ONIKKINEN

EQ5, PDS130, autoguiding trinkets would fit the budget. Not much left for a camera, but some second hand deals could work for that. I would be inclined to suggest an HEQ5 instead and maybe start with lunar first and some short exposure DSO unguided to get going. Wont be too long until guiding turns out to be necessary but that could be another purchase if the budget doesnt stretch further at the moment. Or alternatively lean more into the DSO use and get a small refractor that can work well with a smaller mount. Something like a redcat51 or an Edph 61 and an Az-GTi. Or a Samyang 135? Many options, all fairly expensive though... Good idea to check what the second hand market has to offer for sure.

You can safely drop the dithering rate to something like once every 20 minutes if you have one of the newer cooled Sony sensor cameras (not sure about others). You will want to calibrate with a bad pixel map in that case, as hot pixels could otherwise remain in the stacked image. Think i recall reading that some imx571 users here dont dither at all and with a BPM it still works out. I also have/had dither settle issues in my AZ-EQ6 because its a little bit stiff, and the solution was to just not dither as much.

Darks need matching temperature, gain, offset, and exposure length. They do not need to be taken in-situ with the telescope and can be reused many times. In fact its better to take them indoors, such as in the fridge to make sure they are taken in perfect darkness. If you meant a DSLR or an uncooled camera its more complicated.

Here is a more convenient solution: a tablet. I use an android tablet to control my mini-pc (with the remote desktop app). Coldest i ever used it in was -27, with the average imaging temperature being somewhere around -3 and typical winter nights going below -10 regularly, and it still works after 3 years of this tech torture. Its not the cold that is the problem, its the condensation when you bring it back to a warm place so try to keep it under some kind of cover when it warms back up. The display is a bit unresponsive out in the cold and can have an input delay of a second or so, but it still works. One major issue is that batteries in these devices do not accept charge when they are too cold (i think below 0c). So you will have to warm it up somehow to charge it in cold weather. Some solutions: put it under your jacket and let your body heat do the work, or sit on it and have your car seat warmer do it. Batteries die pretty damn fast in cold temperatures, so this is not maybe a problem but a guaranteed one.

Yep, looks like hot pixels spaced out by random dithers. Decrease the hot pixel sigma in the integration tab until they go away, try 3 for starters.

Similar thing happened with my 120MM as well, although in the guide log i also saw that SNR and star mass dropped to 0 with no cloud or other obscuring going on. Not seen that with the 220MM i upgraded to.

If we go by the usual blurb of ideal f/ratio= pixel size x5 then this thing would be perfect for a whole bunch of scopes at f/7. Not too bad for f/5 either. I wonder if there is a catch? Price is pretty good too.

Beautiful image, definitely came out well.

Thanks, i did get 6 clear nights in October so i am probably due for at least 3 more cloudy weeks to even the scales.

Looks like walking noise, which is a capture issue and goes away with sufficient dithering. OSC cameras usually have a fixed bias/dark pattern of some kind that usually is seen in the form of horizontal banding. If we dont dither we stack this pattern on top of itself and reinforce this to a point where it can be seen in a stacked and stretched image like i think has happened here. Dithering by a good 10+ pixels every now and then mixes this pattern and it will get either evened out by stacking or just removed by rejection algorithms.

Now im curious, just how much data are you planning on getting? 1000 subs with the 571 is only 50gb, and will be a deep image even with shorter (say 60s) subs. And yeah, i get the aversion to getting more space. I think i am sitting on somewhere around 4-5 terabytes of data (not all of it just raw) for 3 years myself, and because of that the plan is to try and take longer subs to try and not let it get out of hand too much.

Time to invest in new drives i would say, 4TB SSDs are really not too expensive these days and will surely store your raw files for a while. I would recommend storing only the raw data, and not the calibrated (or worse: debayered) files until you are finished with the target and start stacking. For data handling not sure what software you are using but Siril is the king of large datasets. Really nothing else comes close to its speed when calibrating/registering/stacking.

Try lowering the star detection threshold and see what happens?

I use a travel minirouter that creates a dummy wifi network to which i connect to with a tablet using remote desktop. Simple, but works. Never had any weird connectivity issues (other than short range, but not really an issue).

