gorann

My second attempt at catching nebulae in Cygnus with the RASA8 and ASI2600 OSC. Quite a lot are going on in this area. In this image I especially like det mix of dust and dark nebulosity. The RASA is great to have when nights are short, like right now😎. 179 x 1 min, so about 3 hours. Gain set to 100. Stacked in PI and processed in PS. Happy with most things except peripheral star shapes which takes som effort to fix in PS, after the worst is cropped off.

Yes, the RASA 8 also have the USFS, probably adopted from the 11" V2 as the RASA 8 was the last addition to the family.

What is the difference between V1 and V2 of the RASA11? I assume it has to do with the holding/focusing of the primary. I think the RASA 8 came last so it was maybe V2 from the start.

Thanks for that advice Vlaiv. I am running 2 min exposures tonight with the RASA f/2 so it should be managible since I will probably only get about 3 hours before dawn up here.

Sound very promising, except for the tilt issues.

Thanks Vlaiv for clarifying things as always! Then I stick to gain 100 with my ASI2600 and live with the large amount of subs. We were only comparing the camera settings because Datalord has one camera and I have the other (ASI) but as I expected they are not really comparable since the chips are different.

The ASI2600MC has the Sony IMX571 sensor and the QHY247C has the Sony IMX193 and I do not know the difference between these. By the way, have you ever had to collimate your RASA and does it hold focus over the night? My collimation appeared to be perfect when it arrived and focus is spot on all night. These are usually problematic thing with fast telescopes but maybe not with RASA. The probelm I do have is star shapes that probably are related to minor tilt.

Yes, you are right, 50 k full well at gain 0 and around 20k at gain 100. But I think I read somewhere that the S/N will be lower if shoting at gain 100 with more subs, than at gain 0 with fewer subs. For M31 I tried both gain 0 (60 seconds) and gain 100 (30 seconds) and did not see much difference. I do not understand the gain-scale for the QHY in your graphs and how that translates to ASI gains. We should get Vlaiv @vlaivto explain this. One good thing with the ASI2600 is that it is 16 bit and I love that it has no amp glow whatsoever, so I see no reason for taking darks.

With the RASA8, which I bought second hand (apparently hardly used at all), I got the dedicated Baader filter drawer, so changing filters for NB imaging should not be much of a hazzle but I have yet to try it (I am waiting for the moon to get up before I change to my ASI1600mono and the filter drawer. I will report how it works. The ASI2600MC I now have on the RASA8 is probably sensitive enough to do NB even if is an OSC, but the chip distance is 17.5 mm so there is not enough space for a filter drawer with the RASA. Then of course you need the Baader special fast focal ratio filters at f/2. I have the Ha one but yhe Oiii is on back order until October (since Baader is making a new batch).

You caught a nice version of M33 there! It depends a lot upon the gain or ISO setting. The ASI2600 has a sweet spot at gain 100 (some extraordinary electronic thing happens to the S/N ratio), but at that gain it is quite sensitive. My M33 was with 2 min subs since there are no very bright stars there and tonight I am shooting Tulip nebula and surroundings with 2 min subs, but last night Sadr was in the frame so I had to go down to 1 min, and stacking took 5 hours.

Great image - must be nice to have forgotten data😉

Thanks! Yes, there always seems to be something that remains to be done to improve an image.

Thanks a lot! Yes, the setup has been quite productive so far. F/2 helps when astrodarkness is still only about 3-4 hours up here. One problem is that stacking these 50 Mb files, which for some reason become 300 Mb after debayering, takes longer than the actual data collection. And at f/2 the exposures have to be short - have maily gone for 60 s, which meant 180 subs in 3 hours last night, so I am still stacking those.... Fortunately external harddrives are cheap nowadays.

Thanks a lot!

Realized that the image sharpness could benefit from some deconvoluton and more distant dust could also be brought out:

Soon, just have to download all the photons up here first😎

Have you for some reason excluded concrete? I have three obsies with a reinfoced concrete pier in each. Very cheap to build compared to steel. For the last two I used a 20 cm roaddrum but for an EQ6 sized mount 15 cm would probably be more than enough. At the bottom I have a 60 cm deep concrete cube of about 500 kg, but you could probably get away with less but I want to be able to put my Mesu or EQ8 on it. Here are images from this summers build.

Yes!

I could try to do a separate lum processing - cloudy here so nothing better to do AP wise.

Yes, I know. Just have to avoid bright stars. And I bought this second one used in mint condition for 850 pounds, so I do not feel too bad.

Thanks! I see, interesting thread. An APS-C mono will be a real bestseller. I just bought a second ASI1600MM, maybe I should have waited but.....

Are you sure about an ASI2600MM coming out? ASI denied it in May, but you may have better info: https://www.facebook.com/ZwoDesignAstronomyCameras/posts/hello-zwo-there-will-soon-be-a-new-mono-camera-based-on-the-asi2600-/2807313975984474/

I love the spoky shape of that dark nebula - seems like it is dancing against the golden star field. Great image!

I echo beautiful! 👌Sadly it will always be below my horizon up here🥴

I liked the first one, and then it just got better and better! My be sad to travel home.