Starwiz

Noise is an unfortunate product of higher temperatures. I usually image at -10C with my ASI1600mm, but once forgot to cool it, so it was operating at +28C. The amount of noise I saw on the first image was striking. Obviously, you can't cool the DSLR, but more frames and dithering will help significantly. I'm usually working with hours of data for Ha even with the cooled camera. As Wim said, you may need to expose for longer too. Part of this is to overcome the read-noise of the camera. i.e. the signal needs to be much higher than the read noise. John

Ha ha ha. You don't want to see the bites on my legs. lol

There are a few tutorials on how to removed the stars. To add them back in, create a layer with just the stars, then set the blend mode to 'Lighten' for this mode. Another technique you could try (if you're already happy with the star colours), is to use a star mask so the stars aren't affected when you do the stretching. I was using narrow band (horrible bloated magenta stars) so wanted to replace the stars with RGB. John

That's impressive considering the constraints you have. John

Nice image. I've been using -10 as standard out here in Malta. There's only a small difference between -10 and -15 and even less between -15 and -20. John

Have you tried star removal before stretching, then adding the stars back in afterward. I did this for the first time with my last image. It's a ton of work, but I was pleased with the results. Nice image BTW. John

Spectacular! A wonderful image. John

Very nice. What colour mappings did you use for the Ha and OIII? John

Wonderful result and I can see the pillars in there. It's low down for me even in Malta You should be proud of this image. John

Good stuff. I can see the pillars in there. John

Looks more impressive and earns you extra kudos points when showing it to family and friends. 😀 John

Well done! As an interesting exercise, you could note the time you took the photograph, then research on the web to see what position the moons where in at the time of the photo. This will allow you to identify each of Io, Europa, Ganymede and Callisto in your photo. e.g. https://s22380.pcdn.co/wp-content/plugins/observing-tools/jupiter_moons/jupiter.html You'll need to take into account the orientation of the image, if your telescope inverts it, etc. John

This usually means it's very good for planetary imaging where you want stillness in the atmosphere. For DSOs. transparency is what you want. Not necessarily a non-turbulent atmosphere, but less haze and better contrast. etc. John

Maybe, just a bit. Sorry, couldn't help it. lol 😀

Been there, done the apprenticeship. OK, maybe I did enjoy the winter too, although maybe not as cold as the western highlands!

Sorry, didn't mean to 'rub it in,' so to speak. Back in the UK, I used to enjoy summer astro-imaging more than the winter even though the results were better in the winter, but out here is the best of both worlds, so I can sit outside in a t-shirt and play with the kit, and have a cold beer to keep me chilled. John

Long clear nights too - almost seven hours of astro-darkness at this time of year. 😎

Thanks, that's useful. I also used 180s @ 200 gain a couple of nights ago. I haven't touched the offset, so it's on whatever the default is. I tried 300s @ 200 gain last night for Ha, OIII and SII, so just waiting for the darks run to finish before I have a look what I've got. I'm in a Bortle 5. John

Looks good. What exposure lengths and gain are you using and what's your sky Bortle? Just interested as I'm still trying to decide what's best for me. Thanks John

Thanks. John

If it helps, here's what I do........ Add the lights and run registration only, no stacking. Note the sub with the highest score, so this can be used as the reference frame. I rename this file and copy it to it's own location, so I can use it with Ha, OIII subs, etc. Registration needs to be run again after renaming. I also check all the other scores, so when stacking, un-tick anything below 300 before stacking, or if I'm using it for a luminance layer will un-tick anything below 1600 as I want the detail to be as sharp as possible. In the other tabs, I add the subs from each night, each to its own tab. You can re-use the calibration frames for each tab if needed, by copying them to separate folder locations. DSS looks at the complete path, not just the file name to decide if a file is the same as a previous one already loaded. If the calibration frames are in the first tab, they will affect all other frames regardless of which tab they are in. If they are in another tab, then they only affect that tab. So I put calibration frames into each of the other tabs and just leave the reference frame in the first. If the reference frame is from Ha and I'm stacking OIII for instance, then make sure the reference frame is un-ticked before stacking. John

Ah, now I understand.

I've been using 2x2 binning for OIII and SII with my ASI1600mm-Pro, but does anyone use higher, such as 3x3 or 4x4 and is it beneficial to do so? Thanks John

I could do with improving my star shapes towards the edges of the field. How does spacing affect it? I thought the image would still focus to the same place if a spacer is added for instance. Thanks John

Thanks.