wimvb

That actually makes sense, since with a 12 bit ADC (zwo cameras) the 12 bit output is stored in the high end of a 16 bit word; 1 ADU = 16 DN. (16 = 2^4 where 4 =16 - 12.) 0.48 e/ADU = 0.48/16 e/DN = 0.03 e/DN Good thing I wrote "afaIk" before, because I didn't then, but now I know farther. Always nice to learn new stuff.

AfaIk, DN and ADU are the same, a digital unit. Otherwise, I can't help, I've never come to grips with Mure denoise.

If you're imaging from a lp area (bortle 8+), you should probably reconsider the dslr as an option. Mono + rgb is generally more lp-proof than osc because rgb filters have a transmission gap at the most dominant wavelengths for light pollution sources. Some rgb filters are better in this respect than others. You may also need to adopt a different data collection method than standard lrgb, because your luminance will collect all the light pollution. Rgb filters combined with Ha and Oiii in a 5 filter wheel and a camera with a smaller sensor may be the way to go.

The OP's view on that was given in the original post: 😉 Performance-wise one could go either way, imo.

Another no brainer: pixinsight; since you can't do anything with your data without processing software, and Gimp crashes/is limited.

Your stars are out of focus. 😉 Seriously though, nice setup.

I know, hence the . The asiair pro must have a power adapter built in.

So, how is this pro-gadget powered? Through usb-c with step up converters to get 12 V out? The zwo- & dslr only support is probably a combination of strategy and licensing issues. Does anyone know if it's possible to test the app without buying the hardware?

With all due respect, it doesn't have to be meaningfull, it just has to work. Göran, try a shorter distance next time and see if that either solves the problem or gives star shapes as in the other image. If it does, you know in what interval to look. 53 mm seems as good a value as any to start.

Same here. If I subtract 54.5 mm from the TS table values, I can fit a straight line in a log-log lin-log diagram. This means that for infinite focal length, the optimum distance is 54.5 mm. That's close enough to 55 mm. "Infinite focal length" is anything larger than 900 mm in practice. When ZWO do the calculations for the optimum distance for their filter wheels and cameras, they use a back focus of 56 mm, having added 1 mm for the added optical path increase due to the filters. But Göran has an osc, so that shouldn't apply. I'm out of ideas.

If you invest in the sw eq3 upgrade kit, you can have a very nice tracking mount for a dslr with a lens. With a moderate telephoto lens you can get widefield images of the Andromeda galaxy as well as the moon. You can then also start looking into guiding, something you'll eventually need anyway. Go for the goto upgrade kit with synscan if that's an option moneywise.

I hate to bring you the bad news, but your telescope and mount are not suited for AP, imo. The 150PL is not an imaging scope and may not reach focus with a dslr. The 150P-DS is the imaging version of this scope. It has both a shorter focal length and a shorter tube (for its focal length). Furthermore, your mount does not have the capacity to carry this long scope with a camera. If I were you, I'd enjoy this combo for visual use and save up for (and read up on) a combination of mount and scope better suited for AP. A budget mount that performs quite well is the SkyWatcher heq5. Pair this with either a refractor (ed80) or a reflector (150P-DS) and you have a setup that should bring you a lot of imaging pleasure. If lack of funds is an obstacle, consider buying second hand. Or upgrade the mount with motors and invest in a shorter focal length scope (up to about the ed80). A Bahtinov mask must be large enough to cover the aperture of the scope.

Yes, dark skies really are something else. When I moved to a dark(-ish) area, I remembered the very dark nights we enjoyed when I was young. Unlike in Sweden where street lights are on all night, in Holland at that time, streetlights were turned off at midnight and not many people had porch lights. Even in the middle of a village, nights were truly dark. As for star alignment under dark skies. I usually start with sighting along the ota. Then I use the finder scope and finally a low power eyepiece for the first and second star in a 3 star goto alignment. On the second go, I use a higher power eyepiece. This works even when a large number of stars obscure the view. 😉

Besides the Canon, there are two investments you should make 1. A Bahtinov mask to aid in focusing 2. https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html You will also need image processing software DSS, deep sky stacker for preprocessing and the Gimp for post processing, are both freeware. There are also several commercial packages available that offer (time limited) trial versions. Btw, I assume that your mount is the tracking version of the eq3. For any serious astrophotography you need to be able to track the stars movement across the night sky. Good luck and have fun

The dslr is in your signature, so I assumed you had used your Canon camera. If you have the possibility to collect Ha, you'll see it makes all the difference with this galaxy.

The exposure time isn't the only variable in this equation. Sky quality and light pollution matter also. If you have lp from street lights, RGB filters can help you decrease its impact, because most filters are designed to block lp wavelengths. Luminance filters let anything through. If you can image lum at 120 seconds without overexposing the stars, you can safely increase the exposure time for rgb to get better snr. L 4 x 120 s RGB 1 x 240 s each or even 1 x 300 s each Shoot RGB until you can extract a colourful image from the data. Shoot L on nights with clear and stable skies to get as much detail as possible.

Great image, Stu. This galaxy has a beautiful distribution of Ha regions, but with your unmodded dslr these will be difficult to pull out of the data. With more subs you can stretch and saturate more aggressively and reveal a little more colour. Otoh, if you use the cooled qhy you may have more luck.

While it is possible to use rescaling, that may also change the blackpoint of the resulting image. Imo, any call for help runs the risk of this kind of discussions. That's just the nature of the beast (more animal analogies).

Yes, but why simplify things? 😋 mean(original, copy) also works. It seems we need more proverbial felines to skin.

LHE: local histogram equalisation, is a process in the Intensity Transformations menu. I used it with Kernel Radius 240, and amount 0.35. Blending images: Use PixelMath: (Original + Copy)/2 Crop: Dynamic Crop under the Geometry menu, so is Resample (set to 50%) You should also revisit your DBE step. There is still some vignetting in your image, and a dark ring around the main nebula. I used DBE with Division as the correction method, and only about 12 sample points: one in each corner, one somewhat inwards from each corner. Finally a few samples along the edges. Tolerance was 3 or 5 and sample size 25.

Late to the party, but here's my result with PixInsight DBE to remove vignetting Background Neutralisation Photometric Colour Calibration (G2V star as white reference) Arcsinh stretch in two stages Curves transformation LHE on a copy Blending the original and the copy crop and resample to 50% (Click on the image to enlarge.) The core is definitely not burnt out, but I kept it quite bright to get a more natural look (whatever that is). Because of the dust bunnies, I didn't push the dust in the background to its limit.

On paper, yes. In real life, not so easy. The faster your optics are (lower f-number), the more critical everything becomes. The light cone at f/2 is so steep that focus becomes super critical. So does squareness of the focuser. Any slight misalignment or tilt will show in your images. If low f-numbers were so simple, we'd all be using them. You may be swapping imaging time for tinkering time. I recommend that you at least do some research before you go that route. Personally, I find f/5 or f/4 fast enough. I like tinkering, but I also want to enjoy the few clear nights we have.

Stunning indeed. Is that ERE in the background?

There is a script for that in Scripts - utilities: HSVrepair. Just run with standard settings, but also with the "unrepaired V" box checked. Then create a new image from the H, S, and unrepaired V channels. Do this on the unstretched image.

Much improved with better stars and a flat background. To lift the outer ring while keeping the core, you can try starting with masked stretch in PI. Repair the star cores of bright stars before you stretch. Use HDR processes or local histogram adjustments (lhe) to tame the core. In general, hdr will change local contrast by a general darkening of an area, while lhe will brighten the image locally.