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Jezz, sorry, been so long since I ues my scope I haven't looked in this thread! There is software out there that aligns and stacks images. I use Registax. It doesn't deal well with field rotation, so it is best to do all your data from each channel in one night.
I've done colors on consecutive nights, and combining them into an RGB image works best if the camera remains attached to the scope during the few nights of imaging so there aren't any rotation issues.
For luminance, I just went two months between capturing the color data and replacing some poor luminance data with better luminance data using a hydrogen alpha filter. So nothing about the camera setup was the same - not even the magnification. But it was relatively easy to rotate and stretch the luminance image in Photoshop.
Here's the full saga:
On 6/20 I shot:
14 exposures at 30 seconds for red (7 minutes)
27 exposures at 45 seconds for blue (20 minutes)
26 exposures at 45 seconds for green (20 minutes)
The red channel is more sensitive than the other two, so I use less exposure, though the number of exposures really should be equal. Also, tracking wasn't very good that night, so I had to discard a lot of frames. Still, the overall exposure time was a little on the low side. My first attached image is the resulting RGB.
I then shot:
34 exposures at 2 min for luminance (1:08 total) the same night.
Due to my bad tracking, the stars came out egg-shaped. So the second attached image is the combined lrgb. Not terrible, but the egg-shaped stars are a dealbraker to me. Plus the exposure time seemed a little low - the detail wasn't great.
Then I had two solid months of clouds, during whcih the telescope was set up in my living room. Last night was the first good night of sky(and perfect tracking) in months, and I shot:
26 exposures at 4 min each with a hydrogen alpha filter (1:44 total).
The third image is the result of combining that luminance image with the earlier color data. It's just under 2.5 hours of data altogether. I really could have used longer subs for the color, but it is good enough I'm not going to redo it for a long time. This was the first target I ever imaged (last year) and I've spent way too much time on it trying to get a good one as I climbed the learning curve. My first attempt is here, earlier in the thread (11 months ago): https://www.physicsforums.com/showpost.php?p=1097341&postcount=148
I've done colors on consecutive nights, and combining them into an RGB image works best if the camera remains attached to the scope during the few nights of imaging so there aren't any rotation issues.
For luminance, I just went two months between capturing the color data and replacing some poor luminance data with better luminance data using a hydrogen alpha filter. So nothing about the camera setup was the same - not even the magnification. But it was relatively easy to rotate and stretch the luminance image in Photoshop.
Here's the full saga:
On 6/20 I shot:
14 exposures at 30 seconds for red (7 minutes)
27 exposures at 45 seconds for blue (20 minutes)
26 exposures at 45 seconds for green (20 minutes)
The red channel is more sensitive than the other two, so I use less exposure, though the number of exposures really should be equal. Also, tracking wasn't very good that night, so I had to discard a lot of frames. Still, the overall exposure time was a little on the low side. My first attached image is the resulting RGB.
I then shot:
34 exposures at 2 min for luminance (1:08 total) the same night.
Due to my bad tracking, the stars came out egg-shaped. So the second attached image is the combined lrgb. Not terrible, but the egg-shaped stars are a dealbraker to me. Plus the exposure time seemed a little low - the detail wasn't great.
Then I had two solid months of clouds, during whcih the telescope was set up in my living room. Last night was the first good night of sky(and perfect tracking) in months, and I shot:
26 exposures at 4 min each with a hydrogen alpha filter (1:44 total).
The third image is the result of combining that luminance image with the earlier color data. It's just under 2.5 hours of data altogether. I really could have used longer subs for the color, but it is good enough I'm not going to redo it for a long time. This was the first target I ever imaged (last year) and I've spent way too much time on it trying to get a good one as I climbed the learning curve. My first attempt is here, earlier in the thread (11 months ago): https://www.physicsforums.com/showpost.php?p=1097341&postcount=148