Hello all, I'm a long time SBIG/DL user over the years. Previously CCDs, but now I'm fortunate to have a new AC4040 (with filter wheel, off-axis guider and AO-X) to set up and install at an observatory with a PlaneWave CDK24. It is a couple hours from me, and we operate it remotely, so I'd like to do some tests here at home to insure it is operating well before putting the AC4040 on the telescope. What would the group suggest? I'm new to CMOS, so perhaps I should take a series of bias and dark and light frames using different read out modes? "High" vs. "High StackPro"? I'm testing the cooling by running it a 0 and -10C a couple hours each day, and it appears to be working well. Thanks for your thoughts, and I look forward to the group's advice in the future as I work through processing/acquisition differences with CMOS. Best, Mark Manner Super old and out of date website: MBA (spotastro.com)
I've been testing, using a pinhole in an aluminum foil cover, and see a few persistent dark spots in the image. You can see 4 of them fairly clearly in the lighter part of the image. I'm using an autodark, camera temperature 0C. Attached is a 2x2 bin fit file. I've tried low and high readout, binned and unbinned, and the dark spots shown on the fit file attached are the same. Also appear if I do not do a dark subtraction. Thanks for your thoughts/comments. Best, Mark
A pinhole test is very sensitive to even the tiniest dust speck. Open the shutter and use some compressed air on the front chamber window.
Hi Doug, I tried compressed air, but they seem to be persistent. I can't really see them directly on the chamber window using a bright light. Attached is a bias frame in case that is of any help. It seems really good to me so not the sensor. If I increase the pinhole size (I was using a very small one), they become less visible, so perhaps very small dust on cover I can't see. I'm reluctant to try an alcohol cleaning at this point, since I suspect given my test that they will not be visible when on the telescope. Thanks for the help, Mark
Bias looks fine. All cameras have to pass a dust test during production; we have a specification that all cameras have to pass. We also carefully clean out the non-optical parts of the chamber, to mitigate the risk that a residual particle hiding somewhere in there could migrate onto the sensor after shipping. It is extremely rare for that to happen, as particles tend to adhere very strongly to surfaces. I'd suggest waiting to see how it works on the telescope. Pinholes tend to produce an extremely narrow beam of light, which makes the dust spot look much worse. An f/9 or f/5 telescope system is much less demanding.