Anecdotal evidence from me, but have also found that imaging just an hour or two from an SQM 21.3 location results in a better image than any single night could (6-8h) from a 19.5-20.5 location. So i find that 6x imaging time required per 2 magnitudes is easy to believe.

If you have everything perfectly aligned the image should flip by 180 degrees, so will have no effect on framing in the end. Often there is cone error and/or polar alignment error so the difference in orientation is not exactly 180, but up to a few degrees below or under. In that case your pre-meridian data and post-meridian data will have a slight rotational difference which can lead to incomplete edges for the image, but typically just a small crop is all that is needed. The closer to the celestial poles you image the worse the effects of cone error become, for example my setup had a rotational difference of 3 degrees pre/post meridian at a declination of 73, but this is on the worse end of the spectrum. In short, usually there are little to no issues with all this.

Looks like chromatic aberration, yeah. Bright stars are larger on the blue channel than the red and green channels, which is seen as star bloat. Probably just the 72ED to blame and not something to do with the camera itself i would say.

Been cloudy for a few weeks now, so gave old data another go for practice. 32-ish hours with an 8'' newtonian, TeleVue Paracorr and a RisingCam IMX571 OSC camera: Made the same mistake (debatable perhaps) as the last times, which is pushing the IFN too far, just cant help myself it seems. If its in the image i fight tooth and nail to get it out when perhaps it should not be so promiment but oh well this is what i conjured up this time. Of the 32 hours around 8 are with the Antlia Triband filter, which i also stacked as a separate image and then overlayed as an extra layer with Photoshops lighten blend mode to boost some of the Ha regions a bit more, so a composite of 2 images in a sense. Then to the main course and why i reprocessed this at all: Globular clusters around M81 annotated with TypeCat and PixInsight, upscaled a fair bit to see the small globulars better. TypeCat found 113 globulars in the image, but i erased some of them especially around the core where they were not easy to see or visible at all, also the image is just a wall of text with all of them. Still an almost unbelievable number of objects that look like just another faint star, but are in reality globulars over 11 million light years away! Thanks for looking, and give TypeCat a try to see how many of these distant globulars are hiding in galaxies nearby! -Oskari

Colour looks good to my eyes too, and detail of course. Nice one! Im curious how much data you rack up per project with one of these since you have 11 panels, must be at least a couple hundred gigabytes?

Advice about guiding has been given, and i fear not taken seriously or considered at all. But anyway i have 2 pieces of camera advice: My first piece of advice would be a guide camera and an OAG or a guide scope. Longer exposures will bring in somewhat more meaningful amounts of Ha even with a DSLR so your friend will get what they want + guiding. I get it, not the answer you wanted but still wanted to say it. As for the advice that doesn't include guiding: 533MC at this price point is a good choice. Good camera, but a little bit small in the sensor size department so with the extreme focal length of the C11 only fairly small targets will fit the chip. Still think this is the go-to for under 1k. That is if something doesn't come up on the used market, in which case anything goes and a good deal could be just behind the corner.

Check this out: If you're into ancient Roman history, this YouTube channel will definitely interest you outside of this one specific question. Goldmine of information really.

Hard not to recommend the 120MM for this purpose. With a 50mm finder/guider you could still be under 300€/$ so for budget applications this would be the setup to go for.

Yep, agree with the above. Guiding is in my opinion not really optional for high resolution work. Would be a good idea to talk to your friend about it and get them to at least look at autoguiding options.

Looks a bit too magenta on my monitor, SCNR green went too far? Very true. Its a weird mix of neutral coloured nebulosity, specks of emission nebulae and resolved stars (in a large scope) with weak colours that sometime just wont come out the way they were intended to. Not to mention the incredibly bright core, tricky target i say.

What coma corrector were you planning on using for the 1.0x comparison scope? For a newtonian this is the most important optical component and will make or break the image. Have not seen too many images with the nexus reducer, and even fewer mentions of star sizes it produces. Would be very interested in seeing some data taken with that thing as i could see myself getting one some day. If you compare the nexus scope to an uncorrected scope, the nexus will win easily in terms if actual resolved detail. If you compared to a quality 1.0x coma corrector, then i would guess the nexus is second even in the bigger scope as reducers are often borrowing detail for speed. Just a hunch of course, as have not seen much of it.