Hallingskies

I think your best bet might be a Pulsar dome with a self-build housing. I remember seeing a cracking-looking obbo built along those lines in a recent thread on here. I think Pulsar also do different colours if the stark white is a problem.

Thanks. I fully understand that “stretching” an image brings up noise as well as signal. It’s one of the first things I got to understand when I started astroimaging about 15 years ago. What I don’t know is a way to measure or express a signal to noise ratio in a way that would allow consistent assessment of the noise in any given image. I realise the example I posted here is a bad one: IC 443 is a faint object even on a 600s sub, so the act of making it visible on a single shot will always bring up noise - it’s why we stack subs of course. But how can you objectively assess noise levels in individual subframes? How would you know if the background noise you see in any single sub is “natural” e.g. from haze or light pollution, or if it is down to some sort of camera fault? Would darks or flats always address the latter if it the problem was of a random, non-uniform nature, e.g. electrical interference?

First of all, this is a pretty spiffy first attempt. There's loads of good data there and low noise overall. In terms of colour balance I had a bit of a quick play in good ol' PaintShop (I don't do Adobe). It's your image and I don't believe in posting other folk's data (and I'm nowhere near as good a processing whiz as other folk here) but I found that 1) dropping the overall saturation a bit and 2) bending the low end of the blue curve a bit (Paintshop version attached) gave me a slightly more colour-balanced picture. You will be able to do the same things in Photoshop I'm sure. Have a play - you are very close to what I think is a very good image.

You are right, of course - I use Astroart and that applies an auto-stretch to displayed images. An unstretched image is very dark, as you say. It is hard to compare background noise levels between images without (literally) a level playing field. Unfortunately I have no idea what you mean by "single PI histogramtransform stretch to the first vertical line." Looking at my sub histograms though, there isn't any junk to left of the main "cliff" however - when I've had REALLY noisy images, there's loads of fuzzy stuff there. Don't know enough about the theory to know if the two are related, however...

Thanks. Just seen your wider field shot on the imaging forum - very good indeed! On the subs front, looks like mine are not as bad as I thought l from what I've seen above. I run my camera, filter wheel and dew heaters through a hub on the scope and I was wondering if the rat's nest of cabling was inducing some electrical interference that the camera was picking up.

Looks like my version (also taken last night) is a bit more stretched than yours. When I tweak your version in PSP it looks about the same as mine wrt "graininess". It'll be interesting to see if anyone "experienced" replies... The final effort didn't come out too bad with only 16 Ha subs (plus some RGB for the stars).

The subs from my ATIK 460 seem noisier than the ones from my uncooled SXV-H9, though I never used to go longer than 300s with that. Below is a sample from a single unbinned and unprocessed 600 second sub of IC 443 taken with the Atik. Sky conditions were excellent at the time. Is this a "normal" amount of "graininess"? Just wondered what other folk's subs looked like...

...and yet the FLO blog still carries other (excellent) equipment reviews... No one could ever question your credibility, but I can see how things could get awkward... I really like the idea of this product but will be waiting for others to take the plunge (and for some money to spend on it!).

Polar alignment must have been a bit tricky...

I look forward to your review....?

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Very nice, I’m sorely tempted, I’ve been thinking about one of these for a while. How’s the weather in the Wild West at the moment?

Adobe can go phooey. Their “rent” model is a rip-off. A huge +1 for Paintshop Pro IMO, it does pretty much most of what photoshop does, for a one-off licence. If only Steve Richards could write a PSP guide...

I recently tried IC 410 narrowband in Auriga and was pleasantly surprised how bright it was in Olll.

Back in the eighties I got moaned at for rebuilding our Ford Escort’s engine in our bedroom. Other halves can be so unreasonable sometimes. She did help me get it down the stairs and back in the car though.