imakebeer

Venus, Mercury & Regulus, with Mars and the back end of Leo a little higher and to the right 👍 (Clearer skies here than at home but constellations like Leo are at a very different orientation!)

@FunkyKoval35 @carastro I think there's a danger (and it's by no means restricted to you, this thread of even this forum) in discouraging newcomers by telling them that they must have this gear or that gear - the inference is that there's no point even trying unless you have some mega-expensive setup, which is a real shame as it's demonstrably not true and there's still a lot of fun to be had even with basic equipment. Are tracking mounts and guiding good? Absolutely. Are longer exposures better? At reducing read noise, yes, but bear in mind there are also other sources of noise to contend with. Some of these can be mitigated by stacking multiple images, hence my argument for the importance of total integration time rather than individual exposure length. This doesn't make sense. Firstly the definition of a long or short exposure is totally arbitrary. Secondly the greater the total integration time (however you do it) the more photons can hit the sensor hence total signal must also be increased, no? My advice for the OP is simply not to be discouraged if you don't yet have all the gear one might desire, but rather to work with what you've got and above all have fun! The flip side is you need to keep your expectations in check and understand that there are good technical reasons why your images might be noisier than others you see - accept these limitations and work within them. Along the way there are plenty of valuable lessons to be learned on the post-processing side (e.g. when working with limited/noisy data don't get greedy with the histogram stretch!) which will stand you in good stead as and when you're able to upgrade.

@Charming Potato I'm still new to AP only having started in Oct 2022 so feel free to take this with a large pinch of salt, but I have a slightly different view..... When I was starting out I asked for advice which you can read in this thread here..... To sum up, I don't think you need longer individual light frames - what you need is longer TOTAL integration time, i.e. the TOTAL time the shutter is open, summed up over ALL your exposures (as well as light frames you'll also need to take a smaller number of dark, bias and flat frames, explained here http://deepskystacker.free.fr/english/faq.htm ) To a first approximation at least, and as far as I've understood it, whether you do 1 x 600s exposure or 600 x 1s exposures it doesn't really matter. Longer exposures save disk space, but it's 2023 not 1993 and storage is cheap. I do have a tracking mount now but so far I'm still only using 60s exposures. A tracking mount is desirable, but no reason you shouldn't continue to work with the gear you already have and improve on your current (and not bad at all!) image while you consider upgrades. For one thing there's plenty you can learn about the post-processing side along the way. However, one thing a static mount won't deal with is field rotation, i.e. your target appears to rotate as it moves across the sky. To some degree your stacking software might be able to deal with this. I started off with a Nikon D5500 + 18-300mm Nikkor zoom lens, all mounted on my wobbly 20 quid Amazon tripod, and using a manual remote shutter release. I think I was using a FL around 100-200mm, individual exposures up to about 5s long and ISO 1000. Since my tripod doesn't track I recall nudging it round every so often to keep my target centred in the view! I had another play along these lines just recently actually, wide angle at 18mm FL, ISO 400 and 15s exposures. You can certainly use the 500 rule as a guide, but it is just a guide. You'll need to experiment in practice to figure out what exposure length you can get away with in practice for a given FL. Once you've done that you can play around with the ISO to get the histogram in the right place - you want the peak around 1/4 to 1/3 of the way from the left hand end. As long as it's not bunched up all the way to the left (or right) then you should have enough wiggle room left when it comes to post-processing in GIMP. Remember higher ISO = more noise so lower ISO is better in this regard. Something else useful is having something to control your camera to take all these multiple pictures. Your Nikon might have something built-in - mine does but it seems a bit hit and miss. An alternative is a programmable intervalometer remote shutter release, or a laptop running some software such as BackYard Nikon. At minimum you need someway to trigger the camera without touching it, otherwise it'll wobble. For stacking, you mentioned DSS - I've never used it but it seems popular. Siril is also free and very powerful but as long as you have light, dark, bias and flat frames it's quite easy to use the pre-supplied script for stacking and then follow the tutorial and do some initial post-processing. For further tweaking, you mentioned GIMP - I haven't needed to go much beyond this yet. I found this video very helpful to get me started:

