ONIKKINEN

Very nice, although cant help but notice that your stars on the left side of the image are teal/green?

The focus shift you will experience in any given night will be something like 0.1-0.2mm at worst (for an aluminium tube, less of an issue with anything else) so you can ignore focus position with flats as long as you dont go ahead and have the focuser be at some completely out of focus position. The flat panel in front of the scope is like a kilometer off focus so the tiny little movement at the back of the focuser is of no concern to the flats. I focus manually so cant tell what the right way to set up in software is, but i keep an eye on HFR readings during the first couple of hours of imaging. During that time i typically re-focus maybe 3 or 4 times as the scope is still cooling down from being stored indoors but after that focus typically stays more or less put and i dont need to babysit it anymore. If the night gets much colder, lets say by at least 5c, i might need to refocus well after the scope has cooled down. HFR numbers will tell you that, maybe set up a refocus call in whatever software you use when HFR has drifted by a certain amount? I know NINA can do this at least.

Regarding the barlow and bin thing reintroducing pixelation, you are exactly right. But actually its much worse now since the subs have much lower SNR before the bin happens, so binning back to the no-barlow resolution has only negatives. For fainter and smaller objects there is unfortunately no fast-lane to overtake the issues. Just need more time or a bigger scope, or both if the object is so faint. Binning improves SNR so you get a better image faster, but of course the image is now smaller. The most difficult thing to do in all of astrophotography (including EEVA i suppose) is to get a highly detailed and large dimensioned image of a faint distant target!

Not sure what to say if you dont want to believe me, but this is not correct at all regarding binning. Sum binning and average binning results in the exact same SNR improvement and you are not getting anything more out of sum binning here, you are just getting a brighter image with no extra benefit in it the same way as if you just multiplied all pixels values by 4x (with 2x2 bin). I am guessing autostretch does not stretch the image further if you average bin because there is no point (low SNR). Actually this mention of a barlow sheds some light to the issue. You are using a very small pixel camera, very short exposures and now a barlow lens that turns the scope into a very slow one, no wonder you have hot pixels - there is hardly any other signal going on at F/12 with 4s exposures! Here is what i suggest, not strictly a direct fix to your hot pixel dilemma but will help your EEVA adventures immensely: Drop the barlow, only use it for lunar and planetary. You are really killing the efficiency of your system here with using that and there is no way for me to get this point across too urgently! I am 99% sure you get no extra actual detail with the barlow and its just pure oversampling - which results in a pure loss of SNR with no extra gain whatsoever but it gets you the closer view you wanted. Here is an easier method that does not sacrifice SNR and maybe you dont need to bin (as much, probably still want to): Set the capture area to be smaller around the object you are observing, its as simple as that really. Now the view is zoomed in, you are still at F/5 so the 4s exposures are given a much better chance at success and since you were oversampling with the barlow you actually have the exact same amount of detail in the image! No negatives this way.

I think you kind of missed the point with signal here. How bright the image appears is surely of no concern if it contains no extra information? After all if you were after signal only you would put the camera to the maximum gain it can go and get a very bright image. With average binning the same signal to noise ratio improvement happens than with sum binning, the image just doesn't get brighter, but you can extract more information out of it by applying a harder stretch - which sharpcap should do for you if you click the autostretch button in the histogram. Its possible you get nothing more out of it if the SNR gain is so little but this also applies to the brightened addition binned image. By the way binning with CMOS cameras does not allow you to get away with shorter exposures as read noise gets "read" from the individual pixels whether you bin or not. But of course whatever little positive SNR you have from a short exposure will be multiplied by the bin factor, so it is still very useful if you are oversampling and the extra resolution is of no value to the observations - just not something you can rely on to make very short exposures be much better.

