wimvb

How many subs in the stacks? Not 3, I assume?

I may have a go this evening.

22 hours ago, Piero said:

This can also be found in the second hand market.

I bought it a month or so ago, directly from the publisher. Don't buy from the great river company, they charge 3× the price for some reason.

55 minutes ago, Kon said:

Yes that pole has to go! 💥

Either that, or move the observing chair. 😉

Double post

12 hours ago, ollypenrice said:

The MN190 deserves a makeover with quality hardware around the optics. 1000mm FL and F5 is right on the money for galaxies and nebulae.

😁

It just happens that a year ago, I decided to upgrade the stock focuser with its wobbly extension tube and ordered a FeatherTouch, with adapter ring. This is supposed to be a drop in replacement. Unfortunately, the FeatherToch turned out to be vapourware. So this summer I've installed an Omegon focuser, which was a drop in replacement (except for a thin shim, because it was slightly too low).

But I digress. Back to the original discussion...

1 hour ago, tomato said:

just one scope for your DSO imaging, the RASA could be the best choice

Couldn't agree more.

On 23/08/2023 at 20:46, tomato said:

I was looking at imaging scales the other night and noticed that my current small galaxy camera, the ASI 178 with a RASA8 gives an imaging scale of 1.24 arcsecond per pixel binned 1x1. So last night I put it on the RASA and went after NGC 891. I scaled 94 mins of subs with the same integration taken with the Esprit 150 and the same camera binned 2x2 so imaging at 0.94 arcsecond per pixel. After the same process workflow, here are the results:

RASA8

and the Esprit 150 version:

Also I have just noticed that there is now a superior alternative to the 178 available, the ASI678 which has smaller pixels (equivalent to 1.03 arcseconds per pixel), lower read noise and no amp glow. It is only available in OSC, but using a mono camera on the RASA to get a colour image would be tedious to say the least. I think I will take a punt on one of these cameras and see how good small galaxy imaging could be with the RASA.

I always thought that if I had to go down to just one imaging scope it would be the Esprit 150, but now I'm not so sure...

Nice images, but if you used any form of sharpening, the comparison isn't relevant anymore. (The image taken with the Esprit looks sharpened.) The amount of sharpening during deconvolution eg, depends on snr. Better would be to show the images with just an stf stretch applied.

Btw, with the youngest generation of sony sensors, one may start to question the need for cooling, or the use of calibration frames, for that matter. It'snjust a shame that ZWO put the power/data connectors on the wrong side for their non-cooled cameras.

3 minutes ago, michael8554 said:

Who writes this stuff ?

Marketing, with the help of chatgpt, I'd think. Never read the blurb, Michael. Wait for Cuiv to do a review. 😉

2 hours ago, Clarkey said:

Is this not the same principle as night vision kit (and other similar sensors). Very high gain but very noisy. I remember covering this at college 30 years ago. Not sure how it would affect well depth and bit depth though.

Yes, the principle is the same, but 30 years is a very long time in tech development. A lot has happened in those years. Like any discrete event process, you can't predict when an avelanche event will happen, only how often on average. So there is shot noise. They've probably come up with means to refuce that noise, using clever measuring methods.

The Eq3 has a capacity of 5kg, or just the 150pds by itself. The problem with this mount is that it has no load carrying bearings. In stead it relies on teflon washers and the black grease it comes with. I think that with a sturdy tripod and new motors, the load capacity is only marginally affected. But, use it as is and gain experience. In a year or two you’ll be in a better position to specify what you want. The eq3 is a nice grab and go mount for a lightweight setup, with maybe a 60-70mm refractor, so very well something you may wish to keep.

Small collimation errors are barely noticeable. Small focus errors are barely noticeable. Small guiding errors (if you're imaging) are barely noticeable. But if you have all three, you have a fuzzy image.

It really is a wonderful sight, isn't it?

So, mint in box. Definitely save it till 2060

So, if I interprete the results correctly, @han59:

• Cooled is better than not cooled, regarding both noise and hot pixels
• It's beneficial to use (matching) darks even if you don't cool your camera
• Darks should match lights within a few degrees.

Two questions come to mind:

1. How many degrees difference can there be between lights and darks? (At 26 C, 3 degrees seems ok; does that hold at -10 C as well?)
2. How critical is temperature for amp glow removal (the other reason we use darks)?

Excellent rework. With this example you may just put camera modifiers out of work.

Wow! A stunning, bold image with lots of details if you zoom in.

That's a very colourful Gandalf, neither gray nor white. Excellent image.

15 minutes ago, JeremyS said:

Can you drop the late please. It hasn’t started yet 🤣

Do you mean that summer is late this year? 😜

In theory, yes. But focus can shift during a night, due to temperature change or simply due to slipping. That's why you need to check focus every now and then.

Thanks @gorann. Just a few more weeks ...

15 hours ago, peter shah said:

Possibly because the Heart has higher contrasting detail....this is a much softer object and a lot more effort needed to show its features.....which you have done brilliantly BTW, those delicate dusty tones are sublime 

You are right of course about the objects being different. But I wasn't satisfied with a few details, mostly near the core of ngc1931, where I had lost colour. Fixed now. I'll put the improved version in the original post shortly

53 minutes ago, gorann said:

Amazingly deep for only being 6 hours at f/5, particularly in the Ha. Close to what I would expect from a RASA or Epsilon image.

Thanks Göran. To paraphrase a certain song from the Beatles.

"Mak is all you need"

😜

Late summer reading.

1 minute ago, peter shah said:

another cracker....beautiful

Thank you, Peter. For some reason, this image was harder to process than the Heart nebula I posted yesterday. Here, I had to work hard not to burn out the core of ngc 1931, while also keeping the delicate shades in the rest of the nebula and in ic 417.

The Spider and the Fly. Reprocessed data from March 2022. The central region of ngc 1931 is quite bright, and reminds me of the core of M42. This nebula also has a small group of stars in the core, similar to the Trapezium stars in M42. The core is home to a dark nebula, DOBASHI 4431

Almost 6 hrs worth of HaRGB data captured with my MN190 and ASI294MM

Original version:

Improved version:

2 hours ago, windjammer said:

What an absolutely brilliant trick!  I had a go on your image and it works a treat! (hope you don't mind).  I will put this in my toolbox.

(Don't mind at all.) I'm glad you find it useful. SCNR removes one of the primary colours, red, green or blue. If you invert an image first, it removes the corresponding complementary colour, cyan, magenta, or yellow. In this case, the image didn't have much bright and solid red in it, as many Ha images tend to have. That's why it was easy to remove the dominant red/magenta and get something which looks like a Hubble palette.