We can't see your pictures (or at least, I can't). Better to save them as a *.jpg then you can add them directly to your post here rather than linking to Dropbox 👍

I tried imaging M51 back in April but got distracted during setup and forgot to check the focus so I ended up with several hours with of nearly-in-focus-but-definitely-out-of-focus data! 😭😭😭 I was discussing in another thread with @vlaiv and @ONIKKINEN about astronomical twilight etc. Although it's late in the season I couldn't pass up the opportunity to make amends with M51. If nothing else it's more data to practice with. I actually managed 2 nights, 20th & 22nd May. This is just from 22nd - I'm still working on how to combine the two and get something I'm happy with and that's better than just this one alone. I'm quite pleased with the outcome - I really haven't done much besides basic processing in Siril and very modest curve stretching in GIMP. Also I've tried to respect the limited data I have and not push the stretching too far. I have another image where I didn't push the stars quite so much, but I think I prefer this one - hopefully I haven't overcooked them! SW150PDS + Canon 450D (modified) ~180 x 60s lights @ ISO 400 +10 each darks, biases & flats

Thanks very much for those suggestions @ONIKKINEN . Hopefully I can find some time one evening this week to give them a go 🤞

@vlaiv @ONIKKINEN many thanks for the comments, much appreciated 👍 @vlaiv Exactly as you say, it's not the best time of year to be doing it, I knew this at the outset but I couldn't let another opportunity go to waste - if nothing else it's more days to practice with, and at first glance looks not too bad at all by my standards. @ONIKKINEN At the moment I'm still just using the pre-supplied scripts in Siril to do the stacking etc. , along with one of the basic tutorials for some initial post-processing before moving over to GIMP - so I haven't discovered the features you mention yet. But I'm aware there's a lot more to Siril than what I'm using so far and I'd like to dig deeper - something to keep me out of mischief in the lighter months perhaps!

Thanks @vlaiv 👍 Explaining it in terms of light pollution and SNR it makes perfect sense 😁

N.B. I'm using Siril for stacking etc I left my gear out last night, taking some pics of M51 (fingers crossed!). I set it to take lots of light frames knowing full well that dawn would soon come and the later ones would end up being scrapped. But what about those last few frames where you can see the day light starting to creep in? How can I decide which frames to stack and which ones to exclude? Or do I just throw them all in and then will Siril automatically decide what it can/can't use? Three examples (unprocessed JPEGS!) below from 0300, 0330 & 0400hrs: Thanks in advance 👍🔭😉 0300hrs 0330hrs 0400hrs

Thanks for the tips @tooth_dr and @Lee_P , much appreciated. I understand what you're saying about the benefits of a cooled astrocam w.r.t. noise - it's obvious now you say it! I have more software on the list to trial, just need to find a relatively clear stretch when I can play before I press "go" on a 30 day trial.

Fantastic image @Lee_P 👍 By coincidence I just posted yesterday my latest M81 / M82 pic, taken from a Bortle 5 area. I'm pleased with the progress I'm making but I'm still some way behind your effort. Can some of you experts help explain where the differences are coming from, and what changes might deliver the most bang for buck? E.g. Integration time: 20hrs vs. 2.5hrs. This I can fix for free, with a bit of dedication on my part and maybe a bit of luck with clear skies. Camera: ZWO ASI 2600MC-PRO vs. modified Canon 450D. I think both are OSC (right?). The ZWO has a slightly bigger sensor but not than double the pixels, and small pixels at that. But does this mean a big difference in images vs. the difference in cost? Scope: Large diameter ED refractor vs. low cost reflector (SW150PDS in my case)? Again, there's a big difference in cost but does this necessarily translate into a big difference in images quality? Post processing: I can practice for free. And Siril and GIMP certainly don't seem bad for free software, but maybe paid for software like PI and the various xXterminator tools offer that little bit more??? Thanks in advance for any tips you guys can offer 👍🔭

