Gonzo Posted August 11, 2023 Share Posted August 11, 2023 (edited) Redcat 51 + 533MC pro (IR cut filter only), processed in Siril 1.2.0RC1 (with starnet++), bortle 4 (in Germany), CEM25p 60x120sec lights + 25 darks + 50 bias and no flat, unguided Edited August 11, 2023 by Gonzo forgot the mount 8 Link to comment Share on other sites More sharing options...
peter shah Posted August 11, 2023 Share Posted August 11, 2023 beautiful shot... lovely of detail Link to comment Share on other sites More sharing options...
Gonzo Posted August 11, 2023 Author Share Posted August 11, 2023 Thanks. The core is too bright I think, I need to find some blogs on how to deal with that. Link to comment Share on other sites More sharing options...
Phillyo Posted August 11, 2023 Share Posted August 11, 2023 Lots of lovely dusty detail there, but there doesn't seem to be any colour in the image? Was this shot with the OSC version or mono version? Link to comment Share on other sites More sharing options...
WolfieGlos Posted August 11, 2023 Share Posted August 11, 2023 10 minutes ago, Phillyo said: Lots of lovely dusty detail there, but there doesn't seem to be any colour in the image? Was this shot with the OSC version or mono version? I thought the same, and noticed it’s stacked with Siril. Siril does the same with me although I use a DSLR, and my M31 was more of a brown hue. I have to use ASTAP to stack for galaxies or globs or else I get the same lack of colour. Nice image though! There is a stacking remnant across the top to be cropped off though. Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 8 hours ago, Phillyo said: Lots of lovely dusty detail there, but there doesn't seem to be any colour in the image? Was this shot with the OSC version or mono version? I only have the colour version of the 533. Link to comment Share on other sites More sharing options...
Phillyo Posted August 12, 2023 Share Posted August 12, 2023 2 hours ago, Gonzo said: I only have the colour version of the 533. Then there should be a lot more colour in your image than shown above. Have you ever used Deep Sky Stacker to stack the image, then processed in something like photoshop (or GIMP (the free version)). You should be able to bring out a lot more colour data? Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 I used Deep Sky Stacker many many years ago, however I'm on a Mac and I don't think there is a version for it. I do not have Photoshop, but I have Gimp as it's free. Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 These are the red/blue/green/RGB channels from Siril, maybe I'm doing something wrong somewhere. Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 22 pages of it... https://www.cloudynights.com/topic/841663-lost-color-in-siril-calibration/ 1 Link to comment Share on other sites More sharing options...
Phillyo Posted August 12, 2023 Share Posted August 12, 2023 Unfortunately I've never used Siril so I can't help much there. I use Pixinsight for everything. Seems strange you're getting no colour in your image though as there's obviously a lot of data in each channel. Link to comment Share on other sites More sharing options...
WolfieGlos Posted August 12, 2023 Share Posted August 12, 2023 2 hours ago, Gonzo said: 22 pages of it... https://www.cloudynights.com/topic/841663-lost-color-in-siril-calibration/ Yeah, I followed that topic briefly and got completely lost and confused. Way above my head! There is an old discussion on Siril's forums here: https://discuss.pixls.us/t/m31-andromeda-why-is-siril-making-it-appear-mauve-brown/20934 - that result is exactly what I got for M31, the conclusion seemed to be to try stacking with ASTAP, so that is what made me try it and it worked. I find that ASTAP isn't quite as good at removing satellite trails, usually the very bright ones get some artifacts left in, but nothing that clone stamping can't resolve. I posted about it when I imaged M63 earlier in the year with a comparison here: https://stargazerslounge.com/topic/409905-m63-sunflower-galaxy/#comment-4381252 - and found exactly the same. It might be in white balance, colour balance or even possibly how Siril converts the files, I don't know. I just know that ASTAP gives a more colourful result. I now stack all galaxies and clusters with ASTAP - I've found globular clusters to have the same net result of colour loss in Siril. Nebulae I still use Siril but I haven't tried one with ASTAP yet to compare, but I intend to when I get some more imaging time. The other option is to use Pixinsight or APP, but I don't own the software to try. 1 Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 28 minutes ago, Phillyo said: Unfortunately I've never used Siril so I can't help much there. I use Pixinsight for everything. Seems strange you're getting no colour in your image though as there's obviously a lot of data in each channel. I do have Pixinsight, but it's on my main computer and not on my laptop. I use Siril on the laptop. The main computer is still in a box as I've just moved country and still have lots to unpack... 1 Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 9 minutes ago, WolfieGlos said: Yeah, I followed that topic briefly and got completely lost and confused. Way above my head! There is an old discussion on Siril's forums here: https://discuss.pixls.us/t/m31-andromeda-why-is-siril-making-it-appear-mauve-brown/20934 - that result is exactly what I got for M31, the conclusion seemed to be to try stacking with ASTAP, so that is what made me try it and it worked. I find that ASTAP isn't quite as good at removing satellite trails, usually the very bright ones get some artifacts left in, but nothing that clone stamping can't resolve. I posted about it when I imaged M63 earlier in the year with a comparison here: https://stargazerslounge.com/topic/409905-m63-sunflower-galaxy/#comment-4381252 - and found exactly the same. It might be in white balance, colour balance or even possibly how Siril converts the files, I don't know. I just know that ASTAP gives a more colourful result. I now stack all galaxies and clusters with ASTAP - I've found globular clusters to have the same net result of colour loss in Siril. Nebulae I still use Siril but I haven't tried one with ASTAP yet to compare, but I intend to when I get some more imaging time. The other option is to use Pixinsight or APP, but I don't own the software to try. Thanks for the info and links. I shall try this ASTAP thing and see how it goes. 1 Link to comment Share on other sites More sharing options...
