 31000 ADU I was getting 28500 ADU with the same settings. I am at a loss here to explain this, but it is an issue. I removed the camera and opened it to check the desiccant tablet. They looked fine and so did the sensor. I microwaved my desiccant tablets and re-installed them. I saw no film or any clear moisture on the sensor while it was open. I reinstalled the camera and retook flat with no change. Still about the same lower intensity.
I simply looks like the gain setting is off and I am not getting the gain expected for the setting in the software. I have tried multiple computes, USB3 cables and both the native and ASCOM drivers with no change. I can talk to the camera, get data from the camera with out issue. The images are just like they have a lower gain setting. I verified that both drivers are set at 16bits also. The dark frames are also off from my library for this camera - also like the gain is wrong. I have no problem cooling the camera.
I have an ASI1600MM-COOL on my SCT that I can move over and test also, but I think at this point I would like some outside input on what could be the issue.
