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Hi, I just got my 268M with CFW3 and 36mm Baader filters. So, what gain do you use? According to the QHY website, you should start with mode #0 and gain 26, which I will do, if the clouds sometimes vanish... What is your experience? Anybody using modes #2 and #3? Clear skies, Chris |
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I got the camera recently, also still experimenting . Did few images with narrowband . Used mode 1, gain 60 offset 45 with SHO filters and gain 0 , offset 40 with RGBs . That was in Bortle 5 , with LED streetlights around. Two SHO images are here in my gallery . |
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Stjepan Prugovečki: Hi Stjepan, nice results so far! Did you use any dark frames? It doesn't look like darks are needed any more with this sensor... CS, Chris |
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I did use darks, however, more the habit than real need . Especially if you dither , stacking process takes good care of hot/cold pixels. As it was cloudy/rainy when I got the camera I just made a library , so I am using it on "does not harm , but does not help much either" principle. . I have also color version of the same sensor and in fact stopped to use darks there.
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There was a discussion on Cloudy Nights last February about optimal settings for mode 1 (high gain mode). The consensus was that Gain 56 was a good choice. Qiu Hongyun from QHY stopped by and recommended it for short exposures. I have been using Gain 56 with offset of 10 since I got the camera, and the results are excellent. [url=http://Cloudy Nights discussion]https://www.cloudynights.com/topic/754530-qhy268m-read-out-modes-questions/[/url] I also have Baader 36 mm filters, so your setup has some similarities to mine. The camera and filters are being used with a Sky-Watcher Esprit 100ED. One issue I have encountered is halos around brighter stars in RGB images, especially the blue stars. I need to remove halos with software every time I process an image. I cannot say for certain that the filters are responsible, but I think it is likely. The Baader H-alpha filter performs well, with minimal halos, and the red filter is also reasonably good. It's the green and blue filters that have halo problems with the optics I am using. |
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There was a discussion on Cloudy Nights last February about optimal settings for mode 1 (high gain mode). The consensus was that Gain 56 was a good choice. Qiu Hongyun from QHY stopped by and recommended it for short exposures. I have been using Gain 56 with offset of 10 since I got the camera, and the results are excellent. Thanks for your reply and for the link to CN. Yes, according to the diagrams on the QHY-website, gain 56 for mode 1 and gain 26 for mode 0 are the optimum starting points. And gain 60, mode 1 is the best point regarding the dynamic range, as Stjepan uses. Well, as usual, the only imaging, I can do with a new camera, is doing darks, biases and flats... Do you use the new generation Baader "CMOS-optimised" filters? They should not have that strong halos at all! |
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My LRGB filters are Baader CMOS optimized, the latest generation and indeed some slight halo pops up on blue filter. I used it only on Esprit 120. Will try to compare with C8 Edge HD and with Esprit without focal reducer . I have Antlia 3nm SHO and there are no severe halos on OIII . Halos are actually more visible on Ha , but nothing really worrying . |
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| My Baader filters are fairly old, so it seems likely that I will buy a new set in the spring to address the halos. I should have mentioned that they are not new filters in my original post. |
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Stjepan Prugovečki: Yep, regarding the prize of the CMOS-optimised filters against Antlia (and more so Astrodon and Chroma), it is obvious, that there must be some flaws :-) I will see, how they perform in my setup. |
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My Baader filters are fairly old, so it seems likely that I will buy a new set in the spring to address the halos. I should have mentioned that they are not new filters in my original post. So, it looks like, the Antlia should be the most efficient solution. I think, there are some LRGB from Antlia available, too. |
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So far , from what I tried I am quite happy with both . Baader was a bit cheaper and available . Can't exactly complaint on Baader as halos are not really worrying ,and also I am not sure that I have put the right sides towards the camera. It says somewhere that there should be small arrows marked on the filter edge to point to the right side, but I could not find it. Long story short , I am happy with what I saw so far , with both Baader and Antlia |
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We've been using high gain mode, gain 0 with lots of success. Looking at the published graphs, these settings seemed to offer the ideal blend between full well, read noise, and dynamic range. This works well for 5 minute broadband frames and 10 minute narrowband frames at F6.7. If you chose to use settings to reach a lower read noise at the expense of full well, I'd strongly reccomend dropping your exposures to no more than a minute to prevent saturating too many pixels. Jon |
