KevinPSJ

I struggled with processing my DSLR shots for a long while - could not eliminate noise despite taking plenty of dark frames. Looking on-line here and other forums it seems the recommended approach to reducing noise (walking noise especially) is using dithering. Unfortunately I don't have a goto mount - just RA clock drive. It seemed like this technique was out of my reach.

Both necessity is the mother of invention as they say so I thought I'd at least try and see if it's possible to dither manually. Turns out it's hard but not impossible. My routine now involves setting up a sequence of lights in Backyard EOS - usually something like 30x40s for prime focus work with my Skywatcher 150P and Canon DSLR 600D. Then once the sequence starts, I suspend every 4-5 subs and put my eye to the finderscope and my hand on the dec slow motion or the RA control. Carefully I nudge the scope so the stars move by a very small amount - first north, then next time west then east then south and so on. It's tricky if you are pointing at a patch of sky with only a few dim stars in the finder scope view but I'm getting better with practice. It is easier with a wider field of view - last 2 sessions I used a Takumar 200mm f/4 and it was almost easy compared with the prime focus sessions.

The main benefits are (a) I don't "waste" time taking a lot of darks and (b) satellite trails completly disappear. The downsides are (a) need to stay at the scope the whole time - no opportunity to go inside while the sequence is running and (b) lots more time squinting through the finderscope and hoping I didn't nudge too far

If you look at my gallery then all of my recent images were taken without any darks. There're not amazing by any stretch but I feel like I'm getting consistently better signal to  noise from the end product and I've eliminated the streakiness and walking noise issues from earlier images I've taken.

Compare: 30 x 30s subs @ ISO800 (with 10 x 30s darks) and Canon 600D at prime focus

with 15 x 60s subs at 800 ISO and no darks but with dithering 

Little bit tricky to find a target I can directly compare - there are sort of similar subjects but with different focal lengths.

I'll definitely be trying the Pleiades later in the year as I've not managed to get a good image of it yet that isn't spoiled by too much noise

Beautiful image!

2 hours of 6s exposures - that's 1200 subs to process! You must either have a monster of a PC or boatloads of patience. Either way this is extremly impressive and goes to show that long exposures aren't the only way to skin the cat  Or jellyfish in this case.

I have a skywatcher 150P with RA motor drive and I can get quite pleasing images from my scope. Looks like your optics are very similar to mine but I have an EQ 3-2 mount which looks to be sturdier than the EQ3 that comes with yours. I'd definitely not spend any money on a camera before you have followed @Rallemikken's advice and tried it out using something borrowed. I think you should be able to get 20 - 30 s  exposures with some patience and luck. 

Have a look at my gallery  - all taken with my Skywatcher 150P (750mm focal length) - either using a astro-modded Canon 600D or a Nikon D3200.

Amazing - something to aspire to! 2000 X 60s is an incredible total integration time and the resulting image does justice to all that effort!

Couldn't decide whether to react with 🤣 or 😥 because it's a bit of both.  Thinking about braving it tonight to image Mars and I'm sure it won't be any easier for me!

Not quite as bad an experience as yours - I started recording video too early and filled up my laptop memory with buffering video. Then disconnected the camera too early after the session and feared I'd lost the video - luckily was able to recover the cache of jpegs and reconstruct the video! But had a panic filled 5 minutes while I hunted around in the filesystem!

Also realized afterward  I should have used 2x barlow. Was kind of caught up in the moment - it was spectacular!

Mine seems to be broken too 😄

And I got all excited last night when I was packing up after a short and unfruitful imaging session and noticed Orion starting to climb above the Eastern horizon... winter is coming 

@paulyz and @happy-kat. Good point about the focus. I have also heard that other variations of 150P have issues. I have the skywatcher Explorer 150P and have used both Nikon D3200 and Canon 600D at prime focus without problems with focus.

> AZ stars dicovery wifi, which can carry 5 kg

I've heard (can't recall where) that ideally you should aim for payloads around 50% of max load. Obviously I 'm exceeding that with my setup and it's probably limiting me. But maybe you could avoid this ....

Not sure how far your budget will stretch but you could look at a widefield camera lens combined with imaging camera rather than the using the skywatcher - second hand fixed focal length?

I have a 150p and a canon 600D which has given me some pleasing results. Have a look at my galleries - DSO and planetary. I am particularly pleased with how the 5x live view that means I can give pretty large images of Jupiter at least. I combine with a X2 Barlow but maybe x3 or x4 would be better for mars and Saturn. Not every canon can do the 5x live view with 1:1 pixel mapping - according to what I've read that is essential: https://www.astropix.com/html/equipment/canon_one_to_one_pixel_resolution.html

Having said all that, In my view the key thing to consider is weight - what mount do you have? I'm using the skywatcher eq3-2. If I recall correctly it's got a max payload spec around 5kg and with the tube and the camera I'm right at the limit of capability of this mount. I can manage subs of 30s reliably but that's it. 

@ONIKKINEN really clear instructions and especially appreciate you providing the scripts! I'll try it in some of the test shots I've already taken.

