The Lazy Astronomer

If it were me, I'd want to eliminate the hub as a possible issue. Granted it would be really weird if the hub was somehow causing an issue in NINA but not APT, but still good to check anyway.

If it works fine with APT, then it sounds more like a software issue. Assume you're using ASCOM drivers? What are your settings? Are you going through a USB hub? Does the mount always appear on the same COM port in device manager?

Bloating in the blue channel is likey caused by unfocused deep blue and/or UV light. There are ways to reduce it in post, but my preferred option is to correct it at capture by using a filter which cuts the lower part of the spectrum. The Astronomik L3 filter worked well for me. That's really nice image you've got so far though, I'd be well pleased with it. What's your equipment and capture details?

The eq6r is a fairly hefty mount, but that absolute beast of a scope makes the mount look tiny!!

I too am waiting for my Esprit 100 (ordered back in early Feb, hopefully arriving in the next few weeks). Sounds like we will have very similar setups, except I've got the eq6r pro, so we could trade guiding performance figures in a few months to see if it's worth you upgrading.

Concur with all advice given here. Bought a new mount last year, and was originally looking at heq5, but decided to take the "buy once, cry once" stance and got an eq6r pro, which hopefully l will never need to upgrade from... ...said every astrophotographer ever, right before buying an even more expensive mount!

First attempt at M51 with a tiny little 50mm scope. HaLRGB with ZWO294MM @ 2.31um pixel size. Data was very noisy, and looking at it now, the star colours don't seem right to me either, so may try binning and reprocessing on a cloudy night next week. Thoughts and comments welcome ☺

I have the same problem with Startools, but I've seen Ivo get good backgrounds from other people's data, so I'm convinced I just need to find the right settings to get it to work well. Pixinsight is recognised as one of the best stackers though; I'm yet to try it myself, but l hear it's worth the cost for the stacking ability alone. Plus, from other responses here it sounds like you don't actually need a high end PC for it.

Your issue sounds like DSS hasn't found enough stars to stack the frames. It needs a minimum of 8 stars common to all frames in order to align them. Try lowering the star detection threshold and/or trying to stack without any calibration frames (in case those are introducing more problems than they are solving). As a side note, don't do darks with a DSLR, dither between lights and use bias frames - darks are only of use if you can control sensor temperature (i.e. with a cooler)

Not to tell you how to spend your money, but rather drop anywhere from £1k to £5k+ on high spec new PC components* (plus the £200ish on Pixinsight), stick with what you've got and focus on learning how to get the most out of the software on your images. Startools, for example, is very simple to begin using but (as with most things) to get the best out of it you really need to learn what it's doing and how to find the optimum settings for your data. *seriously, the ryzen threadripper CPUs that always top the pixinsight benchmarks are ~£3.5k alone!!

What method are you using to stack the lights? I usually have a couple of subs with satellite trails and the kappa-sigma clipping method gets rid of them nicely with the default values

I will caveat what I'm about to say by saying I've never actually looked at my darks (naughty, l know!), but I think a dark frame should be as you describe: pretty much completely black with a smattering of hot pixels (and amp glow, if your camera is affected by it). Flat frames should be a nice uniform grey.

Hi and welcome to the forum. What is it you're looking to do: solar, lunar, planetary, and/or DSO?

There was a thread on this recently which I think should have all the answers you need:

DSS needs a minimum of 8 stars which are common to all frames in order to align and stack them. I.e. it could find 1000 stars in each sub, but if it can't find 8 which they share, it won't stack them. Also, I can see some coma in the edges (a optical aberration which is common with newts) - this is distorting star shapes to the point where DSS is unable to recognise them as stars. Possibly a coma corrector is required.

Definitely will need a dew shield for an SCT. Corrector plates are like a magnet for the stuff. Frankly, with the rate they seem to attract moisture, I'm surprised you don't see people using them as observatory dehumidifiers...

Dust for sure. They should be completely corrected out with flats. As for the location of the particles, FLO have just released a tool for working that out: https://astronomy.tools/calculators/dust_reflection_calculator

To help with your processing, Ivo (Startools developer) is usually happy to process your data as a teaching exercise if you contact him (certainly, I've seen many posts on the Startools forum where he has done so).

Yes, that is what I meant - judging from this, I would be surprised if there were 300 actual stars in the frame, so I'm sticking with my previous theory. Edit: removed irrelevant statement

What does a stretched single sub look like? Can you visually see a very large number of stars? Maybe DSS is mistaking hot pixels or some other kind of noise for stars and that's messing with the registration and alignment. After registration, you can click the edit stars icon (I think it's on the lower right hand side of the image on screen) and check what it has identified as a star within the frame. It only needs a minimum of 8 stars shared between all subs to align and stack, so maybe as a quick test, re-register the images with a higher detection threshold and see what it spits out (possibly try for around 20 - 50 stars, depending on how significant the drift is across the whole set).

Another NINA user here. A have a semi-remote setup at the moment, in that once I get everything aligned and a sequence programmed I walk away and let it do it's thing, meridian flip and all. Usually quickly rotate the mount around a bit when setting up to make sure there's plenty of slack in the cables so the mount can go wherever it wants without issue. Only fairly recently moved to new area, so haven't quite built up the courage to leave everything out while I sleep, but garden's pretty secure so would be fine, I'm sure. Going to be implementing guiding and remote access to the scope-side PC in the next couple of months, so once polar aligned I can do the rest indoors - I get cold very quickly in the winter just sat at a laptop when setting up! (soft southerner 😁)

Assuming ISO on DSLRs behaves the same as the gain value on astro cams, then the video is right: sensor read noise decreases with increasing gain. However, sensor read noise is not the only source of noise when imaging. The actual image grain/noise does increase, because at high ISO/gain you are not capturing any more photons, just amplifying the signal more, and in amplifying that signal you are also amplifying any noise associated with it as well. That is my understanding anyway, happy for someone much more knowledgeable than me to come along and tell me I'm an idiot and don't know what I'm talking about! 😁

A suggestion for a slightly different direction: the 294MM has the option of either native 4.63um pixels (same as 294MC) or in "unlocked" mode, 2.31um pixels - this would allow you to choose pixel size for desired sampling rate. Obviously you'd have to also get filters and a wheel/drawer for colour imaging, but something to think about maybe.

I don't use SIRIL, but I assume it has a similar functionality to DSS, and if so, it should be possible to stack lights from multiple nights together provided the framing and camera orientation are not too different. In DSS, this is done through use of groups to keep sets of lights and calibration frames associated with each other during stacking - does SIRIL have any feature like this? Edit: great image by the way 👍

Basic rules of supply and demand apply. Supply of new stock is non-existent for a lot of items, plus manufacturers have put prices up (some significantly so), therefore the used market is in a strong position and can command higher prices than has been usual in the past. Ethically, no one should be taking advantage of the recent price rise to make a profit on gear they bought pre price rise, but ultimately a fair price is whatever a willing buyer agrees to.