Started 8 months ago | Discussions thread
OP jammeymc Contributing Member • Posts: 650
Re: NGC2244

Lyle Aldridge wrote:

Wonderful image! Thanks for sharing it.

I read the technical card to say that you combined images from two very different cameras, a ZWO ASI 1600 MM-C and a Canon 7D mark II DSLR. Can you give us, or direct us to, a thumbnail description of how that's done?

Thank you Lyle.

Indeed, i do use a side by side dual system. One RGB (7DII/AT65) and one mono with HA filter (ASI1600/GT81).

So when i'm finished, i will create a stacked file for both (ASI1600 and 7DMII). I will edit each stacked file individually and produce a final stretched file for both my HA image and my RGB image.

At this point i will :

  1. Register the two images with Pixinsight. This step can not be done with Deep Sky Stacker, as pixinsight can take files of different geometries, bit depth etcc., and then register them and scale them equally.
  2. Once the two files have been registered and are on equal scale, i open them both up in photoshop to begin my combining process.
  3. The first thing i will do, once both are opened in PS, is select-all the HA layer and copy it.
  4. I will then go into the "Channels" tab on the RGB file and paste the copied HA layer onto the "Red" Channell-layer of the RGB file.
  5. I will then use my levels/brightness/contrast controls on the new "RED" channell-layer to balance it in terms of brightness such that my overall red colors are balanced good with the other two color channels.
  6. I will then focus on the HA file again to stretch it a little more in PS. Once to taste, i will make another copy of it (select-all-copy).
  7. I will past this new copy ,as a new layer, within the RGB layer panel and put it on the very top. I will select "luminance" or "Screen" from the blending modes and experiment with them to taste. ( A tip - use the Screen mode when you want to use the stars from the RGB original file and use Luminenance when you want to use the stars from the HA file).
  8. At this point, you will use your opacity sliders within the layers tab to balance things out. Once you have a good opacity set, you can re-select the original RGB layer and add back in some saturation etc.....

There are a lot of steps to this type of process and it's harder to put it into words that it is to simply do it. Try stepping through these steps with a few of your images (if you do not have any mono files, make two copies of your RGB completed file and convert one to mono - and then stretch it hard to create an synthetic luminance/ha file).

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