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Lee_P

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Everything posted by Lee_P

  1. You could check here: https://www.lightpollutionmap.info/ I'd have guessed you'd have darker skies than Bortle 6 to get that much detail in just 8 minutes!
  2. Ok, I followed your thorough instructions with a few modifications that may have messed things up -- I saved as TIFFs so I could put them into Photoshop. Then once I'd adjusted the levels, I saved as 16bit so I could export as JPEG for the GIF. This is my result. I don't see the noise level going down appreciably, but I do see an increased gradient. Here are the FITS files. If you've got the time, I'd be very interested to see my experiment done properly! 24.fit22.fit20.fit18.fit16.fit14.fit12.fit10.fit8.fit6.fit4.fit2.fit Thanks, -Lee
  3. Thanks, that's very kind. I'm here to learn, so I'll glady take you up on the offer of showing me how to do it in ImageJ. I've downloaded the software. If I fail then I'll take you up on your offer of just doing it for me
  4. Nice pics! Back when I started with my camera I did some tests, and found that Darks + Flats gave me the best results. I might try again though, as I'm learning a lot about how to make proper comparisons.
  5. That's a great picture, especially for such a short integration time. The images in my test just had some very basic edits done, to allow them to be compared fairly. This is a fully edited version with 24 hours of integration time. Looks a bit better than my simple tests: What level of light pollution do you have? I'm going to guess you're imaging from some nice dark skies? I'm in a city centre, which puts me at a big disadvantage with broadband targets like M81.
  6. It looks like the images are 32bit, but the statistics panel only has the option to display info for up to 16bit
  7. Ok, thanks, this makes sense to me. I tried it and something is amiss, as after my PixelMath subtraction, the median value isn't 0. Could someone versed in PixelMath point out where I'm going wrong? Before PixelMath. Median value = 29. My PixelMath expression to remove the median value: After subtraction, the median value is 4. Shouldn't it be 0? Further proof that I've got it wrong. The left half of the image is 2 hours of integration, the right half is 24 hours. These are after my evidently suspect process of subtracting medi
  8. I've been trying for the last hour but just can't crack the normalisation stage. I'm sure it's simple, so I need to find some tutorials. I'll pause this for now, but thanks for all your help!
  9. Thanks vlaiv, this is pure gold. I think I'm getting my head around it... I tried reproducing your example. I find it useful, but did I mess up the "linear stretch" aspect? If you could give me a pointer on how to do that in Photoshop, maybe I could make a version 2. And here's a graph of noise against integration time. Thanks again! -Lee
  10. Oh, you're clever Looks like the noise level is going down? Here's the noise level over 24 hours of data: So thanks to this and @vlaiv's insight, I think I understand that the noise level *is* going down, it just doesn't appear to in my GIFs because the process I used was automatically stretching it. BUT! I still don't understand why the noise pattern is the same in every image. Is that because of the automatic stretching? To answer your other question, here's M81 over 24 hours: And a version of the same data adjusted in
  11. Ok, interesting. Could be worth me investigating. Thanks!
  12. Interesting, I thought that ABE / DBE appears to introduce noise because they're removing gradients (e.g. from light pollution) that are essentially masking the underlying noise. If that makes sense? I could be wrong! I am indeed making my way through Adam Block's WBPP2.0 videos -- it's those that prompted me to make the tests including FlatDarks and CosmeticCorrection!
  13. Thanks vlaiv, I'm going to read all that carefully -- for now, attached are four FITS stacks 90_mins_darks_and_flats.fit 105_mins_darks_and_flats.fit 120_mins_darks_and_flats.fit 135_mins_darks_and_flats.fit
  14. FYI I've conducted a few more tests and have started a new thread about this:
  15. Hi SGL Hive Mind, I’ve got a real head-scratcher of a problem, and I’m hoping someone here can help me solve it. I’ve been experimenting with seeing the effects of increasing integration time on background noise levels. My understanding is that the greater the total integration time, the smoother the background noise should appear. But I’m finding that beyond one hour of integration, my noise levels see no improvement, and even maintain the same general structure. I flagged this in another thread but think it deserves its own thread, so I thought I’d begin anew. I figure
  16. Price reduced to £80, inc. recorded delivery to a UK address. Offers considered.
  17. I've tried using DSS but can't get a decent image out of it, so obviously I'm doing something wrong. Why is nothing ever easy?!
  18. You might need to be signed into a Google account? https://drive.google.com/drive/folders/1simtZOsVAgwuqIT44uMkJ_a_jzGvhE3n?usp=sharing I used PixInsight. I'm a relative newbie, so wouldn't be surprised if I were doing something dumb that's causing the effect. Here are my settings:
  19. @CloudMagnet @Ouroboros @ Anyone Else That's Interested Could we try ruling out user error? Seems that me having messed up the pre-processing or integrations is a possible cause for the noise pattern. I've uploaded the files from the latest test here: https://drive.google.com/drive/folders/1simtZOsVAgwuqIT44uMkJ_a_jzGvhE3n?usp=sharing Any chance you could try some integrations and see if you get the same effect? No worries if that's too much hassle for you! FYI the Lights folder contains the 10px drizzled data. The file that begins "REF" is what I used for my reference file. If you w
  20. I reckon it's 10 pixels on the guidecam. That's the highest possible setting, so I'd be surprised if it weren't enough. Re: stretching, I used EZ Stretch in Pixinsight.
  21. Lights are integrations of two-minute exposures. Flats taken using my ASIAIR PRO's auto flat exposure, which came out as 2.7s. Dark Flats 2.7s too, to match. Gain 100.
  22. @Ouroboros @CloudMagnet I've made a few more noise tests: increasing the dithering, and trying Dark Flats. Nothing seems to make an appreciable difference in the end. So either I'm getting something wrong in the image acquisition / pre-processing stages, or my Bortle 8 skies are forever cursed to have this level of background noise. I've been staring at these images for hours though, so maybe some fresh eyes can spot something I'm missing!
  23. Price reduced to £90, inc. recorded delivery to a UK address. Offers considered.
  24. I'm using an ASIAIR PRO, with the dither options being 1, 2, 3, 5, or 10 pixels. I've been using 3. Sounds like another test is called for, with a higher number. The variations being real is something I hadn't even considered
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