Aluma AC4040/FW7-STX filter wheel with DL filters/Planewave CDK 17". Finally got images through this system. Luminance frames 600" binned 1x1. Color frames binned 2x2, 600". All High gain stackpro mode. The attached image shows an odd circular pattern in the center of M81. This is a red frame, G and B show a similar pattern. The L frames do not. I'm not sure what this is. The combined RGB frames are useless because of this pattern. Is a 2x2 600" exposure a bit much and this blown out? Is this a setting with high gain stackpro that needs to be changed? Transferring from a STL6303 CCD camera. Any input would be helpful. Thanks,
As always, please send a raw, unprocessed FITS frame showing the problem. We can't tell anything from a JPEG. Thanks!
As previously stated all of the color frames (RGB) have this oddity in the galaxy core. Another question...what is the suggested way to get proper RGB filter ratios? I know how to do it with a G2 star, is that the preferred method with the CMOS camera? Thank you,
The G2V star approach works fine. You can also use filter transmittivity and QE curve for the sensor, and adjust to taste.
Thanks Colin...did you have a chance to look at the image? There is a dark circular pattern in the center of the galaxy. Every one of the RGB frames has this but the L frames do not. I'm not sure if this is just blown out, or it could be something with high gain stack pro that needs to be set differently. If blown out, shorter exposures (these are 600", 2x2 binning) like maybe 300"? Asking as I'm not sure, this is a different camera than the 6303 was. Oh, you might recall that I was having difficulties getting flats with ACP. Set the ADU to 2100 and it worked. A few tweaks to make in ACP but I did get flats. Now if I can get color data.
Hi Mike, I suspect it's a StackPro artifact that was fixed in a later firmware/driver/software version. Which filter wheel do you have? AFW-10-50SQ or FW7-STX ? The reason I ask is normally I'd recommend upgrading firmware to the latest; however, we've had 2 reports of a problem with the FW7-STX filter wheels and the latest firmware. Resolving that issue is in Engineering's work queue right now. If you run DL Config Utility, what version of drivers and firmware does it report?
Thank you Colin. It is the FW7-STX filter wheel. Filter wheel-serial number SC1300m-20121701, firmware 6, usb handle: 0072eb48 This filter wheel just had the board replaced a couple of months ago. Driver 2.4.0.0 Maxim 6.28 So update the drivers and firmware for the camera and filter wheel, or is this going to cause problems with the filter wheel?
Whoops it looks like I sent the data for the guider, NOT the filter wheel...I'm guessing that the filter wheel has the latest firmware as it had the board replaced a couple of months ago...not sure how to see what it has in it as did not see in in the DLConfig utility... Camera serial: ac4040m-21012203 Firmware 13 USB handle-08d-80020
Filter wheel is non-upgradable and the DL Config 2.4.0.0 doesn't show it. Hold off on changes till I get a chance to connect with engineering.
Mike, did this only happen when you binned the image 2x2 during acquisition? In other words, does 1x1 image turn out fine?
Thank you Colin. To be clear, the image artifact is ONLY on the RGB frames. These are binned 2x2 and a 600" exposure. They ARE NOT on the L frames, binned 1x1 but also a 600" exposure. The L frames are very good data, the RGB frames about useless. This puzzles me, hence I started this thread. Didn't know if it was just blown out or there was some weird issue with camera or some such. And this is a CMOS chip, different than the STL6303E so I'm not sure what to make of it.
That doesn't make much sense to me. The camera doesn't know the difference between an RGB frame and a Luminance frame. It just relays the computer's commands to the filter wheel and otherwise ignore them. Are your exposure settings different for the L and RGB frames???
It's the binning, not the filters. StackPro is overflowing on high pixel counts during binning 2x2. I've logged a ticket for engineering. Basically the data is peaking above 65535 and wrapping, so as you get to the high intensity of the core, it starts counts at 0 again, giving the weird effect. We have to analyse this further.
The only thing that is different is the binning. The L frames are binned 1x1, the RGB frames are binned 2x2. For both, the exposure is 600". Could this be that the chip is saturated with 2x2 binning or something like that? All of the frames are high gain stackpro.
You can see what is going on in the attached image. View.. Graph Window reveals it nicely. The white line through the left to centre is what the graph is plotting.
OK thank you Colin. When the RGB frames are combined it is a pretty effect...but not quite what I am looking for. Would perhaps a short term solution be say a 300" exposure instead of a 600" when binned 2x2?
Okay you gave Colin enough of a clue to figure out part of it, and I've figured out the rest. It's a driver bug when you combine StackPro with Binning. If you do both at the same time you get this wraparound problem. My recommended solution: Do not bin your RGB frames. The first reason is of course the bug. We'll fix it at some point, but it isn't a high priority compared to some other things going on right now. The real reason it's not a high priority is... with a CMOS sensor there's absolutely no point binning your RGB frames! With a CCD sensor, when you bin the color frames you gain some SNR in the faint nebulous areas. It's a slight compromise to the overall resolution of the image, but because the Luminance frames are full resolution you don't lose that much. With a CMOS sensor, when you bin the color frames you get... nothing. The binning is digital. There's nothing to be gained by doing this. All that happens is you lose a little bit of image resolution. (For the record, certain CMOS sensors can bin 2x1... but most of them actually make the noise worse worse not better. The feature is there to support a higher frame rate, not to get higher quality. The 4040FSI can bin 2x1 but this makes the image worse. The 4040BSI can't bin at all.)
Hi Mike, Regarding the artifact, the DLAPI 2.7.1.0 API you just installed (over in the Filter Wheel discussion) will solve the issue.
For other owners of Aluma cameras, especially AC2020BSI, AC4040 and AC4040BSI cameras, we have an update for you. We released an update on Friday May 19 to the DL API Drivers. You can read about it and download here: https://forum.diffractionlimited.com/threads/dlapi-2-7-1-0-released.9722/