I haven't posted in ages as life and work keep getting in the way (along with clouds and nightfall coming later and later!) Since I started back in October 2022 I've been using a Nikon D5500 but during my early enthusiasm I picked up a used Canon 450D from eBay, which I finally sent away for astro-modification a couple of months ago. These pics are from 2nd April 2023 - I decided to stick with something "known" and "easy" (hah!) for the first test drive of the 450D. Capturing was striaghtforward enough but I've been playing when time allows, continuing to improve my post processing skills. I had already discovered Starnet, and the new beta of Siril not only uses this to remove the stars but gives you a star mask too. I'd already started playing with layers and masks in GIMP but inspired by some Doug German post-processing videos on YouTube (he uses PS, not GIMP) I've been playing with smarter(?) ways to recombine layers to control the stars, and also reduce noise and light casts (?) in the farfield - rather than just using layer masks and playing with the opacity of the star layer I've also been playing with the Layers "Mode", experimenting with different ways of bringing the layers together. Anyhoo..... SW150PDS + HEQ5 Modded Canon 450D + SW coma corrector 150 x 60s lights @ ISO 400 + 20 each darks, biases & flats Siril, Starnet and GIMP Compared with my previous (and only) attempt at M81/M82 (02/03/2023) I feel it's improved - I think I've done a better job of controlling noise in the farfield and I feel like I'm bringing out more of the detail of the "tiny" stars in M81. The first image is what I got out of GIMP. The second image is the same but I ran it through Neat Image v9 to reduce noise (automatic/default settings). It's done an OK job but lost some of the detail (tiny/faint stars in particular) so I'm not sure it's better. Somehow, somewhere I need to pony up and pay for a better NR software (I trialled Topaz DeNoise AI which did a better job I think). GIMP Image GIMP + Neat Image v9 (noise reduced)

I would say using it mostly for imaging - I don't want to completely give up on visual hence I want to keep the visual finder scope ideally (plus I can see it being a useful backup). I thought about doing as you say, attaching the dovetail to the 150pds rings, then attach the guidescope rings to the dovetail. The issue here is that the bolts for the guidescope rings are smaller diameter than the holes in the 150pds rings and the dovetail so there is potential for some play.

Since the weather at the moment seems to be terminally cloudy I've finally turned my thoughts to how to attach a guidescope to my SW150PDS - advice from the SGL massive would be much appreciated..... First pic below shows the OTA. Mounting options seem to be either to attach it via the finder shoe circled in red or piggy back on to the tube rings circled in green. Second pic shows the bits I have: Altair guidescope Tube rings and standoff (?) supplied with the guidescope An alternative black finder shoe (?) A green Skywatcher (?) dovetail (?) Also various bolts I can use but they're cheap if I need more So it's a question of whether I can use what I have or if I'm better to get some other bits? 1) Easiest option seems to be to fit the guidescope into its tube ring assembly and attach that to the existing finder shoe (it fits). But it seems like it might be handy to retain the optical finder scope??? 2) I could replace the stock finder shoe with the rather more sturdy-looking black one. I'm somewhat reluctant to do this for fear of dropping the small nuts down the tube or knocking the secondary mirror but I can probably do it. But I still lose the optical finder scope. 3) I'm given to understand that we want the guidescope to be mounted as rigidly as possible so maybe piggy backing is the much preferred option... I'll need to rotate the OTA in its rings to avoid the focuser - not a problem. I think I can fix the spare green dovetail to the OTA tube rings but then what? I'm not sure I can then easily attach the guidescope tube ring assembly to the dovetail. At least, I can probably attach it but I'm not certain how rigid it would be. So am I better off to source some extra bits for piggy backing, and if so, what? Or do I just take the easy option and see how I get on for now. Thanks in advance 👍

Thanks for the feedback @WolfieGlos. Yeah I switched off the stretching which improved things. I'll let you know about Siril but based on what you've said I'm not too optimistic, but we'll see.