gorann

I like your version a lot Valiv! Detailed, soft and spoky! Why did you downsample it before posting? I like to zoom in, especially here where we try to see what we can get out of the data and learn from that.

Yes, but in no way as good pixels as in the IMX571 of the ASI2600 (or other brands with that sensor). You can always bin but I never found a need to do that. It is just no way the 071 can compete in image quality. I think the hang up on pixel size is a left over from the CCD era where pixel size was almost directly correlated to sensitivity. That does not apply when comparing CMOS sensors of different generations.

With astrodarkness gone up here now I could of course not resist your data - I knew it would be good as many times before, so thanks for posting it Rodd!

Rodd, maybe this one is more to your liking regarding the colors (tweaked the channel curves a bit).

Hi Rodd, Adrian @Adreneline is right, putting the stars back is a bit tricky. They easily get dark ringed (panda eyes), which I think looks awful, but I found various ways to fix that. The easiest (in PS) is to select all the stars (using Select -> Color Range) and then expand the selection (usually about 3 pixels) and feather it (1 pixel). Then I use a curve on the selection to brightenn the area (ring) around the stars. It may be necessary to do it selectively on different parts of the image depending on the background (nebulosity of dark sky). There is probably a similar way to do it in PI. Yes, Rodd, I was unsure about the colors. I did bring down the blue in the dark sky after I added the stars, but it can be easily adjusted up again if someone likes that better. I always found it difficult not to end up with a pink/mageta color on this nebula because of the Oiii shell around it. If I move it towards deeper red then the shell becomes less obvious also on the main part of the nebula and is mainly seen around it. Assuming it is the Oiii on top that Ha that turns the red to pink, maybe that is how it should be. Here is a tif file (16 bit since it is done in PS) that you can play with. As you say the image would probably benifit from being tuned down a bit, making it less contrasty, I just wanted to see how far I could go. Rodd NGC6888 HOO Gorans version.tif

Rodd, I had a go at your data using the h90 and o65 and started off as HOO and then tweaked the green towards blue as I am no fan of green in AP. After a series of initial stretches I made a starless version (with Star XTerminator in PS). That one was treated with the new RC-astro Noise XTerminator and then stretched and HiPass filtered (all in PS). I also used a bit of Topaz Denoise to sharpen it a bit and reduce the noise further. Then I brought the stars back at a reduced level (as a layer adjusted with a curve in PS). I also tried to fix the oblong stars in the corners a bit. Here are the starless and starred versions. I also added a less pink vesion. Cheers, Göran

I did not know this. I have used Star XTerminator for PS for a while and where is the image with just the stars? I use the original image for bringing back the stars (blend mode Lighten in PS). I think it is a great image by the way Rodd! But have a go at trying starless processing. It really helps getting the weak signals out. I could not live without it now.

With a dual band filter and an OSC you can pick that Oiii up. This is what I got with an NBZ dual-band (Ha+Oiii) filter (RASA8 and ASI2600MC) even under a full moon which is generally not great for Oiii (but OK for Ha). Cheers, Göran

Reagarding 071 vs 2600, you should go for the 2600. I had an 071 (now sold) and in addition to amp glow, lower sensitivity and more noise, it was also often fogging up. So I regularly had to take it apart to dry the silika pills inside in a microwave, and opening it up leads to dust paticles on the sensor unless you have a cleanroom. Never have had to do that with the three 2600 I now have. I also thought the 071 was discontinued (or soon to be).

You can tell the sofware running the CMOS camera to bin (e.g.2x2) and it will save smaller files. I do not do that since hard drives are cheap (on average I image 50 - 100 nights a year with two or more scopes with APS-C cameras each night and it still takes me 2 years to fill a 5 Tb harddrive that costs about 200 GBP). I guess I do not like the feeling of loosing data, even if I do know that it may be empty data and I may as well save binned data. Binned data is also faster to stack and process. But if I save it all then I have different choices of how to bin it, some better that other (Vlaiv tried to explain it once). What I do is usually to downsample the final processed image to a degree where I see no loss of resolution. I guess that is also a form of binning.

