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Dear all, On the first anniversary of my introduction to this fabulously interesting and rewarding hobby (and at times, frustrating / expensive!) I thought I would reach out and request some feedback on my recent image of the soul nebula: https://www.astrobin.com/ktb3wx/ I captured this using my esprit 100ED and ASI294MC pro from NE Scotland in a bortle 6 site. Its just over 12 h of total integration time across two nights (unsuccessfully dodging snow showers!) with an Antlia ALP-T filter and processed in pixinsight. I have been slowly inching my way up the rather steep pixinsight learning curve and this is the third image I have processed with a ton of help browsing forums and watching many, many youtube videos. Overall, I am quite chuffed with this image but I know that I can probably do more with this data. As I don't have the opportunity to visit a local astronomy club (or have any mates interested in astrophotography) I was hoping to get some feedback/suggestions from this wonderful forum. I was a little unsure of the crop and orientation of the image (its a bit different from most from what I can tell) and also wasn't sure if i overdid the colours. Could it also do with some more curves to increase the contrast? Any comments/criticism/suggestions warmly welcomed. Many thanks in advance. Alex |
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Honestly it really is very good to my eye. Stars look pretty round across the patch - good detail in the nebulosity. There are loads of possibilities in processing but they are just different and not necessarily better. For example you could possibly take some unfiltered OSC frames to get RGB stars and then extract these and replace them into the dual-band image so that you have true coloured stars? Things like crop, orientation and depth/ choice of colours are arbitrary really because there is no 'right' answer and especially with NB Don't worry either how many upticks you get because that is pretty arbitrary too. The IOTD pictures are often exceptional in terms of things like instrumentation, unusual choice of subject and location etc. Sorry -- non-advice really. Good as you are Tim |
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Tim Hawkes: Hi Tim Thanks so much for your thoughts, really appreciated. I agree with you, the stars could do with more colour so I might spend an hour or two catching some RGB stars. I saw a youtube video by Bill Blanshan about adding RGB stars to narrowband images so this looks like a good excuse to give his approach a go. I completely agree about upticks etc. I just do this for my own personal pleasure but its nice to have a wider community to be able to share images and experiences with. I don't have any options more locally, so having the opportunity to get some feedback from those more experienced is a real boon. Thanks again. Alex |
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Alex, Excellent image! I think you've done a very nice job processing the data. Bill's pixel math expressions are fantastic - I use them, too  .I have 2 very minor critiques, and they are based on my own tastes, not on anything technically wrong with your image. The first is noise reduction. In my opinion, you went overboard and went for noise elimination. I would dial that back a bit. It'll help to bring out some more detail in the nebulous clouds. The second is the star reduction. Again, I think you went a bit heavy-handed. If you're using Bill's process icons, I typically find the "method 1" to be far too aggressive. Again, these are minor things and are based solely on how _I_ would edit the data. You've got nice, round stars across the image. You've captured a nice framing of the nebula and have brought out some very nice details. You've done a nice job with the colors, too - not over saturated. |
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Hi Jonny, Thank you for your really helpful comments. Noise reduction is something that I generally struggle with. I guess it takes experience but I often find it difficult to strike a good balance between reducing noise and retaining detail. I have played around with both EZ noise reduction and noiseXterminator but i think I tend to go a little bit too far. I'll try to bear your comment in mind when I process my next image! Thanks also for highlighting my stars. I haven't too much experience with processing astro images but the more great images I see (and there are loads on astrobin) the more I realise that it is often the stars that make them great. Frankly, I don't spend nearly enough time on getting the best out of my stars and this is something I want to try and focus on. Thanks again for your feedback. Alex |
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| @Alex Douglas I'm a big fan of Russ Croman's tools. I own Blur, Noise and Star Xterminator for PI. You are definitely not alone in your struggles to strike the perfect balance of noise reduction. I like NXT's ability to use sliders to change not only how much noise reduction is done, but also how much detail it tries to preserve. I'll usually run a dataset through NXT multiple times with various settings of the sliders to see what I like best. Stars can be quite hard to get right. They tend to saturate your sensor very quickly - especially when you're shooting long sub-exposures for narrowband imaging. One method you might want to consider is using short exposures with only a UV/IR cut filter, then merging those RGB stars into your nebula data. You don't need a lot of data... you're not trying to capture background details, just the stars. |
