Moon Imaging with ASI1600MM - need help

[turbo_pascale]

I tried to do some images last night of the moon with my 80ED @ 480mm.

I shot using SharpCap and did 3000 frames each of RGB.
I did a 1760x1760 region of interest.
The images were shot all within about 5 minutes or so.

I stacked each of the three of them in AutoStackkert3, and was relatively happy with the result, sharpened out of the box.

However, I can't quite get them to line up (manually in photoshop, or in Registax6). The Red channel is off by about half a pixel vertically at the bottom of the image (at the top it is ok).

I'm struggling a bit to work out the right way to do this, and stent too many hours already looking for the right workflow steps.

I'm thinking I need to go back and stack them with a 3x Drizzle to pump up the pixels, and then I may have a bit better chance of finding an alignment.

Unless someone can teach me how to move the channels around in partial pixel distances?

These are the times I wish I had bought a one shot colour as well!

Can anyone point me to some resources on how I might fix this?

[Camelopardalis]

I don't have an answer for you, Rob, but keen to hear of any potential solutions.

I did a similar thing the other night, only mine are way more than half a pixel around the poles :sadeyes:

[John K]

Registax 6 has an RGB align feature that you may want to try.

Can I ask why you are doing an RGB image of the moon rather than just B&W?

Also maybe download a trial version of PixInsight which has a sub pixel channel match feature. My go with Pixinsight as well as reducing the saturation of your Red channel attached. Hope you like it!

Clear skies.

John K.

[turbo_pascale]

Hi John,

The RGB pixel align is just an analyses that lets you move the pixels 1 pixel at a time in any direction. Good, but no better than doing it manually in photoshop.

As for why RGB, well, I wanted to stretch it, to show the different colors you get in the mare which range from browns to blues.

I have a trial of pixinsight which I haven’t got my head around and it’s getting close to expiring. I’ll give that a try. Thanks.

How do all the planetary imagers do this? Or is it much more easy to hide because the images are normally a lot smaller? I thought I’d find more about this, but it seems I’m not searching the right things!

Ps. I hadn’t done and colour matching/grading yet. This is just the three raw stacks aligned as best I could.

[John K]

Hi Rob,

For the moon, I never shoot RGB. Only either an IR685 filter or a red filter.

For the planets - I simply try and always have a consistent histogram with all my filters. RGB align in Registax 6 works well for Jupiter, Saturn and Mars for the best alignment. The seeing can greatly affect this - Blue is always the blurriest channel. Adjustments in color balance in Photoshop also works.

What is probably working against you as well is that you are using a refractor if I am not mistaken - there will always be a slight color fringe so maybe this is what you are seeing.

Have fun.

John K.

[turbo_pascale]

Maybe I'm getting the workflow wrong.
I generated all three images in AutoStakkert3.
I then "aligned" the three images as best I could in Photoshop as an RGB TIF.
Then I bought that in to Registax to play with.

Is there a way to get the 3 final RGB images from AutoStakkert3 in to "automatically" align them? A lot of the planetary tutorials use OSC cameras and blow past this detail.


Yep, it's an APO (80ED) but that's a likely cause as well.

[John K]

That's the right workflow. RGB Align in Registax.

BUT - if you're really keen to play - then PixInsight is what you want. Either use channel match to move at a sub pixel level your different channels, or use the Star Alignment feature to align each channel and then simply combine them into an RGB image. I just had a go at this myself and I still see your red color fringe.

Have fun.

PS. I still think a grey image of the moon looks better - sorry but could not resist!

[turbo_pascale]

Totally agree - the grey scale ones look great.

I did this one with the Clear filter (as well as the LPS filter that I always run)
Full Size - https://astrob.in/qdqbdc/0/

I will get a colour one sorted eventually! I will crack out PixInsight. I've been staring at it anxiety ridden about the learning curve!

I did one last night also with my DSLR (Canon 7D MkII - 500mm Sigma lens)
https://astrob.in/ee2027/0/
But I had issues with it too - but I did manage to get the colour differences showing!

[Merlin66]

Could be due to atmospheric Chromatic Aberrations....