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My first "NO EQ" DSO Images


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Hi everyone

I have been lurking on this site for a while, reading and assimilating all sorts of fascinating information about this wonderful hobby. Having acquired a secondhand Canon 50D camera in January, I thought I might be able to attach it to my scope for simple moon pictures etc. Then inspired by the amazing work of those contributing to the NO EQ DSO CHALLENGE thread, and by reading and digesting the book "Astrophotography on the go: Using Short Exposures with Light Mounts" by Joseph Ashley, I looked at DSO targets in the sky and was more than pleasantly surprised by what I was able to achieve with my limited mount and scope. I am trying out StarTools imaging software, and with BYEOS driving the camera using a mix of lights, darks, flats and bias, stacked in DSS have come up with the following pictures.

Yes, the CA is bad - I know this can be tackled in software, but to me it is part of the picture as taken - it is a cheap entry level scope after all. Yes, the background is poor and grainy - I have lots to learn about image processing and hope to pick up many more hints and tips on this subject as we go on. Yes, I am using the wrong equipment to image on, but it works for me for now until the Missus allows me more funds to play with! However, they are my pictures taken with my equipment and I am pleased with the results so far (plenty of room for improvement though!).

Question: No matter what I seem to try, I seem to always come up with a grainy background for my images - looks over processed. What is the most important factor at play here? Is it ISO level, poor SNR in the images, poor choice in targets to image, too aggressive with the imaging software, or something else? How do others manage grainy images? Would a light pollution filter help at all?

Thanks for taking a look, and may dark skies be yours when you wish them!

Andy

 

M42 Orion Nebula.jpg

M101 Pinwheel Galaxy.png

M104 Sombrero Galaxy.png

M51 Whirlpool Galaxy.jpg

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Hi,

Welcome to SGL!!! :) 

You certainly have a nice range of images there, on the issue of noise, it will always be an issue as you can't increase your sub exposure lengths indefinitely. Therefore you are pulling as much as possible out of your data. Taking LOTS (I.e., 50-100 + ) subs will reduce noise an enormous amount and increase the details you can get. Otherwise, it looks like you have got off to a great start! :) 

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Welcome! You've made a great start there Andy; I hope that you found Ashley's book of interest as it has some good advice for us non-EQ imagers. It can get you hooked :icon_biggrin:. It's also a way of honing your skills before committing much larger resources, and indeed, deciding if you do want to commit.

It's difficult to advise without more information about your set up - what gear are you using, how many exposures of lights, darks, flats and bias, exposure length and ISO? 

Ian

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Hi all

Thanks for the nice comments - I am really enjoying this hobby, and desperate for more clear nights. Ashley's book is almost nightly reading for when I can't get out as it has so much information, yes about short exposure astrophotography, but also about general principles for the beginner. Very helpful, as have all the posts on this subject in SGL.

Some technical info as requested:

M42 Orion: shot at ISO 800; 20 x 20s + 50 x 30s Lights; 60 darks; 40 flats; 30 bias

M101 Pinwheel: shot at ISO 400; 150 x 45s Lights; 40 darks; 40 flats; 40 bias (fighting against a full moon that night)

M51 Whirlpool: shot at ISO 800; 60 x 30s Lights; 60 darks; 40 flats; 30 bias

M104 Sombrero: shot at ISO 1600; 80 x 45s Lights; 30 darks; 40 flats; 30 bias

All stacked in DSS using prerequisites for StarTools taking 80% of good images; Images then processed in StarTools. I have been experimenting with ISO (as you can tell!) as looking at info on my camera, it seems that ISO 400 (possibly 800) is best to use for maximum dynamic range. Still learning processing with StarTools - however these possibly look overprocessed?

Thanks

Andy

 

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  • 6 months later...

I am not convinced by using darks.

Try a stack without darks and use your lights, flats and bias in case the darks are adding more noise. (edit: I am removing comment - and use an odd number of lights, flats and bias.)

Edited by happy-kat
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1 hour ago, happy-kat said:

I like to use odd numbers in my DSS stack and I am not convinced by using darks.

Try a stack without darks and use an odd number of lights, flats and bias.

Why so? I can't think of a theoretical reason why odd numbers should be better than even ones.

Ian

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I just like that and somewhere I read about odd numbers helping to mix up the algorithms on the stack I will see if I can find the comment.

Did find several references but no concrete proof so I will edit my comment to not include that.

Edited by happy-kat
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