I'm a software engineer so pretty comfortable around scripting just need to learn my way around siril API - you've saved me a bunch of googling and trawling through manuals.

I'm interested in this too. Recently acquired an old Takumar 200mm f/4 lens that shows some nasty purple fringing in my first test shots. I'll preserve with adjusting f-stop and tweaking focus to see if I can beat it but in the meantime I thought I could take the imperfect colour images and convert to monochrome to hide the defect.

I have a canon 600d and use siril and startools to process. Currently use "off the shelf" processing script for OSC with bias, darks and flats for the calibration. Output is a colour fits file.

Absolutely stunning. You put those 100 hours to fantastic use. The second image (HOO rgb stars) had my jaw on the floor!! And it just got better as I scrolled down! 

I've used star hopping with my 150P to find all of the galaxies mentioned above. M31 is in a league of it's own and doesn't prepare you for the misty, ghostly, almost-not-there experience of finding the others. I do my observing from my bortle 3/4 garden where I can just about spot Andromeda Galaxy with naked eye but the first few galaxies I found I had to put a camera in the eyepiece and snap a picture to convince myself I'd found them. 

Definitely go for M81 first - it's one of the easiest to find. But prepare to doubt yourself when you think you have it. I look for a faint cloudiness that stays fixed relative to stars when I tweak RA / Dec to confirm usually. Averted vision is useful once your confident you've located the target but doesn't work for me while I'm scanning the general location - that faint puff of smoke is what I home in on!

I find checking and double checking to the star hop and star chart in finder and eyepiece is essential too - if you are sure you're in the right place then be patient and nudge the scope around with tiny movements looking for that misty patch that moves with the stars.

Best of luck - it's very very rewarding when you do spot one eventually... Photons from something that's 10s or 100s of millions of light years away and packed with billions of stars have travelled across cold empty space to arrive in your eyes that night - possibly the only person looking at that galaxy that night even.

Roll on galaxy season!

I have a RA clock drive mount and no automated focuser or anything else computer controlled so I find backyard Eos almost perfect for what I need with my Canon 600D . I only wish it could plate solve my images when I'm framing!

Really impressed with the image above - I bought identical lens about 3 weeks ago but have been distracted with imaging Jupiter until recently. I assumed I'd need to wait a few weeks more but your results have inspired me to just give it a go. Will be pairing Takumar 200mm SMC with modded Canon 600D - fingers crossed I get anywhere close to your image.

On 14/09/2022 at 16:58, Tomatobro said:

When you have friends round and they know you have a telescope (and its clear) you want to show it off so first it HAS to look like a telescope. Second, when you have Saturn or whatever you can move away and folks can go to the eyepiece and see what you just saw.

You cannot do that with Bins.....

I remember a few years back going to a church garden party when the weather was good and Jupiter and Saturn were both visible. I set the binoculars up on a tripod in the garden and pointed at Jupiter. You could see 3 of the moon's but not much else. Nevertheless people were blown away! There was a queue all evening. 

I would not have transported my skywatcher 150p but the binoculars and tripod were super portable. The other advantage was people knew how to use them with almost no instructions beyond "don't hold them" to avoid vibrations.

@Laurieast I like the colours of the moons! 

Shot on Sept 24/25 around midnight - just missed Europa's shadow due to clouds but managed to keep Ganymede, Europa and Io visible in the processing to show Europa just clearing the western limb and Io about to go behind - with Ganymede out to the east.

Captured from near Bath, UK - latitude 51N. Skywatcher 150P on EQ3-2 (RA clock drive only). Barlow x2 and Canon 600D (astro-modded). 5 min (~6000 frames) captured using Backyard EOS (liveview x 5) at ISO800 and 1/400s shutter speed. AVI's joined with PIPP then used autostakker3 to align, stack and select best 10% for processing in Startools where I balanced colour and sharpened to produce the final image. 

Thanks Elp. I tried the banding reduction and it looked a lot better. Here's what I got when I processed the result using startools. I was able to stretch it a bit more without making the background look too grey.

@900SL it looks like Canon 600D also has a LENR option. I will do a trial using that option too and see if it makes things easier without compromising noise. I think there's probably a degree of experimentation here in finding (a) what works for my camera and (b) making life easy during the imaging session. I'm in south of England so generally thermal noise due to environment is not an issue - but my camera is not cooled and sensor temp is usually reporting in the mid 20s C after an imaging session so it's not exactly cold!

I've been struggling to eliminate noise in my images for a while and keep reading about dithering. I'm using tracking only - no guiding - and I don't even have a computer controlled mount. I just have a clock driven RA and a slow motion control on the Dec but I thought I'd give it a try.  Using my camera at prime focus I can reliably get 25-30s subs with no star trailing once I polar-aligned. Can't go above 30s though. I'm in a Bortle 4 area so the sky is pretty dark and on moonless nights I can see M31 naked eye and find M33 in my finderscope so the background sky isn't too much of an issue.

So on Saturday night I set everything up to image M33 Triangulum galaxy. I have an EQ3-2 mount with a Skywatcher 150P F/5 750mm scope. I attached a Canon 600D (astro-modded) at prime focus and used BackyardEOS to frame the image and then set up 60 x 30s lights.

