I received a STF 8300M on Dec 22. The past few nights are the first chance to use it (in Seattle area). It replaces a ST 8300M that I have had since they first came out. My problem is that all of my images, bias, darks, & lights have a minimum pixel value of 1000. If enough light hits the image, it registers fine but nothing below 1K ADU. I have included (with historgrams) a bias, a light at 60 sec where the image is just coming past the 1K threshold and a light at 55 sec where the 1K limit still dominates Am I missing something or is this a service call. Thanks, Steve Ruhl
According to this post it is normal and not a problem. http://forum.diffractionlimited.com/threads/st-8-bias-level.2933/#post-15717 William.
1000 ADU offset is normal; however, I want to make sure it's not clipped for some reason. Please post a FITS bias frame image (or short exposure dark frame).
Probably not relevant but I notice in your uploaded bias images - fits headers - that cooling was off, temp reported was +7 deg, when Doug evaluated the image for clipping etc should the CCD be cooled?
Hi William, When I shoot images, I turn the cooling on. Hypothetically, for bias it should not matter since you are not measuring dark current in that short of duration. If I was using the bias for calibration, I would because I shoot darks at the same time. Thanks, Steve
In general it's better to provide thermally regulated images, but in this instance that won't change my conclusion at all. Your camera was manufactured in July 2016. Test data looks normal, QA records indicate no problems. Are you running it with the AC power supply that came with the camera?
Recommend you ditch that power supply - some have very poor regulation and high ripple. You might be lucky with a good one, but doubt it.
Hi Doug, Based on your question, I took a bias with the original PS and it appeared to have good characteristics. So I ripped apart my wiring and reworked the connections. And now it works. I must have had a cold solder joint that broke while replacing the st 8300 for the stf 8300. Thanks Doug. BTW, I have had the PS for about 10 years and have never had a problem. Thanks All, Steve