I would be interested to learn just how exactly does the binning happen on camera with the software you use. If it does debayering first to reach 1x and then bins to the desired value there will have been interpolation done on the raw frame. Debayering algorithms have a habit of turning single hot pixels into larger hot pixels, because the debayering process is just a guess on what colours should go in the blank spaces between pixels so there are mistakes (normal imaging employs dithering, so not an issue) Superpixel debayering, if an option, bins x2 and has no interpolation issues. Not debayering and binning results in a mono image, because the data from OSC cameras is really mono. On light grasp of binned images, no difference in addition and averaging methods because its not the signal you are after but the signal to noise ratio.

Dew shield? Never had dew or frost on the secondary in almost exclusively +90% humidity and between -25 and +15 with a dew shield. Dew everywhere else sure but on the mirror, never. Seems counterintuitive to heat the inside of the tube since tube currents with rising thermals are one of the issues newtonians want to avoid if sharpness is at all important.

Simple, easy to use, and astrophotography processing does not go together. You will have to compromise a little bit here, but not compromising on the astrophotography processing part will get you a headstart in learning to process astrophotographs that are very different from "normal" photographs. Try Siril, a free astrophotography processing software: https://siril.org/ Its free and relatively simple to learn. Fights toe to toe with paid software in terms of what it can do and certainly for a beginner will be the least uphill-battle kind of deal because the most important tools in it make processing a breeze. At first i would suggest ignoring everything but 3 tools in it, the background extraction tool, the color calibration tool and the histogram transformation tool.

The method of taking the flats you mentioned sounds ok to me. Only thing to make sure is that there is no screen flicker with the laptop (probably not a problem) and if there is the exposure needs to be long enough to even the flicker out but you can just add more interlayers with t-shirts or printer paper or something like that in that case (if the screen flickers try to make the automatic exposure at least 1/2s, that should even everything out). The mechanical accuracy and stability of everything between the lens cell and the camera sensor are what make or break flats, and just looking at the scope i would assume the focuser to be the weak link here. If the focuser can wobble from one side of the sky to the next it also means the vignetting profile changes, so flats become impossible to match to lights. Its a problem even with good scopes sometimes, the focuser really needs to be much better than just ok to be reliable for astrophotography so this might not be something you can fix easily. Looks like it might have a tension adjuster? If it does, tension it so that you can only barely move the focuser in and out to make it more stable.

No flats could work better than badly working flats, try without the flats? Also you will need to crop the image to a size that is inside the ring this way but you may have needed to do that anyway because of the field curvature (also the image is slightly out of focus on the red channel and completely out of focus on the green/blue channel because of chromatic aberration but not much you could do about this)

2 main reasons for the ring. The first is that you are using a 1.25'' filter with an APS-C sized camera, so there is severe vignetting. You need bigger filters for APS-C sized chips to get less vignetting. The second, and what is the bigger issue here, is that your flats have not worked. Looks like dust donuts are still visible so flats are not working, and the ring artifact would be also gone had flats worked. How did you take the flats? Did you take them immediately after imaging, or better yet during imaging without first moving the camera or touching anything on the scope in any way. And also, how is the focuser on the scope, if it cant keep the camera sturdily in all orientations you will never have proper flats.

And a scruffy mount in general. If the axis are sticky, or the system is not balanced (such as because the axis are sticky), or there is excessive backlash or some other mechanical gremlin then settling will take a while. My AZ-EQ6 has some gremlins in it and so the dither spike always appears.

Do you have solar filtering over the aperture? Specifically something that is designed to work with the large aperture (for solar 190mm is gigantic).

If you set settle time to 0 you will have a trailed frame aftet every dither, so in this case every frame because it takes a while for guiding to lock on again. I would advice to increase settle time to at least 30s. I use 40s and settling still fails about 70% of the time. Increasing the settling tolerance somehow would probably fix it but have not found where to do that, or have bothered to try and find that really.

You are joking, right??

