Comet Leonard - 1st January 2022

[TerryC]

Taken last night, this one is 40 x 30 sec exposures using a 102ED f/7 non-guided scope, live stacked in ASIAir Pro.

Still learning to process with Photoshop. Would appreciate any tips on getting a darker sky whilst maintaining the finer detail in the comet tail.

Happy New Year !

[foc]

Nice Comet Terry..very smooth and elongated tail, light pollution must be not too bad where you imaged.

[JA]

Nice image Terry. to get a darker sky and TRY to maintain comet detail try....

1. Open image in Photoshop
2. Click Adjustments tab
3. Click Curves Icon
4. On Left Hand side of curves graph Click the Black Point EyeDropper (Topmost eyedropper of the 3 shown -NOT the grey or white point eyedroppers). The cursor should now change from a pointer to an eyedropper shape. Anywhere on the image where you now click (in the next step) will be the NEW reference level for BLACK
5. Move the cursor/eyedropper to an area of mid grey in your image and left click the mouse. The sky should be darker and the comet mostly unchanged except for some unfortunate reduction in length due to the vignette in your image.
6. if unhappy with the result, UNDO with Control Z or undo in the EDIT tab top left and try another area, you will soon get the hang of it.

There is a sample below of what's possible.

That was an easy way to do it across the image, but perhaps if you want to maintain all the tail length you could mask or select only the comet or invert select (everything else) and reduce the exposure with a smooth feathered edge. More complicated I didn't try that.

Best
JA

[TerryC]

Thanks Ross. I should have mentioned I used a L-Pro filter - needed for my Bortle 6 location...

[TerryC]

Thanks JA, will give it a go !

BTW, I could not see your example...

[JA]

Sorry I was reworking it, the easy way to try to retain more tail, but to no avail. It would be better to selectively mask and reduce the exposure of the sky instead. anyway here it is as per original blackpoint eyedropper suggestion.....
285155

Best
JA

[TerryC]

Thanks for trying, certainly gives a nice dark sky though. Just trying to work out the steps for selecting mask and inverse to reduce the sky exposure - seems to be the way to go.

[JA]

It's an OK method to try to see what might be possible with selective masking and it's certainly better than just reducing the exposure over the whole image, BUT the best result will be by selectively masking the comet, using a feathered edge to the selection (experiment with its width - start at 100 pixels), Invert selecting everything else except the comet (i.e: the sky) and reducing the exposure about 2 or 3 stops.

Best
JA

[Anth10]

Terry,
I tried this in similar conditions prior to Christmas and found the gradients in my image almost to difficult to smooth out and darken given it was swamped in Melbourne’s light glow. I used ‘Color Range’ to select the comet tail to enhance the far reaches and then tried to lower the exposure separately on the background by the same method. JA’s tip looks to be the way to go albeit sacrificing the fine tail tips.
Tough gig.
Anthony

[TerryC]

I agree Anthony, just tried exactly what you did without success. The lack of a dark sky near the comet head at twilight is the basic issue.

[TerryC]

This is as good as I can get it without sacrificing too much tail !

[JA]

Hi Terry,

I mucked about with selectively masking the comet and adjusting the exposure of the background and ended up with a darker background for sure, but it ended up a little washed out (version NOT shown).

The version below does not use selective masking and achieves a better result than the selective masking version I tried. I used a grey point and white point adjustment and hey presto... most of the tail retained on a darker contrasty background. With more effort one could even kill the dust dots in the lower left, but they're also greatly reduced with the above adjustments. Another bonus, with the darkened background the star colour is a little more evident - See the large bluish star on the left side of the comet versus the large orangish star on the right side of the comet. Less really is more !

If it were me, I'd be happy with that as a result, given the conditions you imaged under and the starting point (I used your smallish 85.6kB JPEG above).

Best
JA

[TerryC]

Nice one JA. I'll play around with those settings :thumbsup: