New scope, new shot (part 2)

bratislav (Bratislav) · #1 10-02-2018, 12:55 PM

Complete coincidence, scouts word

Another scope about to get into operation, unlike Louie's "quick and easy" go in with a wad of cash, walk out with goodies, assemble together using IKEA tools and shoot, mine being homemade never really is finished

But, after many nights of testing and fiddling around, it is finished enough for a proper test shot. What else than a faint nebula in Carina, which is now well placed and it can be imaged with necessary narrowband filters from my deep orange zone in Melbourne.
12" f/4 homemade Newtonian (with a tiny 80mm secondary), ZWO ASI 1600MM camera, Losmandy Titan. 45min total exposure.

Selected areas at 100%. Seeing was decent (around 1.8-2 arc seconds), helped with active mirror cooling. Can't wait for a night of good seeing!

Atmos (Colin) · #2 10-02-2018, 01:00 PM

Your stars look nice across the field which is what we all want so your fiddling has paid off

Looking at the crops, it appears that you’ve lost a lot of detail either in the noise reduction or in the dynamic range compression... or a bit of both.

bratislav (Bratislav) · #3 10-02-2018, 01:04 PM

Can you point at detail that is lost? You have to remember, this combination is 0.57 arc seconds per pixel, it is never going to look very sharp at 100% unless scope is placed in space ... or in Atacama.

atalas · #4 10-02-2018, 01:09 PM

Bratislav,the scope looks like It's performing nicely with good resolution but, It's really hard to evaluate how well with the amount of deconvolution used

Can you put up some new pics with no Decon ?

bratislav (Bratislav) · #5 10-02-2018, 01:17 PM

There's not that much deconvolution really.
Here's just a straight stack, with levels adjust only.

bratislav (Bratislav) · #6 10-02-2018, 01:38 PM

And a single 60s sub ...

(those ZWO 1600's have really low readout noise

)

atalas · #7 10-02-2018, 01:40 PM

Excellent!thank you....now I can say for sure that you've done a great job !

Now,on what Col mentioned about detail?sometimes It is just plain obvious that detail has been smeared and distorted....like is the case in the first pics you put up.

By referencing back to your linear stretch image as you process on, you can keep an eye out on not distorting structures.

Hope you get what I'm saying....I'm not great at explaining what's in my alternate universe mind

Oh,and by the way anything 2" and under is actually terrific seeing rarely comes around my parts of the woods.

Atmos (Colin) · #8 10-02-2018, 01:40 PM

When you compare the processes images against the complex stretch you can see the mottling and clumping caused by noise reduction. The simple stretch is a far superior rendition.
You have some wonderful data to play with

bratislav (Bratislav) · #9 10-02-2018, 02:04 PM

Fair enough! I've just used a default noise reduction in StarTools and didn't play much at all with settings (data was collected last night). Maybe I need more sleep ...

bratislav (Bratislav) · #10 10-02-2018, 02:21 PM

Quote:

Originally Posted by atalas

Oh,and by the way anything 2" and under is actually terrific seeing rarely comes around my parts of the woods.

Do you control your primary's temperature? You'd be surprised how things improve once you do. Fans are now mandatory in all my mirrored scopes.

atalas · #11 10-02-2018, 03:10 PM

Quote:

Originally Posted by bratislav

Do you control your primary's temperature? You'd be surprised how things improve once you do. Fans are now mandatory in all my mirrored scopes.

Yes of cause....huge difference in star profile when fans are running.

RickS (Rick) · #12 11-02-2018, 01:25 PM

The single sub looks excellent!

multiweb (Marc) · #13 11-02-2018, 04:27 PM

+1 Single sub really shows the optics quality.

You had lost a lot of fine details in the noise reduction with the original.

bratislav (Bratislav) · #14 11-02-2018, 05:25 PM

After not so much sleep (we had a wedding party to attend, I nearly forgot), I finally sat down and redid the processing, this time with absolutely minimal noise reduction and other sauces. So much in fact that now other problems are visible

I knew 1600 can suffer from fixed pattern noise, but I haven't seen any evidence of it; until now that is. The fix is actually quite simple - dither the subs religiously. Note to oneself. (I have actually specified the dither in SGP but realized the next day I forgot to enable it in the profile

)

So this is now a take #2, definitely not a final one, but I think despite the remaining noise it looks better. Of course this needs more subs, better seeing, proper dither, proper flats, but it is a test image after all ...

multiweb (Marc) · #15 11-02-2018, 05:26 PM

Now that looks very good indeed.

Atmos (Colin) · #16 11-02-2018, 05:46 PM

That is looking 1000% better!!
Very nice detail, very sharp.

bratislav (Bratislav) · #17 11-02-2018, 05:50 PM

Thanks guys!
I knew that optics is capable of very high resolution (both primary and secondary have been interferometrically tested to insanely high Strehl numbers). But having good optics is only a part of the story ...

Paul Haese · #18 11-02-2018, 09:30 PM

The later processing looks great. Very nice detail. Contrast levels are good too.

strongmanmike (Michael) · #19 11-02-2018, 10:49 PM

The latest lot look great Bratislav, nice

Quality of processing is inversely proportional to the square of ones level of attention, sleep deprivation... and inebriation

Mike

LewisM · #20 11-02-2018, 10:51 PM

Oh, so you process drunk Mike?