Lee_P

Thanks! I think that my background sky level is so high that 120s for L-eXtreme is way more than three times the optimal exposure when not using any filter anyway, and the limiting factor is storage space and PC processing power. So in effect my current method (120s for everything) is still valid for me given my local sky conditions. If I had much darker skies then it would be a different story.

Thanks @Budgie1 and @vlaiv, this is all great info and will definitely help me!

Here's my Elephant's Trunk using the same camera and filter, Bortle 8, and also following @Luke Newbould's excellent tutorial. Regarding halos around stars, I fix those as part of my standard workflow: after making a starless version using Starnet++, I then clean up any aberrations -- including the leftover halos -- using the clone tool in Photoshop.

I'd be interested in a link to that spreadsheet, if you have it handy. I've always shot 120s regardless of filter (i.e. no filter or L-eXtreme) and I've gotten good results -- happy to change my method if another one is more effective! Not quite sure of the logic though, as you get good signal from a high total integration time rather than individual subs, right? I'm tired, my brain might not be working properly...

@MHaneferd Good idea, I did the same experiment when I first got the camera. That helped me settle on 120s. That does look like a satellite in your 300s shot; what time was it taken? I'm in Bortle 8 too. It's a pain, but we can still get good images with long integration times. You'd get there faster from your cabin though! FYI your 120s sub looks better than my 120s sub:

Hi SGL Hive Mind, My current imaging project is M31 with my OSC camera. I'm close to 20 hours of RGB data (no filter), and would like to take L-eXtreme data to add in too, to get some glowing red hydrogen. I'm using PixInsight and haven't done this before, so am wondering if anyone can help; either by giving me some tips, a workflow, or link to a tutorial. My guess is that you process the RGB and L-eXtreme data separately and then combine them using some PixelMath wizardry..? I've done a bit of Googling but haven't found quite what I'm after. There are bound to be good resources out there that I'm missing! Thanks, -Lee

@MHaneferd Neat test! Remember that it's the total integration time that counts though. In principle your 100 x 120-second integration should be very similar to 200 x 60 seconds, or 40 x 300 seconds.

Thanks! I meant that the reference to 2-min subs was near the end of the article. I don't mention gain as that's not specifically about getting long integration times. A pier is indeed fantastic, I highly recommend them!

Just leave it on 100, job done.

@MHaneferd @Ouroboros Just following up on the "why gain 100" question, from ZWO's website: "The ASI2600MC Pro has excellent performance with a dynamic range of up to 14stops. When the gain value is 100, the magical HCG high gain mode is turned on, the readout noise is greatly reduced, and the dynamic range is basically unchanged. It is recommended to set the gain to 0 or gain 100 in deep space."

Are you using an electronic filter wheel with your OSC camera?

Gain 100. As for 2-mins, I mention that in this article, (point 3, near the end): http://urbanastrophotography.com/index.php/2021/06/14/how-to-get-long-integration-times/

Good job, some fine details starting to show through there.

This is a good start! Given your telescope's focal length, you might do well to centre in on a particularly interesting part of the nebula, like the Cygnus Wall. You need a much longer integration time though. As you suggest, shorter exposure times work well with a modern camera like the 2600. I use that camera too, and shoot 2-minute subs -- but lots of them! Aim to get five hours of good quality data in your image, then you'll have something nice to play about with in post-processing. This photo just posted by @StuartT might be of interest to you: same camera, similar telescope.

Welcome Dave, you've come to the right place to ask lots of questions! 😁

Yes, 100%. That's partly why I made my Urban Astrophotography website specifically about OSC from a city -- to try and give better / more up-to-date advice. And sometimes when people insist that Mono is the only option from a city, I show them this photo (OSC plus L-eXtreme, Bortle 8):

Well you are the CloudMagnet!

I image under UK skies and aim for around 20 hours per image. I produce an image approx. every one month with winter skies, two months in the summer.

Nice shot!

That's a cracking image, really shows what's possible even with a short integration time. I use a 2600 and L-eXtreme too, and was so impressed I ended up making a website! There might be some stuff there of interest to you: http://urbanastrophotography.com/

Good job, especially considering the Moon.

I'll put something together for them for a mere $51,000 😆

I like that phrasing! Wise words indeed.

Great!

Shout-out for Cygnus Astro covers, if you're in the UK. I haven't used a TG365 so can't make a direct comparison, but my Cygnus Astro is a lot cheaper, and still keeps the rain off! The chap that makes them can make you a custom size bespoke for your set up too.