Sorry I never got back to you on Wednesday, Matt.. I was looking after the kids and didn't get time.
To elaborate on our PM conversation, I capture either RGB or LRGB. Like Bird, I haven't had fantastic results with LRGB every time, but it has worked at times.
RGB
I capture for 40 seconds in each channel. Allowing for 10 seconds between filter changes, the total capture time is approximately 2 minutes and 20 seconds.
Yes, at long focal lengths Jupiter has rotated in that time. But it just means aligning the colour channels on the
features, not on the limb.
If you align on the limb, the features in the middle will be less sharp because Jupiter has rotated. If you align on the features, it will mean moving green to the right 1 or 2 pixels, and blue to the right 2 or 3 pixels. You'll usually end up with a blue preceeding limb (on the right) but:
a) It can be reduced in processing
b) The features in the middle are aligned and sharp
c) It's worth it to get more frames for stacking.
You could capture for only 25 or 30 seconds each channel, but sometimes that extra 300 frames is worth it to be able to stack more for a smoother, less-noisy image.
Aligning the features rather than the limb is very difficult to do in AstraImage. What I do is do a rough alignment in AI (usually just align on the limb), and then in Photoshop I click on the "Channels" tab (bottom right pane) and by clicking each of the red, green, blue channels, you can see the features and how far they are off alignment. Focus on something like a white oval or a red barge, and click through each channel, using the "move tool" to shift the channel in the right direction - until the features are aligned when you click between them.
When you click on "RGB" to go back to the colour image, that's where you may see you've ended up with a blue right limb (I'm assuming you capture with South up).
This is different than capturing with a colour camera (DFK/ToUcam) for the same period. In that case you may end up with some rotational blurring beacuse all 3 channels are captured at the same time.
LRGB
Luminance imaging is hard to come to terms with until you've done it and seen what is meant by the luminance layer and the colour layer. Trust me, once you've done it once - it will become crystal clear.
When I've done LRGB imaging, it's usually because transparency has been bad (from dew or fog) and the individual colour channels are very dim, even at 15fps (1/15s). In this case, the luminance channel (no filter) is much brighter so you can capture at 30fps (1/30s) and get a full histogram.
The details on the planet come from the luminance capture. The colour channels are only captured to give THOSE details some colour. That's the hard part to understand until you assemble the image, so just go with me for now.
I capture luminance for 1 minute (30fps) and then the RGB channels for 20 seconds each (1/15 or 1/30, depending on transparency). That gives a total capture time of approx 2 minutes 30 seconds.
Yes, if you stacked all those and aligned on the limb, the blue channel would be shifted to the left by 2-4 pixels. But that's not the aim.
Stack all your data separately (L, R, G, B). The L channel is your details. You want this channel noise free, fine details, most time taken in processing. You'll end up with a monochrome image called your luminance channel.
Stack your R, G, B data separately - the processing doesn't have to be as much but make sure each of the RGB channels is processed the same so they end up with the same intensity, brightness, sharpness etc.
Combine the R,G,B channels into a colour image in AstraImage. This becomes your colour layer.
Now bring your luminance layer and your colour layer images into photoshop. Align your colour channels on a feature as explained above.
Select and copy your colour image (ctrl-A, ctrl-C) and paste it ontop of the luminance layer (ctrl-V). Now on the luminance image, you'll have 2 layers. The bottom monochrome image and the top colour image. For now, all you see is the colour image.
Use the "eye" toggle to switch on and off and colour image and the "move tool" to align your colour layer on top of the luminance layer so the features are lined up.
Now here's where you make an LRGB image.
While the colour layer is selected, in the blending mode dropdown select "Colour". This means the colour data is used to give colour to the luminance layer detail beneath.
If you're lucky, the end LRGB result is more detail and a smoother image, than a simple RGB image.
You can do normal post-processing from there, including levels, curves, saturation, noise-reduction etc.
I've had some success with LRGB images but some failures too, including bad onion rings around the edge. I'm not sure if it was the result of underexposure (not enough gamma) but to be on the safe side and ensure a quality result, I've just been doing simple RGB imaging and not capturing a luminance channel - especially when the seeing is good and you don't want to risk a bad result from a good night
Hope i've helped.
