The past few nights my STXL camera has been displaying an odd behavior. After taking a series of images that look normal (lots of stars) it suddenly takes an image with only a few barely visible stars. The two linked images below demonstrate the issue. These images were taken back-to-back without moving the telescope. Both images had the same exposure, 20 seconds. The cooler was set to -10°C and was running at 34%. There were no camera errors displayed. I can usually fix the problem by recycling the camera power, but that fix is only temporary. I’ve done excellent photometry with this camera for 10 years and I’m hoping this summer’s heat has not damaged it. Any suggestions on how to troubleshoot this problem would be most appreciated! Ed https://drive.google.com/file/d/1C-LBELQfHZLiPXw878E93GPtR5MyQEk5/view?usp=sharing https://drive.google.com/file/d/1X6qVbBZOtF42Jn05UKDot8bfaEXxT0jT/view?usp=sharing
I tried subtracting the two images... the dim one makes a pretty good dark frame for the bright one. This suggests that the camera took the correct duration of exposure, but not much light reached the sensor. Since they're back-to-back and on the same filter band, I think we can rule out the filter wheel. That would lead me to suspect the shutter. I'd suggest dismounting the camera, and then run a series of exposures while watching the shutter - see if it does anything strange.
Hi Doug- Thanks for the quick response. I removed the camera and opened it up to verify the belt was on correctly and then I used CCDOps5 rather than Maxim DL6 for making the test exposures (2 seconds). The first exposure looked perfect. The shutter rotated into position and took a 2s exposure then rotated to the opaque position. The second exposure failed and CCDOps5 displayed a shutter error. I was working mostly in the dark (red flashlight), but I think I observed the shutter rotate partway and then rotate the other way (is that even possible?). The 3rd exposure worked perfectly. The 4th exposure failed. I did this for about 20 exposures and the pattern was clear. Every other exposure failed with a shutter error. During subsequent failures I don't believe the shutter was moving. I then recycled the camera power and tried another series of exposures. The results were exactly the same, the first one worked then every other exposure failed with the shutter error. Not sure why Maxim wasn't generating an error in my last imaging session. The problem first cropped up a several days ago with only occasional failures which worsened on subsequent nights. In my last imaging session, the failures were not so regular. Once a failure occurred it may take several exposures before the shutter worked again giving a good image. Ed
Your camera may need service. Let us know if you need RMA instructions. One thing to check first - if you've swapped adapters on the front at some point, it's possible you have installed screws that are too long, and could be interfering with the shutter.
I had removed the FW8G-STXL Guider/Filter wheel before running the test exposures. I replaced the filter wheel with the original cover and its 8 perimeter hex screws. I took the cover off again just to verify that there was no possible way those screws could come in contact with the shutter. The threaded telescope/focuser adapter was also not attached so those four screws were not an issue. Go ahead and send me the RMA instructions. The CCD window also has a small defect (appears to be a fractured in the glass) that creates a dense set of donuts on images that flats do not fully correct. I could have the window replaced a well if I sent it in for repairs. Thanks for your help!
Hi Ed, Can you please submit the following RMA contact form? Then I can send you an RMA number and return instructions. http://diffractionlimited.com/request-rma
