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.

Thanks for the feedback Olly, this is helpful. I agree with you - I'll take a look at the histogram and see if I can tweak in a bit more green/less magenta 👍

One thing I always seem to struggle with is noise, particularly in the farfield of my DSO images. I'm not ready to bite the bullet and fork out for software to do this so in the meantime I've been having a play with some free tools. Below is a with/without or before/after comparison of my last M31 capture from January 2023 - stacking and initial processing was done in Siril. @Elp mentioned to me in another thread about trying StarNet to make a starless image. This worked really well and I found it much easier to stretch the histogram in GIMP when dealing with just the galaxy on it's own and so bring out more detail 👍 I added the stars back on a separate later and made them only 25% opaque. I'm pleased with the result as they seem less stark and don't dominate the image so much. Following that I found AstroDenoisePy - maybe paid tools like noiseXTerminator are better but for a freebie and never having used a de-noise tool before it seemed easy enough and did a pretty good job I think. ( @WolfieGlos I saw in another thread you had tried it, I'm interested to get your take on ADnPy) I found it changed the colour quite a lot until I dialled back the de-noise level from the default 0.9 to 0.25. Also I'm not sure if I'm doing these processing steps in the right/best order??? It also looks like the latest beta of Siril had some new de-noise capability so I'll be trying that out too. Anyhow a comparison of the images below. I'm pleased with the outcome of these new techniques, though I've still got loads more to learn and perfect. Any comments, tips or feedback would be most welcome! Original: Siril + GIMP Re-processed: Siril + StarNet + GIMP + AstroDenoisePy

The months have kept rolling by since I started AP last October and old faves like M31 and M33 have disappeared for now, but new targets are coming into view. I got the gear out for the first time in ages the other night. Unfortunately I was a bit rushed setting up because reasons and things went a bit awry and I ended up taking nearly 90 light frames at ISO 25600!!! Not to be deterred I reset and pointed the scope at M81 / M82 and managed to get an hours worth of data before it clouded over. Ideally I'd do double this but it's a start and I'm quite pleased with the outcome as a starting point. SW150PDS + HEQ5 + Nikon D5500 60 x 60s at ISO 400 lights + 20 each darks, biases & lights Processed in Siril and then tweaked in GIMP In GIMP I had another play using layer masks. They seemed to work well on M42 when I tried them recently though I'm not sure if they're the best for galaxies like M81 but I thought I'd have a go. One thing I've struggled with in the past is once I stretch the histogram to bring out the detail it introduces a lot of noise in the farfield. If you look closely around M81 & M82 you can still see this noise but the use of layer masks means it doesn't extend across the whole image. As I say I'm pleased with this one as a starting point and I'm excited to try some new targets, but I really want to get to grips with how to bring out more detail.

@Elp @Vroobel thanks for the advice and suggestions, much appreciated 👍 I'm gonna take a look into modified DSLRs, starting potententially with modifying my 450D myself - need to check out the tutorials for this on YouTube. I'll also take a look at StarNet as this seems like it could be useful more generally anyway from my initial look.

Hey @Elp , can I pick your brains on this a little more... Up the top of this thread @Vroobel has suggested a couple of Optolong filters - they're not cheap but, well, ok... In the course of my googling I found this thread from ~9 months ago in which you said you'd tested the L-Pro, L-Enhance & L-extreme... In your experience do you think any of these would offer an improvement to my Pacman based troubles?

While my Pacman nebula needs more work I'm happy to report I've made much better progress with my M42 First pic below - just for comparison - was an early AP attempt last December while I was taking my first steps (reprocessed slightly when I discovered layer masks recently) Second & third pics are from 5th Feb 2023 - SW150PDS + HEQ5, Nikon D5500, 120 x 60s lights at ISO 400 + 20 each flats, darks & biases. Processed in Siril & GIMP. I made 3 images in Siril with different histogram stretches, then used layers and masks in GIMP to blend them together. I'm super chuffed with the textures in the clouds, looks very ethereal. I want to have another go though - I think I've lost a bit of detail in the dark looking area just below and left of the triangulum, this could be a bit brighter, I just need more practice with the layer tools in GIMP. I think the second pic looks more natural, but in the third one I think I've gone a bit mad with the hue-chroma - what do you folks think?

