ONIKKINEN

Im having fun experimenting with mosaicing and extreme binning to circumvent the low altitude sharpness issues. At 100% zoom of the original capture resolution it appears as an aberration bingo with a hit on every line, but reduce size to 1/6th and they all go away like magic. An Orion 3x3 mosaic is in the works too but that one was cut short due to arrival of clouds, so couldn't finish even a single run of the sequence but it should also turn out pretty good even if it is a few degrees closer to the horizon.

10x60s in a 2x2 mosaic of the Horsehead and Flame nebulae with an 8'' newtonian, Rising Cam IMX571 OSC camera and an Antlia Triband RGB ultra filter. This target is not really shootable from my latitude of 60N, at least not if one would go for high resolution data. So i binned it x6 to make up for the short integration and the terrible stars you get with 20 degrees of elevation. Seeing was also bad not just towards the horizon but everywhere else, so this was more of a necessity than a pure choice i wanted to make. Processing in PI, Siril and Photoshop. The colour palette is whatever PixInsights SPCC tool made of it when i input the filter information of the Triband RGB (removed a little bit of green afterwards). Applied BlurXT but it has very little effect because the resolution is already quite crunched to 4.5'' per pixel. Did sharpen stars a little bit, and maybe the edge of the horse a bit. Also generous application of NoiseXT to cull the noise a bit. No starless processing for this, didnt see the point as BlurXT fixed stars well and i find there is no need for specific starless processing afterwards.

Any chance that car headlights could sweep the sky just above the scope? If there was a thin layer of fog that is not apparent naked eye it could look like this. I often setup at car parks or slightly off a road and these things happen.

First light of a newly installed Helmerichs carbon tube: Perfect conditions for heavy frost, was above 0 and raining in the afternoon and then plunged to -6 for the night with humidity licking the 100% mark all the way. Also perfect conditions for 3'' fwhm seeing, but beggars cant be choosers so the scope goes out. Its mildly interesting that anything with electronics in it, namely the 2 cameras and the mount, are free of frost while everything else is completely frozen. Almost looks like the clean cameras dont belong in the scene with how dry they are.

Hmm, i do think the 0.47'' version looks better in all of the above comparisons so far to the binned one. Neither are comparable to HST data, but we are not comparing it to HST data are we? At least we shouldn't be. The comparison was between @tomatos 6'' refractor and whether or not BXT worked better with the unbinned or not. The middle one from the bottom row looks sharpest here, agree. But these are not apples to apples comparisons in my opinion as they are different processes so different choices must have been made. Also comparing mono to colour, which hardly has a point since the point is to present a colour image. My eye gravitates towards the colour image here at first, the HST image second and your sharpened version third.

Just stirring the pot a bit and adding some options, if you were looking at a 2600MC or similar camera. (prices are what i could find shipped to UK addresses) Altair, 1400 pounds: https://www.altairastro.com/altair-hypercam-26c-aps-c-colour-tec-astronomy-camera-16bit-6451-p.asp QHY, 1600 pounds: https://www.modernastronomy.com/shop/cameras/cooled-ccd/qhy-cooled-ccd-cameras/qhy268c-photo/ ZWO, 2000 pounds: https://www.firstlightoptics.com/zwo-cameras/zwo-asi-2600mc-pro-usb-30-cooled-colour-camera.html And a wildcard, a RisingCam from AliExpress. This is often the cheapest one and currently at 1121 pounds without VAT so just a tiny little bit cheaper than the currently excellently priced Altair one: https://www.aliexpress.com/item/4001359313736.html?spm=a2g0o.productlist.0.0.6f047164JGhOx6&algo_pvid=88c7fc7f-59b2-4b58-9bdc-a75b08237944&algo_exp_id=88c7fc7f-59b2-4b58-9bdc-a75b08237944-0 Pick your poison, all of these have the same sensor and more or less the same technical specs. Some small changes in drivers and read noise and such but generally you can treat each of these as the same camera when it comes to data that comes out of them.

Fewer pixels so the filesize is smaller naturally. By the way ASI fitsview is not very useful for actual image analysis as it stretches the image with some arbitrary set value so you are not really seeing the raw data. Its better to view the image in something like Siril where you can make objective measurements on the pixel values/standard deviation/whatnot and try to make an educated guess on the sub. But ultimately i dont recommend viewing subs at all, just check their statistics when stacking (and maybe reject the worst ones) and only judge the final stack on quality.

