gorann

Thanks Dave! The RASA8 and the ASI2600 appear to be a nice combination.

I would guess we both have a slight tilt problem. There is tilt adjustment on the ASI2600 but I am not sure I want to try to fix it. When the moon is back I will start collecting Ha with an ASI1600 - it will be interesting to see if I am more or less lucky than you.

Thanks a lot Mark!

Yes, probably easier for me than trying to fix the tilt. Very small margins at f/2. Are your elongated stars in all corners? Maybe your chip distance is a bit off?

Thanks! Yes I am quite plesed and last night I also organized the camera cables better so I got rid of the spikes, as seen in my M33 image (just posted).

Thanks! Yes, my stars were also elongated in some corners probably due to minor tilt (not chip distance since one corner looks good). I simply fixed them with an old trick in PS, took 20 minutes. The way I did it was to make a duplicate layer and then in blend mode Darken move that top layer with the arrow keys until I get round stars and use the brush tool on the layer to apply only in the affected area. Have to do it separately for each side or corner as the elongation was in slightly different directions.

My third image with my new RASA and ASI2600MC (I am still processing the second one) and the first one (M31) is here: Obviously this 400 mm FL scope is not really a galaxy hunter so I have gone for the biggest, M31 and M33, as seen from Earth. From now I will aim at nebulae. Stars look better than with M31. The spikes are gone after I organized the camera cables in a circle. A lot of dew but no dew heater seems to be needed since the camera releases enough heat inside the dew shield. 88 x 2 min at gain 100 (offset 30). EDIT: Added a new version benefitting from deconvolution and a bit more distant dust.

Thanks Datalord! Yes, it is remarkable, especially since it will not break the bank compared to all other "astrographs".

I have been at the lookout for a wide field scope (what some people call astrographs) and this spring I came across a nearly unused RASA8, and after 6 months waiting time, due to the virus situation, I finally received an ASI2600MC - an APS-C sized cooled OSC with relatively small pixels (3.76 µm) that kind of fit the 400 mm FL of the RASA8 (ca 2 "/pix sampling). As I allready had my two obsies filled up with other scopes I decided to spend the summer building a third obsy for the RASA to put on my long-time retired NEQ6, my first mount bought in 2014 when I started my AP adventure, but having been laying in a closet for the last five years, beeing replaced by an EQ8 and a Mesu in my other obsies. Up here astrodarkness started a few days ago, and on Saturday I could finally get the first light out of the RASA and ASI2600. I thought I would go for something simple, at least something I could easily find with the NEQ6 and hand controller: M31. I have to say I am very impressed with both the scope and camera. The collimation of the RASA was spot on (round defocused stars) and it maintained focus all night, although all night here is now only three hours. I am equally impressed with this new ASI camera. As promised there is no amp glow so no need for darks. There was also virually no vignetting by the RASA8 although it is stated to perform best up to an image circle of 22mm. The diagonal of the ASI2600 is 28mm. However, the stars in the corners were a bit elongated, probaly due to minor tilt, but trying to fix that on an f/2 telescope could be quite challenging and it will at least not be my first priority. Andromeda fitted with margin so I could crop away the edges. I don't think anything I have set up to do in AP has been as smooth as this. Fortunately I found that Baader make a 7.5 mm T2 extension that is what is exactly needed to fit the ASI2600 to the T2 adapter of the RASA to get to the 29 mm chip distance. The ASICAP program I use for my older ASI cameras did not work with the 2600 but I soon found out that there is a new ASICAP hidden within the new bundle called ASIStudio. Focus was easy and it kept all night - I have heard that about the RASA before (like on Chuck's Astrophotography on Youtube). So my conclusion is that the RASA8, even being an f/2 scope, which is supposed to be extremely tricky to use, is very easy to get working. I think that bad rumour may come from the Hyperstar attachement that you can fit to SCT scopes, but the RASA is dedicated to this and apparently hardly ever needs collimation. Olly @ollypenrice, may have a comment? My only complaint so far is the star shapes that may not impress pixel peepers (including me) but I think I can improve on them by organizing the two cables to the camera in a curved form - I am trying that out tonight on M33 (EDIT: It worked, se my M33 post). So, enough rambling about the RASA, here are my first 90 minutes (180 x 30 seconds at gain 100) aquired with the RASA8 and ASI2600. No flats (I did take some but it looked better without) and no darks (not needed with the ASI2600). Stacked in PI and processed in PS. I also tried 70 x 60 seconds at gain 0, and it looked similar but not really as good. I should make a thread about the obsy build - I had to go to plan C before it worked out. Cheers Göran EDIT: at the bottom I added a non-cropped version including both the gain 0 and gain 100 data, so totally 160 minutes and a bit more dust and core details.

Clutches are also for safety and need to be able to slip in case you fall a sleep🥱 before a meridean flip run the telescope into the tripod🥴. As long as you have the telescope well balanced the clutches do not need to be very tight at all.

Thanks Steve, not the least for finding my three year old posting!

Yes, if there is no colour signal in the structures they will be B/W when you just add lum. You could try to stretch the RGB data to sea if you can find any structures before adding the lum (which was only from the green channel if I got you right).

As I said on Astrobin, I think you have teased out more details in there than I have seen before. HDR is not cheating - taming the dynamic range is the key to all processing. A linear version of M31 would be very uninteresting (or maybe interesting to see but rather ugly). Overall it is a great rendation of M31 Rodd!

As I just said on Astrobin, that is a stunning mosaic Olly with the squid in one end and the Crescent in the other! Never seen them together. Outstanding indeed. Superb processing, but now you cleraly lost your arguments against OSC, at least the new CMOS generation 😉

Your 16 panel Ha image is just great - I will save it for reference when looking for targets in Cygnus. I still wait for the stamina to attempt to do big mosaics like that, maybe when I retire.....

If you are into imaging I suggest you stick to your Newtonean, which is not a bad imaging scope, until you saved up enough for a good 80mm triplet apo (like an Esprit) - that would likely be a scope you would keep for wide field imaging even if you later buy a larger scope. Every time you sell and buy a scope you loose money.

Sorry to be late into this thread but I have been busy outside building on a new obsy (good exercise and why only have one when you can have three...). I must join in wishing you Vlaiv and the wife a speedy recovery. Statistically you should soon be fine (99 % confidence) since the nasty lingering symptoms are rare. Clearly you are currently well enough to provide your normal key input on SGL! Just a small comment on the cooling issue. When looking at the temperature vs noise curves for the ASI CMOS cameras I see little reason to ever strive for a delta T of -45 °C. I have heard that it is rather hard on the cooling system to run it at max, so I usually go for a delta T of about 35°C or less. Here in Sweden I set my ASI1600 at -20°C but then then nights are rarely above 10°C during the astrodarkness season (Sept - April), and when I was in the Australian tropics in December I settled for running my ASI071 at -5°C and there was not much noise to worry about. So Rodd, with the current increase in global temperatures, maybe you should just settle for -15°C and get a new set of masterdarks😎

Yes, very tricky. I love the blue Oiii signal but when I try to bring it out it messes up the nice Ha structure in the nebula. It just comes down to negotiating one over the other and to find an ok mix. So far I think Ciaran has come closest to a good mix. Here is my stretched version of the Oiii data - looks nice (except for the gradients in the edges), but it is just so difficukt to mix nicely with the Ha. Clearly it is a nicely structured shell of Oiii around the nebula.

And me! Gives me just about enough time to build a third obsy so I will be more than ready if the weather collaborates......

If I started off from scratch I am sure I would end up with something different from this first attempt (now in saved version 19 on my HD) - almost tempted to try. I do have some initial workflow but soon it drifts into trial and error and inspiration / desperation🥴.

Had another go at it this rainy day and I think it improved from my previous versions, but maybe I should have had some 8% IPA like Ciaran when he processed his excellent version🍺

I always keep my original subs and all the versions created during my processing (with backup on a second drive), but I sometimes delete the intermediate files created by PI when calibrating (those can allways be recreated). As mentioned, terrabytes cost nothing nowadays and I feel it would be a waste of time finding files that can be deleted and I rather just buy yet another external hard drive.

Wow, that is nice Wim. I need to look up tonight when I take the last walk with the dog🐕

Found another successful user of the TS 130: https://www.astrobin.com/users/jdurand/

It probably has to do with my version of PS, which is CS5, so a bit old (but free from subscription). Here Camera Raw does not have any filter functions (it is not in the Filter menu), it only pop up when I translate RAW images from a DSLR to tiff. So I need to hold on to my Esprits since they come without colour fringing, apparently unlike a Japanese brand.