WolfieGlos Posted August 12, 2023 Share Posted August 12, 2023 3 minutes ago, Gonzo said: Thanks for the info and links. I shall try this ASTAP thing and see how it goes. Good luck, let us know how it goes! The few discussions I've seen of this are all linked to DSLR's so it'll be a good comparison. ASTAP is free software, previously I only used it for tilt checking, but I have since used it to create Mosaics and also now stacking. It seems to be an under-rated and under-used piece of software IMO. Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 Stacked with ASTAP (just lights and dakrs, with software settings left as they are) and just an auto-stretch in Siril Link to comment Share on other sites More sharing options...
ONIKKINEN Posted August 12, 2023 Share Posted August 12, 2023 (edited) Its a very nice M31, would comment on the Siril colour thing further. That cloudy nights thread is frankly full of people who comment on the "issue" without understanding what it is that Siril does when stacking. Personally would not recommend reading through that thread without a few pints, and even then would not take any advice from it. Or more importantly, what it does not do. Siril does not apply any type of pre-stretch to any of the channels when calibrating which is something that some other software do. This is typically useful for daylight photography but for astrophotography it should not be applied because you want to have the data as linear as it could possibly be after stacking. So you can extract anything you want from the fully linear Siril stack, but you cant "unbake the cake" if the daylight colour transformation gamma nonsense is applied. This kind of colour transformation makes the data non-linear and certain processes like a photometric colour calibration will fail because fully linear data is expected. Now a helpful tip: Start processing with a crop, a background extraction, colour calibration and a stretch (in that order). To stretch the colours, or maybe better to say stretch the image while also better preserving colour you can start stretching with the Asinh transformation tool. I typically apply it at the full 1000 power, but sometimes that could be too much and you could go for something like 300. If the colours look deepfried at 1000, dial it back to maybe 300 and see what you get. Its also possible that the 1000 power stretch is still a bit dull, for which you could apply Asinh again at a small value like 20-50 (experiment on this) After this you can stretch with the simple histogram transformation tool to finish the stretch. You will see that the colours start to appear and they were not lost in the process somewhere. Below some examples from one of my own M31 images. First, only an autostretch in which the colours appear "muted": Then an Asinh stretch at 1000, followed by 25 and finally a closer dial in with the histogram transformation tool (manually, autostretch is way too much): For the second one i paid very little attention to colour calibration so it looks a bit off but i think you'll agree the colours are there to see and further adjust however you like. No extra saturation applied. This is also a mosaic image where the panels dont quite blend in properly so there are extra complications. For a simple one panel image it is much more straight forward. There is also another thing, M31 doesn't actually have a lot of the vibrant blues and purples you sometimes see in processed M31 images, so what you see in the simple stretch version (and your versions) is closer to "reality" than those blue/purple ones. Wouldn't claim that one is objectively better than another of course, i think the subject of colours is highly subjective anyway. Edited August 12, 2023 by ONIKKINEN 2 Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 Thanks for the detailed response, I shall try the Asinh transformation tool. Overall I'm quite happy with the capture, but I do need to get my main computer sorted out to be able to work with Pixinsight and on a large monitor instead of the laptop... Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 @ONIKKINEN This is what I came up with, using the Asinh transformation tool and following your "Start processing with a crop, a background extraction, colour calibration and a stretch (in that order)" It really does look way better now (I think) than the one I've posted at the start of this thread. 1 Link to comment Share on other sites More sharing options...
ONIKKINEN Posted August 12, 2023 Share Posted August 12, 2023 11 minutes ago, Gonzo said: @ONIKKINEN This is what I came up with, using the Asinh transformation tool and following your "Start processing with a crop, a background extraction, colour calibration and a stretch (in that order)" It really does look way better now (I think) than the one I've posted at the start of this thread. On a decently calibrated computer monitor it looks a bit green but does have a lot more life in it. Might not be noticeable on every display though but it is on both of mine. Try "green noise removal" after the first Asinh stretch? You can also try before, or at any other point after colour calibration. 1 Link to comment Share on other sites More sharing options...
Gonzo Posted August 12, 2023 Author Share Posted August 12, 2023 Cool thanks for the tips, I'll try the "green noise removal". Link to comment Share on other sites More sharing options...
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