How do you quantify the amount of noise in bin1 vs bin3? If its with a stretched file you should make sure that they have an equal stretch. You should also view both at 100%. Bin3 will have 3x signal to noise ratio or in other words be equal to a bin1 exposure of 9 times the length. It just doesnt make sense (cannot be true) that the bin3 image is noisier.

You are missing nothing, certain brands carry a price premium for many reasons. ZWO has a price premium i suspect because their moneymaker product, the Asiair, locks people to ZWO cameras only so they get away with it. They are also the most popular brand so the name carries weight (think apple and samsung selling kit for 30% more than an equal product for no reason).

ASTAP (free) has a binning tool which works with colour images that you can use after capture. Easiest way is to stack unbinned and bin the stack before making any adjustments. You can also batch bin your subs and then stack them, same result either way (almost).

On top of keeping all the raw data i also keep calibrated subs of work-in-progress targets where i will need several nights worth of data to get it done. Makes it faster to stack everything to test something new or test how an extra night will affect the stack. The only raw data i dont keep is planetary/lunar since it would mean buying a new hard drive every 5 sessions. Have only kept some that are either exceptionally good or exceptionally bad so that i have some references for future.

On the topic of dubious articles, just google "best telescope 2022". Guarantee that you will not find a useful article (nor is the question answerable, but you will not find this information either). This here is the best telescope in the world apparently: https://www.digitalcameraworld.com/buying-guides/best-telescopes-for-astrophotography If you read the incredible work of fiction a little bit you will come up with this: and Anyone who has been within 10m of an astromaster 130 and especially the mount it comes on will be able to tell you that this is complete nonsense.

You forgot about latitude here a little bit. The Moon is often at 10-20 degrees of elevation here at 60N so you could image almost to the opposite side and with a reasonable elevation. Had there been a choice i would have answered more like 120-150 degrees or better said just "as far away as possible without compromise in elevation".

Bias frames can be used as darkflats to calibrate your flats, provided they are roughly in the same temperature and exactly the same offset. I would take a set of darkflats of roughly the same exposure as the flats instead of bias. For lights you will need to take actual darks to properly calibrate out your offset and the (extremely) little dark signal the camera produces. If you are very lazy you could also use bias/darkflat frames as dark frames for short exposures, have done that and not sure there were any issues. But hardly any reason to skip darks as you take them once and forget about it. So im short, darks to calibrate lights and darkflats(or bias) to calibrate flats.

Agree, tilt is excellent. Trying to fix that tilt will make it worse for sure.

I try to image a target that is the most efficient for a given night, so under a significant Moon that means imaging the Moon itself, or one of the bright planets that dont care about the Moon. If the Moon is too low to image and planets are not available (or the seeing is bad) then i will bite the bullet and image something to the far north.

Here is one of my darks taken with a RisingCam IMX571 (same manufacturer as yours), 60x 60s debayered stretched and screenshot in Siril: Looks not too different to yours. The important thing to note here is that it is VERY stretched and the actual differences in intensity are not that big. Sensors are not perfect and you will inevitably have some kind of difference in intensity of different coloured pixels (and possibly a gradient like these) so i wouldn't worry about it. Of course if you have light leaks then retake the darks. You should have the camera off the scope and completely plugged from light in a dark room when taking darks. If you have the camera on the scope the darks will be ruined in most cases unless you have basically perfect darkness at your site. I believe you might have some light leaks as you have a full 1 ADU difference in median pixel values in the green channel between the left and right edges (mine has 0.3ADU). It may also be just that i am comparing a stack to a single frame so might be nothing after all. But, an issue you should fix and it may actually have something to do with this is your offset which is way too low which results in 0 value pixels that carry no value and cannot be used for proper calibration. You should increase offset until no pixel values are at 0 in a bias frame. My camera had a default offset off 768 which is just fine and there was never a reason to touch it. I recommend increasing your offset to at least 500.

GPU doesnt need to be great, basically any modern-ish model should do the trick. I have an aging GTX1080 and its working along nicely, looking at newer models the RTX3050 looks like about the same in benchmark performance and doesn't cost that much so i would go for that. Should you do any gaming it would still be pretty good for that so its certainly not compromise type purhcase. CPU and RAM is where you should try to spend most of the budget. Decent ram, but doesn't need to be some gaming spec with RGB lighting to do the trick. At least 16gb, preferably more. CPUs, too many to choose from at the moment but AMD seems to be making better general purpose CPUs at the moment. Dont underestimate storage needs, you will rack up terabytes much faster than you thought, especially if you have many unfinished work-in-progress projects where you have calibrated data saved on top of the raw stuff. I would go for an M.2 SSD for drive C, another (terabyte or two, not that expensive these days) SSD as a processing folder and maybe a conventional HDD for bulk deep storage of stuff you dont need to access all the time - like data from previous seasons that you may one day use again. HDDs go for quite cheap too, you could get something silly like an 8Tb drive for a couple hunded. Storage is also upgrade-able almost infinitely, so maybe not necessary to splurge on all the different disks at once. Invest in the core parts that stay in the PC like the CPU/RAM/Motherboard at first if budget demands it.

