Rosette nebula wide band workflow in LRC/Photoshop

[AdamAnt]

Captured ~2 hours of rosette nebula frames (60x120) using stock canon 70d and sigma 60-600 lens @ 300mm f/5.6 with 25 darks, 25 flats and 25 bias. All stacked in DSS and saved as 16-bit/ch embedded TIFF. Used Ioptron skyguider pro with auto guiding.

Have no clue on processing. Tried importing in LRC and moved a few sliders around in Develop mode but still don’t see any details of nebula just the core stars. Experienced photographer so know the camera and lens but complete newbie to any processing of images. Any help would be appreciated! 

 

Rahul

[TerryMcK]

5 hours ago, AdamAnt said:

Captured ~2 hours of rosette nebula frames (60x120) using stock canon 70d and sigma 60-600 lens @ 300mm f/5.6 with 25 darks, 25 flats and 25 bias. All stacked in DSS and saved as 16-bit/ch embedded TIFF. Used Ioptron skyguider pro with auto guiding.

Have no clue on processing. Tried importing in LRC and moved a few sliders around in Develop mode but still don’t see any details of nebula just the core stars. Experienced photographer so know the camera and lens but complete newbie to any processing of images. Any help would be appreciated! 

Hello Rahul and welcome to the forum.

You need to "stretch" the image.

Have a look at the tutorials from Trevor here https://astrobackyard.com/tutorials/astrophotography-tutorial-1/

[GazAstro]

Hi Rahul, real quick starting point ...

Try Siril as it's free and fairly automated.

 

Click Image processing - on drop down choose Asinh transformation

Adj stretch factor to lighten the 'light' bits and black point to keep the background fairly dark.

 

 

Then click image transformation - adjust the left (dark) and middle (nebulosity) to form a curve - dont pull the left one in too much as you will clip (lose) data

 

 

You can keep adjusting till you like the image.

 

You will probably see the image becoming greener as you stretch as a DSLR / colour sensor has 2 Green pixels for every 1 Red and Blue.

 

You can use remove green noise to balance the colours before trying colour calibration.

 

 

Finally, use one of the colour calibration methods, Photometric is very cool if you know the name of your image.

My image is mono so I can't show this in practice.

 

 

If you see a gradient from light pollution as you are stretching you can use background extraction to even this out.

 

 

Lastly, now you've had a dabble, try opening your original stacked image again and clicking on image transformation and the cog / curve button ... It has a crack at doing some of the adjustments for you ... but wheres the fun in that ? 🙂

 

 

 

This is by no means a full tutorial but It will bring out whats in the darkness of your stacked tiff.

 

 

Edited April 4, 2022 by GazAstro
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[AdamAnt]

Thanks, TerryMck and GazAstro! I will try these out and post the results.