Hello all, For well over a year now, I have been seeing dark horizontal bands showing up on some of my SBIG camera images, and to date, I have been unable to find a solution to this problem. From time to time during an imaging run, dark bands will appear in some of the downloaded lights, darks, bias, and flats images. I own several SBIG ST-series cameras, and this is happening with every camera not just one. I have updated USB drivers on my computer, tried various USB cables, and even tried using a USB to ethernet cable and this problem still exists. I have plugged the camera directly into the USB port on my computer and still see the bands. I am running The SkyX software on a Windows 10 Laptop using The SkyX camera plug-ins. I have also tried running the CCDSoft program on my Windows 10 computer and these bands still appear. During some imaging runs, this dark bands appear only a few times and then disappear for the rest of the night. Other nights they continue to appear in most images. I have a friend who is experiencing the same issues with his images and he is using his ST-2000XCM camera connected to a Windows XP computer. Not sure where to go from here so I am hoping someone on this forum has seen this problem with their camera and has a fix. Thank you in advance for your help! Clear Skies Jeff
Those old ST- cameras did not have a frame buffer; they could only store a couple of lines in memory. If the computer didn't keep up, then the readout would have to pause, and dark current continues to accumulate during those pauses. This resulted in a bright streak. If you're seeing dark bands, it's because your dark frames have light bands! The first thing to do is go over your dark frames, and throw out any that have light bands in them. That could also be confusing things, because you might fix the problem only to still have it sitting there in your dark library. Usually this is less of an issue with modern multithreaded computers, but if your camera readout is running on a thread that is being shared with other programs, it could get interrupted resulting in banding. In previous versions of Windows you could tinker with process priorities and thread assignments in the Task Manager. I don't think Windows 10 lets you do that anymore. In MaxIm DL we included code to raise the thread priority, but IIRC that is now disallowed also.
One more thing: The ST is a USB 1 device and it needs a dedicated (not shared) USB connection directly to the back of the computer. Make sure no other devices are on the same USB bus. In other words, no hubs or extenders, not routing through a hub in the telescope. There's a utility from Microsoft called USBView that can show you what devices roll up to which USB root hubs. You want the ST camera on it's own USB Root Hub, no other devices sharing it. Other USB devices can interrupt communication, and also devices at different speeds can cause issues as well (eg USB 3/2/1.1). So it's best to isolate the camera. Also, make sure your CPU isn't maxed out - it has to be fully available to get the data from the camera. So if you run a lot of programs, consider shutting down the unnecessary ones.
