gorann

Thanks a lot Paul! Yes, it really works quite well, so yes, very pleased😁 Cheers, Göran

The moon is out and I have had two clear nights using the IDAS NBZ filters (Ha+Oiii dual band) on my Dual RASA rig. Here is the result of the first night. This image was inspired by a narrowband image by Christoph Lichtblau onn Astrobin where he pointed out that these show bows (presumably from a supernova explosion) are rarely imaged although there are plenty of images of Sharpless 115 (the pinkish structure on top) and Sharpless 116 (the small round dot centrally in the image). The shock bows are the Ha emitting curved structures below the Sharpless objects, apparently catalogued as LBN380 according to the annotations by the Astrobin plate solving. For this image I did the experiment of binning the data 2 x 2 (by debayering using Superpixel in PS). It worked out quite well I think. The moon was up so I thought such rather faint structures like these would benefit from increasing the S/N ratio by binning. So, two RASA8 with ASI2600MC and IDAS NBZ on a Mesu200. 2 x 70 exposures of 5 minutes (gain 100), so totally 700 minutes (about 12 hours). Processed in PI and PS. Cheers, Göran

Maybe Baader messed up and put the wrong filter in the wrong holder or box?

So which should I use, Superpixel or binning after stacking?

To do 2x2 binning with your camera you chose the Superpixel option when doing debayering in PI

You are perfectly right Adam - there is absolutely no Squid in that data. I did 8 incremental stretches until I hit severe noise and also checked each stretch with Equalize in PS. Maybe your initial suspicion of accidentally using a Sii filter could be correct?

The nebula looks great! The background sky is a bit brownish - maybe you could see what it looks like if you turn down the red signal a bit, for example by tweaking the curve of the red channel.

Adam, maybe you could post a tif-file of the Epsilon Oiii data - maybe someone can find a squid in it. It would be a fun challenge.

Good to know - I was almost tempted to get some of those CMOS optimized although I have hard to understand how a filter can be optimized for CMOS rathern than CCD.

That is a great squid Adam, especially at f/4.6! The ASI2600MC - NBZ combo is really something else. But it is of course very odd that your Epsilon did not do better with a mono version of the same sensor. Was the 4nm Oiii filter made for fast telescopes? If not the Oiii may have fallen outside the bandwidth. PS. I recently had an attempt on processing Telescope Live data from Spain on the Squid. It included 37 hours of Oiii with a Tak 106EDX4 (f/3.6) and a FLI PL16083 CCD. It was more noisy and showed less details than my 6 hours with the RASA8 - ASI2600MC - NBX.

I do my processing in small increments and I can see that my final version was nr 57 of previous saved versions, so it takes hours for me too.

Sorry for the late reply - I first missed your comment. It was nearly a year ago so I cannot recreate exactly what I did but I can see looking at the saved versions that I also had a very red image initially with a rather faint blue signal. I do most of my processing in PS and two things I did that helped lifting the blue was to first use curves in PS to lift the blue signal (this was done after the initial stretching of all channels using curves): Then I used Selective Color in PS to swing the magenta towards blue: Those two adjustments helped bringing out more blue. I hope it will also work on your image. I am also at a Bortle 2-3 site and if you have more light pollution that may possibly suppress or drown the blue signal.

Yes, but one less thing to blame if I get odd stars in the corners.....

You are right! Thanks Wim, I feel much better now😁

Then my jig is finnished. I found a bed-side table on sale for about 20 Euro that forms the basis of the construction. Good news was that I could not see any wobbling of the bright central spot in any of my three ASI2600MC, but it felt at the same time a bit frustrating to have built the thing just to find that I did not need it🥴 Cheers, Göran

Great, informative and convicing post Alan! Thanks a lot👍 Just one question: is there any risk for light leaking in through the gap in the ASI tilt adjustment plate?

I fully agree with Olly. The job for a RASA (or other short FL low f-ratio scopes like the Epsilons) is not go show fine detail in distant galaxies. When viewed at the right image scale (up to A3 I would say) the images are crisp. What I have done on occation is to supplement the image with higher resolution data from my longer FL scopes. A great thing with the RASA is that seeing is almost never too bad for it. At nights when bad seeing gives me a guiding RMS around 1.5"/pix the RASA images still look great while imaging with anything above 1000 mm FL becomes rather useless.

Yes it is a truely great camera! I allways run mine at gain 100 and offset 30. Gain 0 works fine too but after an initial comparison I thought subjectively that gain 100 gave a slightly better result (but at the cost of more subs to handle)

Why not just screw two pieces of round (or square) wood next to the hole and press the camera up against them by hand while you rotate the camera. That should keep it centered. However, I have not gone to IKEA yet to get the base for the jig so this is just speculation in my inner theatre.

Yes, that is what I meant! Sorry guys😉

Nice, but for now and especially the future southern Europe must be cooled-camera territory😎 You clearly have the resolution - just need to get the S/N down.

Thanks Olly!

And here is the setup from last night waiting for clouds to go away. I have one laptop for each camera (including the piggy back) and one running the mount (Cartes du Ciels and PHD2). All to reduce the chance of total computer/USB failure.

Just for the record. Here are two more images caught with the rig. No flex issues as far as I can tell. The first one (part of Sh2-126 with LBN437) is only 2x1 hours before clounds stopped me, so a double rig was probably essential to give a decent S/N ratio. The second one is 2x3 hours. 6 hours help for faint IFN (MBM54 with the galaxy NGC7497 in the background). Cheers Göran

Thanks! Well, I finally gave up before the clouds did....