I bought this one, but from the German version of amazon: https://www.amazon.co.uk/AGPTEK-Brightness-Animation-Designing-Stencilling/dp/B0771J6JY4/ref=sr_1_12?keywords=agptek+a4+led+tracing+light+pad&qid=1675896144&sprefix=agptek+a4+trac%2Caps%2C92&sr=8-12 It doesn't look exactly like in the advert, and mine wasn't new even though they sell it as new, i am pretty sure many of the adverts you see in Amazon are actually the same product with a different label and you might not get the exact one shown in the images. You get what you pay for in a 20 pound plastic toy but for taking flats its perfectly adequate. The light is a little bit on the blue side, but that also does not matter too much.

A4 sized LED tracing panel? Very cheap and will cover the 165mm dew shield for sure.

Sounds like you are adjusting it right. Have you loosened the 2 screws holding the worm carrier bit to the mount housing? I mean the 2 in the bottom and not the 2 on both sides of the tiny setscrew. Those should not be overly tight, but also not quite finger loose to allow the worm to move in and out and not be fixed conpletely. In my EQM35 which is very similarly built (backlash adjustment looks identical) i got RA backlash down to maybe 5 seconds but not much better than that because like yours it starts binding. There needs to be a bit of backlash left as the innards start to bind well before its completely bound if you try to make it perfect. Yours could just be like this. Check the gearbox too? The little gears connecting the worm to the stepper motor can be tilted cause extra friction. The up and right trick might be enough for the troubles to go away though.

This is a bit of a problem. You need to always finish manual movements with the handcontroller by moving up and right. You need to first slew the star so that it sits to the bottom left, or wherever the left and down buttons take you (since the image can be inverted, flipped and all that) and only then center the star with the up and right buttons (and only those buttons, you go too far and you start again). This clears backlash and makes synscan work more accurately. I take it you have not read the manual, as this is what you would find in it.😉 But also if that 10s length at sidereal rate is actually so long and not a guess its a problem and you are nowhere near a well set worm but then there would not be backlash as its so loose. Are you sure you are adjusting the correct thing here?

On a phone screen in a well lit room looks a little bit dark, but not by a lot. Nice shot anyway!

If you put too much grease it will just get pushed out as the worm goes through all of the RA gear, so i would not worry about that. Unless you have some absurd mountain of grease in there that jams up everything but i doubt that. But more importantly why are you trying to set the RA axis backlash to be as tight as possible? The axis is constantly under tension so backlash does not matter. For guiding purposes a guide impulse is really just a speed up or a speed down of the worm, but it never really reverses rotation so backlash shouldnt be an issue (unless your guide rate is above 1.0x, in which case you should lower it).

How do the actual subs fare compared to previous guiding? That is the important part, not the prettiness of your guide graph. OAG guiding can look much worse than guidescope guiding because the guider is able to work more accurately - so report and attempt to fix more of the errors resulting in a seismograph. If your average FWHM values have gone down but guiding is worse, guiding is actually doing a better job. Other than that, take 3s exposures or longer with an OAG. If the seeing is really bad you might want to increase to 4s or even 5s. The guide log will reveal anything there is to reveal if you find it.

Beautiful image, rare to see detail as good as you have here. If only good seeing weren't so rare!

Give it a few years and nobody remembers what the issue with AI tools was anymore. I think a large part of the resistance to these tools and BXT in particular is how expensive they are so a lot of people will conveniently choose to be against them when they dont want to dish out 400€ to use them. Which is understandable because that's a mountain of money to most, but still kind of lame to think in the way that "i cant have it so i dont like you having it either". Im going to be honest i used to think that way about many things, but there is no benefit to thinking like this so i just stopped. 400€ in astrophotography is pennies in the end when you think about it... Kind of sad, but its an expensive hobby.

Looks like you got the hang of it already, not much to complain about. Maybe one thing, looks like you NoiseXTd the starless layer a bit too much, or BlurXTd the stars a bit too much. Either way the nebulosity looks a little bit soft compared to star sizes so the nebulosity could use some sharpening, or just a reduction in image size by binning x2. Most apparent in the first image where the difference between the sharp and very tastefully done stars and the soft nebulosity is easy to see.