Ouroboros

I'd welcome the comments from experienced pixinsight users on this. In the screen shot below, the image on the left is batch preprocessed data. The image on the right is manually preprocessed stepping through the chapters in Inside Pixinsight 2nd Ed by Warren Keller. I followed Warren's recommended settings. The only difference is that in the case of the manual processing I applied Canon Banding Reduction to all light frames after calibration and debayering but before integration. Also in image integration I applied large-scale pixel rejection. You can see there is a huge difference in the two outputs. I have only applied STF and no other post processing. The batch preprocessed data has a horrible red cast and there's a lot of banding. The manually processed data has lost the red cast and much though not all of the banding structure. I was hoping I would improve the banding by applying CBR to each light subframe separately, but I was surprised to have lost the red cast and some of the colour noise too. Incidentally the red has gone into the high rejected data image. The manual looks like a better starting out point for post processing than the batch preprocessed. Is this difference to be expected? [The data was collected 20 September to test for the first time KStars controlling my mount, guiding, dither and DSLR. There are 33 X 5 minute light subs. Bias and flats taken, but no darks. ] PS I should have added that applying canon banding reduction to the batch preprocessed data was very ineffective.

Yes that is nice. Love the grey "moodiness". Nice and sharp too.

@kirkster501 Nicely explained. Thanks. I suppose I might have to have a go at some of these things if I ever do mono using filters. I have enough trouble doing one shot colour with my DSLR. 🙂

2-3 or 5 hours to get there? Phew? That's dedication. Yours is a stupendous image of the sort of quality we normally only see from people with permenant set ups. The processing must have been interesting! 🙂

Superb indeed! What's tone mapping in a sentence or two?

Yes, same here. I balance up first with camera attached even if I subsequently replace it with my eyepeice to do the three star alignment. I nearly always find I have to adjust the pointing of the finder to that of my eyepeice or camera. This is easily done by pointing the scope at a bright star. One hint if using the DSLR camera at the scope for the first time .... it's worth setting a delay of 10s before the shutter opens to allow any vibration to dissipate after pressing the shutter button. Or use a cable release if you have one.

OK I think I (kind of) get it now having played with it. Does this sound reasonable? I'm using the calibration module. So I set ADU to 5500 (tolerance 1000) which is roughly one third of 2^14. Is that reasonable? I have discovered that the ADU calculation only works when files are saved as FITS. So, starting off at an exposure in my case of 0.25s KStars keeps taking images until it gets the exposure to a level near 5500. It then starts saving the number of images set in the counts box.

Cracking image, Steve! So nice to have the additional info too. When you've got a long term project like this on the go do you leave everything set up for the one object or do you look or image other stuff too?

For several years I set up on a large plastic sheet with an old plastic coffee coaster placed under each tripod leg. It's not ideal I have to say but it worked. I even stretched out a long sheet of plastic to walk back and forwards to the house. Is a small area of paving an option? That's what I use now. It makes a huge difference.

Thanks for that. Yes, I hadn't thought of the FITS aspect, but as it happens I'd set it to download 'native' so I'm getting all files as CR2. I've had a quick go at getting flats by as you say to use AV mode to get exposure. I ran into two problems. Firstly, pressing the shutter in AV mode locks up the camera or KStars requiring everything to be restarted. Secondly, EKOS doesn't seem to give me access to all the available shutter speeds on my 450D. As I say, I only had a quick go at it so I need to play some more to get a better idea of things.

I almost always set up during the day. A compass gets me close enough to see Polaris through the polar scope, and with enough mount adjustment to polar align. What I like about setting up so early is that I've got time to carefully balance the scope, set up my computer, and make sure the mount and cameras connect up and are working. I then come inside, have something to eat, get changed into my warmer clothes before going out just as Polaris makes an appearance. Minds you it helps being retired. 🙂

I'm less keen to go this year because it's in November. Previous years it's been earlier in the year as I recall. Easier travelling.

Lovely picture. Nice to spot some familiar objects including the North America Nebula next to Sadr and the nebula around Deneb. Is your Canon modified? There's a lot of red picked up.

Yes, it put me in mind of The Wrong Trousers.

I also wear thermal long johns under lined walking trousers bought in Mountain Warehouse. They're pretty cheap. I've got a couple of pairs. Walking trousers have lots of pockets for mobile phone, chewing gum, tissues, and somewhere to put lens caps. Thick socks are essential. Top half I wear T shirt, long sleeved thermal vest, long sleeve poloneck, thick woollen jumper and fleece or lined coat if it's really cold. Oh, and woolly hat. Something I've found is not to get cold before I put all the clobber on. It's difficult to get warm once you're cold. So I tend to start off wearing more than I need. It's easier to take outer clothing off if necessary.

I decided to get one, fit it and take the plunge on cutting the box. As you suggest, a Stanley knife sliced through the foam very nicely. The only thing is that the focuser would stick out the wrong side. But by rotating the telescope 180° in the rings it points out the other side and it's at the top which is more convenient for the surgery on the box. It's also necessary to cut a slice out of the foam in lid because the bracket sticks up. I can still get all the components like the final reducer in their pockets, and there's also plenty of space in the box for the focuser controller and cable.

I thought of doing it the second way you suggest. But I'd have thought I would have to disconnect the camera from EKOS to do that .... and then reconnect*. Do I not? As for your first suggestion, wouldn't it actually be easier to set to aperture priority in the INDI panel? I'd try it now but I'm not near my MacBook and camera.

What is the best way to take flats when using a DSLR in KStars? I expected I'd be able to set camera to aperture priority and to bang off some flats as I normally do when using Backyard EOS. That doesn't seem to be possible in EKOS. Or is it? Any suggestions? PS in the end last night I disconnected the DSLR from the MacBook and took the flats manually at the camera.

Assuiming all things being equal then statistically the signal to noise ratio will double when you take 4 times as many subs. In reality contributions to noise and image quality can change over an image session - thermal noise, light pollution, seeing, focus and so on. One of the advantages of long imaging sessions is that you can afford (possibly) to throw away the poorer subs. More is not necessarily better. But more better is definitely better, if that makes sense. 🙂

Yes, I agree. As you suggest, daytime alignment of the polar scope is much easier. The problem I had was finding an object high enough to see through the polar scope. The declination axis only goes down so far. I had to tip the mount forward by shortening and lengthening different tripod legs. I did find that the polar scope on my newly bought AZ-EQ6 mount was misaligned. Frankly I think that's unacceptable for something so expensive.

Wow!

Magnificent. It's worth zooming in on the central bit. It looks like both cloud and rolling surf.

I bought some flexible twin-core cable in B&Q. I can't now recall exactly what the current rating is but it is sufficient for the OP's requirements which are the same as mine. When I clear away I just loop it like lawn mower cable and hang it on a hook in the shed.

Well, it certainly works. I don't do much lunar photography, as the next question will no doubt illustrate. How does stacking help? Registering and stacking helps in deep sky photography because it improves the signal to noise. But the Moon is so bright I would have thought you don't need to improve the S to N. Also couldn't stacking work against you because atmospheric turbulence can cause different amounts of distortion in different parts of different images. So when you stack them they become "fuzzier"?

That's a nice contrasty image, Charl. Have you done any processing or is this 'as is'?