Questions & Answers/Tips & Tricks => Newcomers Corner => Topic started by: Annie on 12:03:59, 02 December, 2017

Title: NGC7635 image for C & C
Post by: Annie on 12:03:59, 02 December, 2017
Am wanting to improve my basic imaging techniques and also my processing so wanting some constructive criticism on some recent images.  I took this one last week of the Bubble nebula when the moon was around: 21x600sec exp at ISO800 with Takahashi 106ED, crop sensor Canon 550D DSLR and Lacerta MGEN guider.  Stacked in DSS with darks and flats and processed in PS (with my usual limitations!).  The image is uncropped.


Title: Re: NGC7635 image for C & C
Post by: Nimbus on 18:33:01, 02 December, 2017
Hello Annie,

Firstly, you have a pleasing image and it is always less than easy to comment on a Jpg of restricted size,  but here are some observations from me:

You mention you applied Darks and Flats - no Bias? Bias are need also.

There appears to be a dark circle at about 7 o'clock to the bubble  indicating the Flats may not have dealt with any artifacts.

Overall the image appears a little dark for my taste indicating there may be some black clipping.  Try aiming for a background of about 30-40 in the info palette.

I suspect there is more nebulosity hidden in the original image that means you can stretch things a little further.  You may wish to remove the stars first to prevent bloating.  You can layer the stars back in and tighten them up to reduce there dominance in the image.

The colour balance appears a little off, try aligning the left hand side of each of the RGB histograms to achieve the correct balance.

The good news is you have retained some colour in the stars which can easily be lost when stretching.

Have a go at adjusting your original image in line with the above and re-post and we can see where we go from there. If you are not sure how to achieve the above any of the techniques - ask away.

Title: Re: NGC7635 image for C & C
Post by: Annie on 19:24:24, 02 December, 2017
Hi Jim - thanks for some helpful comments.  Firstly I just forgot to mention the bias but I did add them and you're right that the flats didn't get rid of all the artefacts.  I take my flats using a head torch with something over it to diffuse the light but my torch packed up so the flats didn't work very well! I can try most of what you suggest other than removing and layering the stars back in but I guess that would be a bit difficult to explain so am happy to try and work that out!!

Thanks again Jim

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