I tried dithering by suspending the imaging every 5-7 frames and alternated pausing the RA drive, slewing west for a moment and very small shifts north and south. I then wait a few seconds and resume the imaging sequence. I could see M33 in the finderscope with averted vision so I was able to make sure I always kept the scope pointed in roughly the same position. At the end of the session I took 10 flats and for once didn't take any darks, just put the scope away.  

I found the manual dithering quite tricky - especially on the RA axis. Pausing the clock drive was ok to dither east but I have quite a bit of backlash on my RA axis so I'm not sure my dithering in the westward direction was successful. I do have to stay at the scope the whole time and keep count of number of frames so I remember to suspend the session every few frames to dither. 

In the morning I processed the data. First I stacked and calibrated in Siril. The data looks pretty good but there still seems to be some noisy horizontal stripes. I've attached an image of M31 I took about a week previously using darks instead (30x25s lights, 5 flats and 10 x 25s darks) for comparison and there's clearly an improvement. These images are stacked and calibrated and displayed using 'histogram' stretching in Siril - no post-processing.  

Am I on the right track here or wasting my time and better off sticking with darks? The tradeoff is longer imaging sessions but essentially passive: I can go inside to the warmth once the imaging starts and only need to come back out to cover the scope before the darks. I'm just not convinced that not dithering and using darks will really get rid of the noise.

I suggest using that 28mm as you have it fitted now to try and view something during daylight - a distant chimney pot for example. Doing it in daylight removes one major obstacle  

it's also easier to align the finderscope during the day.

Some photos of my 28mm lens in use

If you are both really new to the hobby then I'd suggest binoculars over telescope to start with. If your budget is £300 then you could probably buy binoculars first and if you both really enjoy things, you will still have money for a telescope - these https://www.firstlightoptics.com/all-binoculars/opticron-adventurer-10x50-t-wp-binocular.html are £85 at the moment. Jumping in the deep end with a telescope straight away may put you off - unless you have support from a friend or an astronomy club who can show you how to use it and crucially, get it pointed at something cool quickly to get you hooked.

Binoculars are great to start out with - with something like a 7 x 50 will give you a gentler learning curve but still be very rewarding when viewing Jupiter's moons, the big craters on the moon and deep sky objects like Andromeda M31, Orion Nebula M42 and the Pleiades M45 - https://www.space.com/stargazing-with-binoculars-beginner-tips

The other advantage with binoculars is they are supremely portable. I find it key in this hobby that the less obstacles there are to getting under the dark skies with the right kit the better - remember you will end up standing in a dark field or garden in the middle of the night so more complicated equipment like telescopes will be doubly frustrating when it's cold and dark. To start with I recommend naked eye and binocular observing - learn your way around, get familiar with the constellations, the planets and the moon. That way, adding a telescope into the mix later will be building on a body of knowledge/experience you've already gained - making it easier to make sense of.

Finally, don't feel like binoculars are the poor relation to telescopes. Many astronomers enjoy using binoculars more than telescopes and you can certainly spend a lot of money on them and on dedicated binocular mounts. One of my favourite things to do in the summer time is just sweep the milky way with binoculars. Nothing beats the majesty of that dazzling carpet of diamonds! 

I use https://stellarium-web.org/ to find jupiter and then zoom until I can see jupiter's cloud deck. make sure you are centered on jupiter so that adjusting the clock forward or backward will keep jupiter in view and then the app will easily allow you to find the time when the spot transits. Rule of thumb seems to be it's about 10 hours between transits - so you may get unlucky and pick a night with no spot visible.

For example I can see right now that tonight (2022-Sept-12) the red spot won't be visible until after 3am on the 13th and it crosses the jupiter "meridian" around 4:30am. However, the following night (2022-Sept-13) it's best placed around midnight.

I had a peak at the weekend coming and 2 am on Sunday morning looks particularly interesting with GRS and a shadow from Io visible

Highly recommend naked eye and binoculars to start with. If you have not done any astronomy before and especially if you don't have someone with you to talk you through things like using finderscope, starhopping and generally finding your way around, then jumping straight in with a telescope will be very challenging and more likely to lead to frustration and disappointment than joy and wonder

If you are starting with no experience then I definitely think a pair of 10 x 50s or even 7 x 30 binoculars and a tripod will be money well spent. You can get some really quick wins - the moon looks amazing and is very easy to find! Scanning the milky way on a summers night with binoculars is always an amazing experience - I never get tired of that. Spotting jupiter's moons is easily within reach. You can see globular clusters, open clusters and, if you have a dark sky, galaxies and nebula. The other advantage is you don't need to worry about finderscope or inverted or mirror image views so locating things is considerably more straight forward.

If you are still interested after a season or two then adding a telescope to your equipment doesn't mean you won't stop using the binoculars - they will always be useful and enjoyable for astronomy. And if you lose interest in the hobby they are still a handy thing to have whenout walking or on holiday - same can't be said of an EQ3-2 mount  

stellarium-web.org thinks it's PGC2003403 - see screenshot