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I noticed some bright green spots about the size of a star in my most recent image. The spots were in a cluster in a single area in the image. After looking at the subs, I saw a cluster of pixels that move around as I blinked through the registered subs (but only with the L and G filters on the 2600 MM camera). See attached photos. Wondering what this could be, or if I have a problem with the camera? I made a movie as I blinked through 228 subs at 0.05s. Thanks! HD.mp4   |
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The video is too compressed to show anything of value.
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Trying to stay under the limit. This is clearer. Video.mp4 |
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Well, All I can see it's a bright object jumping around in the FOV. Is it what you mean?
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Yes, It seems to be following the dithering pattern…changes every 2 sequential frames if viewed in order of capture.
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Whatever that is it should be rather straightforward to remove it from the stacked image, if that is what you want. As of the nature of it I'd have to see a single frame showing it.
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Are you dithering? The stars are steady in you movie, so that would mean it may be a fixed area on the sensor moving by dithering.
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I removed them. Just curious if anyone else has ever ran into this. Thanks.
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Yes, it follows the dithering pattern. It's not a single pixel, it's a group of about 20 that move together with the sensor. Maybe I have something wrong with the camera or a some kind of stacking artifact. I would have thought the rejection algorithms would have removed them as noise, since the location keeps switching relative to the other frames.
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Weird things can happen. Once I had an ant crawling on the sensor's window during a set of exposures and I couldn't figure out what was wrong with the stacked image until I saw its shadow.
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Perhaps ice crystals on your sensor - they typically congregate in the middle of the field in my experience and can be very persistent, even with anti-dew heater turned on. Were you operating in particularly humid conditions with a rapid camera cool-down?
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Jon Woodhead: That would also be my thinking. I had this recently myself and found it on my flats first, but later also discovered it on some of my light frames. Easy to get rid of, increase camera temperature by 15-20 °C, until they're gone and then very, very slowly cool down again. |
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Willem Jan Drijfhout:Jon Woodhead: Unfortunately they usually (in my experience) leave a residue behind which will continue to foul up images until it is cleaned. Usually it corrects out, but you can definitely see a mess in the flats when it happens. |
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Thanks All…appreciate the insight!
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Kyle Goodwin:Willem Jan Drijfhout:Jon Woodhead: That’s some good insight. I believe this time it all went away, but good point to check more specific. |