6 x 8 is better than 6 x 6. You should really consider building it yourself. I came up with an alternative roof solution for my obsies, which makes the build a bit easier. And it was later copied by my friend @wimvb

I have built myself three obsies here (I live on the contryside so garden space is no issue). Two of them are 250 x 250 cm and very convinient. Then I for some reason tried a smaller design (180 x 180 cm) on the third one and I regret it. Very complicated to move around in there, and a higher risk of disaster. So if you can find something bigger than 180 x 180 cm (6 x 6 feet) I would highly recommend it. Also, you may soon realise that your equipment will keep in a much better condition if you insulate the obsy and use a small radiator to keep it a few degrees above ambient temperature. That means less humidity, so no mold on the lenses, no corrosion of the mekanics, and humidity is not good for the electronics. But with a small obsy, adding insulation would make it even smaller.

Thanks Steve! Yes, apparently IR penetrates dust better than visual light, so there will be a lot to enter into catalogues.

With my ASI 2600MC, things stop working if I failed to connect the 12 V power (so USB is not enough). Have not tried my ASI 6200MM without 12 V but I expect it would be the same. So all power need to be connected.

Thanks a lot! Much there to explore with a longer focal lenght scope.

The most stressful part of imaging for me is aquiring the data, because then a lot can go wrong and time is ticking towards sunrise. I really enjoy the processing as then there is no stress and I can try all kinds of filters and processes and aways step back if something does not work. The more you learn about processing, and the more tools you get in your tool box, the better and more rewarding it gets. For me it has taken years and I still feel I am progressing and have much more to learn. Fortunately, I found that I always liked processing and I think my critical eye has evoled in paralell with my skills. So what I thought looked great in the beginneing made me pleased back then and kept me encouraged. I hope that will be the same for most going into the astrophotography endavour and that they will feel they make progress, and I expect many will make progress faster than me, since I was 50+ when I started.

Nights are bright so I am reprocessing RASA 8 data from last season, focusing on those I collected before I got hold of Star Xterminator. That filter makes quite a difference as I can stretch the nebulosity more. With this image, I was impressed how well Star Xterminator takes away stars and leave even small galaxies, which made me realize how densely packed this image was with galaxies, some looking like grand design galaxies (so please zoom in). The prominent central structure is LBN438, which is catalogued in Lynds' Catalogue of Bright Nebulae, but it is quite dim and demands rather deep data and stretch. Its magnitude is 16 and the surface brightness only 23. It is 30 arc-minutes long. There are more LBNs in the image including 435 and 440. The nebulosity is part of the Lacerta Molecular Cloud. This is actually only 4 hours (2 x 2 hours) with my dual-RASA8 rig with ASI260MC, but it must have been quite dark on that September night in 2021. Processed in PI and mainly PS. Here is the image together with a "crude" plate solve from Astrobin and an annotated one with the galaxies done in PI. Cheers, Göran

Patience is the key. I rarely spend less than a day on processing an image, with many small steps.

Thanks a lot Fegato! Nothing special. I always stretch in several small iterations (7-10 usually) using an S-shaped curve. Then I made the starless version and stretched once more shaping the curve to increase dust and suppress the sky. Finally I Hi-Pass filtered the starless image to separate out the dust a bit more. Then I added back the stars as a layer and controlled their size with a curve. All in PS.

Impressive Steve, which empasises the natural brightness that somehow comes out of the RASA. Cheers, Göran

Thanks a lot Olly! For some reason it comes natural with the RASA data - never happened with my refractors. But then I also started using starless processing of the nebulosity which really helps to lift the nebulosity. Göran

I am fortunate enought to have my obsy at a dark site (SQM ca 21.5), but I get regularly light polluted by the moon 😄 and then I use an IDAS NBZ dual band (Ha Oiii) filter with the RASA8. Not very expensive. I assume it would work well with other light pollution too. Here is an example with 60% moon on 11 April. Even if you do not go for a RASA8, an IDAS NBZ may be worth trying. Cheers, Göran

Yes, maybe even +2👍 Its ability to hold focus is surprising. In my experience it holds focus as long as the temperature does not fall more than 3-4 °C. Many slower telescopes appear to be more temperature sensitive.

Yes I was also impressed by that one as it is exceptional and probably aquired under exceptionally good conditions.

I assume the ATIK has a HCG mode like the ZWO and QHY versions to bring down read noise and it must have a front window dew heater, but it is odd that I see nothing about any of this on the ATIK site or in the manual.