ONIKKINEN

I briefly took part in a collaborative effort last spring and found out that its really not my thing even though my contribution was not much more than sharing data that i had already captured. Had no real motivation to process the shared stacks in the end because it really wasn't my own data, even if that stack is the best data i will most likely ever get to touch again. Maybe someone can relate, maybe not. In any case, the process for that project was that everyone shared calibrated data (16-bit for RGB, 32-bit for Ha, for space saving reasons) in a shared google drive folder from which the person who was responsible for stacking got all the raw data. If i recall correctly the stacking and processing part took several days worth of work because there was just so much to go through (i think a few hundred GB, of which 70gb was mine because of short subs). Sharing data this way is not too difficult from a convenience point of view, since everyone gets 15gb of free google drive space to use and you can just delete the data from your drive once the stacker lets you know they grabbed the data. Obviously this method requires that everyone participating has good upload speeds and an uncapped data plan, but it gets the best image out of the input data unlike just stacking masters which is less efficient than stacking each sub to one master.

Also remember to tick the autostretch button next to the histogram, its the lightning bolt looking symbol. That way you can see something other than black and maybe be able to find the Moon by following the glare it produces when nearby. You also need to see stars when focusing, and with the autostretch option ticked you should see out of focus stars as large disks and then be able to find focus.

Teleskop express is very good, as is Astroshop. Both have oddly high pricing for certain items sometimes, so best to look from many sites before purchase. For pricing FLO is actually still very much competitive with EU suppliers even when i have to pay 24% Finnish VAT + 4.2% when importing (4.2% is EU wide, i think). Not worth it for every item but one shouldnt overlook FLO as an EU customer. My last (think it was) purchase from FLO was the Paracorr for my newt, which was 50-150€ cheaper than EU suppliers even with all the "extra" fees.

Without guiding, not really. But my reasoning here is that a beginner will have their hands full learning the ropes for a good while, and the first few images will probably suck anyway (i know mine did, still do sometimes) so the lack of guiding is at first just one of many things to improve on. For a camera we are at a budget where compromises have to be made. Second hand DSLRs are quite cheap and will get an image of a DSO, even if dedicated astro cams are much better. If they got a 120MM for guiding they could also this for lunar, so little money wasted in the end. Vlaiv made a good estimate on a starter set above, which is a bit over budget but substitute the 533 to a DSLR and its not so bad. The Quattro 6 might be a decent option just because it comes with a coma corrector, although its probably not the best lunar scope.

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.