wimvb

That came out very nice, Göran. Great contrast between the billowing Ha and the very dark structures below centre. Now you're just acting spoilt. 😉

A short update with images. During summer recess (May - August) I did some more work on the obsy. The biggest task was to replace the rubber wheels under the roof beams by proper v-rail and wheels. This lifted the roof by about 5 cm. As a result there is now a gap between the roof and the south wall. I need to close this with a board or I'll have the largest pigeon coop in the neighbourhood. Compare the last image here with Firas' image from earlier this year. I did some work on the outside, including painting. Inside I sanded the floor boards and treated them with wood oil. The boards are a bit warped and have a very rustic look after sanding. And finally I installed a box (60 x 40 x 40 cm) around each pier, where I can have power and network outlets. I also have a permanent power and ethernet cable from the house to the obsy.) Late this afternoon I put the mount back in its place and got the 190MN in. Next will be to attach the camera and wire everything. Next weekend I expect to be up and running. Btw, up and running: my knee is doing well now. I can bend it almost as much as before my accident, and have nearly full strength again.

Just check a single sub. A focus issue will show up there.

When I had my pentax dslr connected to the Baader cc, just the t-adaptor gave the correct distance. Most (mirrored) dslrs have a flange to sensor distance of about 44 mm, and the t-ring thickness is 11 mm = 55 mm. https://en.m.wikipedia.org/wiki/Lens_mount

Very nice result indeed. The stars look like tiny doughnuts, which suggests that focus can be improved. Perhaps focus shift?

Actually, both cameras have exactly the same sensor size in mm, so they will also have an identical field of view. (Olly beat me to it. He's faster on the 'submit' button.)

The zwo asi 183 and 533 have a similar fov at less than half the price. So the question is, why expensive ccd when much cheaper cmos is an alternative?

If you happen to aim just right, and get perfect polar alignment, then dithering in ra only wouldn't work. Reshuffling the subs can produce an apparent drift in ra. But if there is dec drift due to polar misalignment, ra dithering will break up the dec drift pattern, as your sample images show, and walking noise should be reduced. So there is a trade off between acceptable drift (elongated stars in worst case) and acceptable walking noise. My guess is that in most cases, ra dithering will improve image quality. But aiming for perfect polar alignment may be counterproductive. For dslr (and osc cmos cameras), a dither of at least 12-15 pixels is preferred, according to Tony Hallas. A larger dither will mean that you lose a larger area of your subs in stacking edges that need to be cropped. If you have a large sensor and/or small pixels, that may be acceptable.

The star adventurer mini has an app which allows dithering without guiding. My guess is that the mount speeds up or slows down a random period. There is a setting in the app called ”dithering range”. The range is measured in arc minutes.

Random in one direction can become the same as drift by reshuffling the frames. That’s why, as I believe you imply, two directions are needed.

In theory. But a drift between subs can cause so called walking noise, streaks in the drift direction. And RA dithering can be equivalent to such a drift. That’s why you need to be cautious with RA only dithering. It is possible to eliminate walking noise by careful calibration and stacking, but it requires expertise in stacking. Two dimensional dithering is more robust.

I’m not convinced that dithering with an RA only mount will do any good. Since the order in which you stack all subs isn’t important, you could lay them out as a sequence that shows a continuous drift. Unless you already have natural drift in declination. Ie, you need a polar misalignment in order for a RA dither to work. @Stuf1978: very nice image, btw. Especially considering the conditions re moon and light pollution.

Welcome to the money pit. 😉 Enter here https://www.firstlightoptics.com/books/making-every-photon-count-steve-richards.html

You'll need a watch. An accurate one.

You know, Göran solves such a problem by building a new obsy now and then. Sometimes I wonder if he’s secretely competing with Deep Sky West (not Midlands). ps don’t let him know I told you that. 🤫

Interesting. I once made a refractor out of wooden sticks, paper and two simple lenses. Maybe we should start a business together. I bet we would be hefty competition to SkyWatcher.

The more, the merrier. Looks very nice. But what is the cardboard for?

Sounds like you fried it. Contact @FLO, they will advise you what to do.

While you all were discussing colours and the benefits of aperture, I have been entertaining myself with the data that Göran provided earlier in this thread. Background neutralised and colour calibrated using Photometric Colour Calibration in PixInsight. Then used Arcsinh stretch, which preserves colour. The left half of the dust cloud was considerably more gray than the right half, but playing with colour saturation in Curves Transformation in PI sorted that out. Btw, @gorann, you might want to point your 14" barrel at these dust clouds, because they hide a few very interesting objects. I even found a few galaxies in the distant background. But those would require more than your Meade.

So, not just aperture fever, then?

Great image, Göran. There’s a weak Ha signal in the 2 h version, that I miss in the 6 h version. A passing Ha cloud, or did you hoover up the last seconds of the sunset as well. 😁

https://www.weatherstations.co.uk/hydreon.htm Perhaps? It certainly looks futuristic.

Don’t stream 4k quality 😉. With a lower resolution and frame rate you should be fine. And you only need the camera when there is an actual risk for collision, so not all the time. Security cams should have better night vision, but they often use IR LEDs, which can interfere with AP. My camera is mounted on the South wall, looking at the door. It just covers about half of each pier& mount. So I can see the mounts slewing, but not whether they hit the pier. Most security cameras have motion detection and sometimes sound detection. You can program them to start recording or take stills, on motion or sound. Good to take images of the local night life.

My security camera (D-Link) is connected to wifi and has its own app, completely separated from the astro software. You can do the same with a web cam, have it active in its own app. If it’s on the obsy computer you can connect to that computer’s desktop and run the app from there.

I would say so, the pulley has 12 teeth. 12 * 10.2 = 122.4