M33 is an easy target to process, once you get enough data to get a meaningful amount of stuff in it. That is the harder part because while the numbers suggest its a bright target it is actually quite diffuse because it occupies such a large area in the sky and so you will need to invest a few hours to get a decent image out of it. But from a processing perspective its quite easy as there is no obvious extreme brightness difference as you have with M31/M42 so you could just simply stretch it and be done with it. M81 and M82 on the same field of view is another great beginner target that is not that difficult to capture or process. Should become shootable in the coming months for most imagers in northern europe. Another one later on in spring would be M101 which is kind of like M33 in terms of imaging difficulty but maybe requiring a little bit more time to finish. Think at least 5h rather than a couple and the more the merrier.

Sea of stars, love to see it. Star clusters and starfields are underrated in the imaging world imo.

Not seeing square stars, but i guess your star shapes can look a bit square-ish with the aberrations around them. Took your .PNG of the stack and turned sharpening to 11 to show starshapes better: Lots of things could be to blame, like collimation if its way off, obstructions to the light path, something in the way causing diffraction (tree branches, powerlines), pinched optics and so on.

All sensors have a maximum capacity of electrons a single pixel can hold, once that limit is reached the pixel is saturated to full white and all further information to that pixel is lost. Increasing ISO will lower full well capacity and read noise. There is a point in which read noise no longer decreases significantly but FWC does, before that point is the right place for the ISO to be (the tables seem to make sense here and yours should probably be used in the recommended range). Dynamic range is the difference between read noise and FWC by the way. But dynamic range of a single exposure is not very important in AP as we stack hundreds of exposures to increase the effective dynamic range so the 1 sub dynamic range is mostly a pointless stat.

First time trying PI yesterday. Hate it so far, but i will cave in and get it just for BlurX to work. I will probably not be doing anything else with PI as its just so unbearably slow at doing anything simple whereas Siril will register, normalize, and stack 2000 subs faster than PI does star analysis on the same set of subs. BlurX flat out improved any linear stack i found on my HDD without any negatives that i found. It makes all the images i tried it on look like they were taken on a bigger scope under stable skies and great guiding (none are true in normal conditions). The future is now and AI is here to stay.

It depends on the sensor used where the ideal range of ISOs is. Sensors usually have a point where increasing ISO decreases full well capacity significantly but no longer reduces read noise as much. At that point its pointless to increase ISO as it will just saturate stars earlier but offer no benefit of significant value. There is also this misconception that DSLR images should have a specific looking histogram or that the subs themselves should look good and show the target clearly. That is not necessary, the only thing deciding whether a sub is long enough is the amount of electrons in it, not the ADUs or histogram shape and placement. You get a brighter image by increasing ISO past the optimal point but it will still have more or less the same SNR as an exposure of the same length with one setting lower of an ISO.

Without a specific budget its difficult to advice. If you can, get an EQ6 and the best scope you can afford after that. If youre writing a website with scope advice it should also be bracketed into budget categories as no one scope can fit all purposes on all budgets. Beginners reading that article should walk away from reading it with the knowledge of mount 1st, mount 2nd, mount 3rd and then maybe start thinking whats left to buy a scope. You can always upgrade a cheap initial beginner doublet for a better scope but a bad mount will be bad forever and only a waste of time and money in the long run. But my 2 cents on a scope that does a bit of everything would be an 8 inch newtonian on an EQ6. Aperture to cost ratio is very good, unlike apochromat refractors (but there is a catch, of course). Will require plenty of elbow grease and/or further investment into upgrades to bring a factory standard newtonian up to demanding imaging spec, but its not something you necessarily have to do right away. For example i have spent maybe 1800€ on upgrading my VX8 with a carbon tube, focuser, secondary spider, corrector, rings and plate, to bring it to astrograph standard. At this price point its comparable in price to triplet apochromats with half the aperture. You could substitute half of what i spent with DIY if needed so the deal only gets better.