Thanks, I think that makes sense and I had a feeling this might be part of my issue. I need to understand better the different types of nebula. I also have a Canon 450D I bought cheap off eBay last year when I was getting into AP - I might consider modifying it myself or change it for a modified camera. Not sure I want to do this with the D5500 as it's my main family camera. Main issue with the Canon is being older I think it has a slower processor as it seems to take much longer than the Nikon to take and send and image to the laptop. Meh... storage is cheap 😉 I'm intrigued by these filters. They're not cheap - a 2" L-eXtreme is a significant fraction of the cost of my OTA alone. Not that I started this hobby to save money, but still... The blurb about these filters on the FLO websites implies I can just bung one in - I assume inbetween the focuser and DSLR? - and all will be well with the world. Is it really that simple?

Thanks. As noted in the OP (😉) Siril and GIMP. The former is sometihng I've been recommended by others on here. Sorry, I forgot to mentioned flats in the OP, now corrected - I did 20 flats too. I seem to get diferent areas of lighter/darker "haze" across my images, I suspect there is a lighter patch just out of the frame which might explain what looks like vignetting. I can see vignetting in the original image but then this version has been massively cropped way beyond this. The reasoning behind doing 60s at ISO 400 is this - from what others on here have told me, it's the total integration time that matters most. So whether you do 100x60s or 60x100s or 20x300s it doesn't really matter. Also, since I've not sorted out auto-guiding yet I find if I go above 60s the star trailing becomes unacceptable. Plus, when a satellite goes across your FOV it only ruins one of many shorter frames. Re. ISO, my D5500 is ISO invariant so if I go above ISO 400 it just introduces more noise. Looking at the histogram it seems like there's enough wiggle room there - it's not like the peak is hard up against either end of the scale. Which is not to say it wouldn't be worth trying different camera settings, just when I've tried it on M33 for example it didn't make any noticeable difference. Hmm... OK, interesting... As noted I did flats, just forgot to mention it in the OP. So maybe in part the issue is a stock D5500 just isn't up to the job for this target??? 🤔

I've been making steady progress in the last few months and made steady progress with M31, M33, M42 & M45. So I thought I'd have a go at the NGC281 Pacman Nebula. But I'm really struggling to get much out of it so far - I'm not sure if the problem is simply that it's a really faint target and I just need way more integration time, or if a standard DSLR won't cut it and I need to try a modified/dedicated camera and/or use HOO and/or SHO??? Or maybe the problem is simply light pollution??? I'm in a Bortle 5 - I set the scope up in the back garden away from the streetlights out front, but then my neighbour's landing light is shining down on the scope which really isn't ideal either! SW150PDS + Nikon D5500 126 x 60s lights at ISO 400, plus 20 each darks and bias [EDIT: and 20 flats too!] Processed in Siril then tweaked some more in GIMP. This version is heavily cropped because I wondered if the background extraction in Siril was causing issues, but I'm not sure that's the case. Can anyone offer any pointers? Cheers.

Thanks @ollypenrice , and thanks also for the suggestion👍 In addition to layer masks I think I'd also heard about your technique of different exposure times for areas of different brightness. I suppose the big investment is the longer exposure part to get the faint areas (say, 120 x 60s), but from there it's less investment to do an additional, say, 120 x 10s. My only uncertainty here is you'd end up with 2 different stacks - isn't there a possibility they'd be slightly out of alignment with each other, and so how do you ensure your layers are perfectly aligned? (I'm certain it can be done, I just haven't learned how yet!) I suppose it's no different to challenges you might face if you're collecting data on multiple nights, and possibly even related to the challenge of how to merge together different areas of a mosaic 🤔