Silver Peso

[beren]

Amazing, finally got a reasonable night at last to hit the driveway and set up kit. Spent much of the early evening catching up on visual and Jup {err seeing not up to it} before trying out a SBIG ST2000xcm for the first time. Had a smooth run setting up the cam and getting the inbuilt guiding going, thought NGC253 might be a good first light practice target. First tried sequences of short subs but found longer was better, image attached is a single 20 min, unfortunately didn't have the time to capture more or go longer. Used CCDsoft for cam control and IP3 for processing, going to need plenty of practice with the processing side :P surprised how noisy the cam is, plenty of hot pixels considering the cold night temp and the ST's -20c temp regulation.

[iceman]

Wow,really nice Stuart. Lovely the colour and detail in the disc.

Nice job indeed and great to see more images from you!

[Garyh]

That is very nice for one sub!
Nice and detailed.
cheers

[Dennis]

Hi Stuart

That is a very nice image of NGC253 – just lovely!

I hear you about the one shot colour cameras! I used my ST7 at the Qld Astrofest and then had the opportunity to use Gerald’s ST4000XCM on the last night.

I shot a 10 minute exposure of M16 with the Mewlon 180 at F9.6 (Reducer/Flattener) and I was very surprised at how dim and noisy the single frame was. I then decided to bin 2x2 (no colour, just B&W) and even with x4 the flux, I felt the image still looked a little noisy compared to the ST7?

Some of this could be attributed to my lack of processing skills or whatever, but certainly the OSC cams do not have as high a QE as the monochrome.

Cheers

Dennis

PS -However, I did have a severe attack of agoraphobia! The size of the ST4000XCM chip and its TC237 guide chip (I have the TC211) almost made me fall off my chair!

[strongmanmike]

Looks pretty good Beren, what scope/mount was it taken with?

It is hard to guage the consistency of your pixel noise given that you only took one light frame thus used no combination process. Did you subtract a dark/s? If so and there are still lots of spurious pixels there may be something wrong with the camera?

My KAI11002 chip (mono interline) based camera had an issue when I first received it last year, my dark noise was inconsistent from frame to frame and didn't match my lights wich were also displaying random variations in pixel noise so I couldn't produce a clean calibrated image without dithering (moving the telesope slightly) between light exposures and then median combining both the darks and the lights. It turned out that the chip needed to be "re-clocked" so it went back to FLI for a quick visit.

My darks now match my lights and my lights (at -35C) are much cleaner too, no dithering is required and I can use "sum" (the best method I believe, if your subs are clean and consistent) instead of "median" or "sigma" combine in preprocessing now, no further pixel work is necessary in pre or post processing other than cosmic ray and the odd random pixel removal.

My impression is that a lot of people using the SBIG KAI11002 camera feel it of paramount importance to dither and median or sigma combine because of unclean final images otherwise, but I don't know if this is from the same issue I describe or whether your issue is related?

Just a thought..? :)

Mike

[Striker]

Great stuff Stuart.

All these nice DSO images make me want to get back into imaging so much but I have to keep reminding myself NO it's time for to image pelicans....lol

[jase]

Nice work for one sub Beren. Interesting composition. Hope to see more for the finished product.

No dithering Mike? You're kidding me right, not even a single pixel? You got yourself a Class 0 chip or something. The Class 2 11k I've got has a few column defects. These pixels are dead, i.e. don't collect any photons whatsoever. Obviously whether I'm cooled at -10 or -40 makes no difference to these defects. Same applies to hot pixels. Dither is the only way to overcome these shortfalls.

[strongmanmike]

No, I don't dither my images. I have no deffects that I can see..?

As I said when I was getting the unmatching pixel problem before the re-clock the only thing that would give me clean calibrated images was to dither (manually) and then median combine lights and darks. Now after the service job I simply sum (ie "add") my lights and this leaves only a handfull of odd pixels really that I sometimes don't even bother removing (or at least I forget to :P).

Mike

[beren]

Cheers Mike, Gary, Dennis, Tony {hey great to hear from you mate :thumbsup:},Mike, Jase appreciate the feedback gents :).


Yeah Mike mount and scope used was a EM-200 and FSQ-106, short FL for the target but NGC253 has some nice stars to guide on in the FOV. I guess its not a great test to guide at 500mmFL but had no problems except with the guide cam I couldn't get a clean image with it set at 1x1bin for some reason :shrug:had to set it at 2x2. I'm unfamiliar with CCDsoft for image processing so I used Images plus {which handles SBIG files/bayer at capture WB} to handle both the 15x60sec{20 separate darks} subs and the single 20 min sub. Both exhibited both a sprinkling of hot pixels, in CCD soft the program has a repair function for this but I couldn't figure out how to use it with the finished TIff image from IP {greenhorn blues :P}. Still working on some light boxes but will try bias frames and dithering and see how that goes. One thing that did surprise me was the effect of light pollution/sky glow seemed pretty good at 20 min, I thought it would have been blown out for sure .

[bluescope]

Nice image !

My ST2000XCM also has lots of hot pixels but they are easily sorted either in CCDOPS ( Utility/Filter Utilities/Kill Warm Pixels ) or in DSS as well. I'm not sure about CCDSoft ... still haven't come to grips with that software as yet.

I should be receiving my William Optics FLT-110 F7 Triplet Apo next week and will no doubt be shooting NGC253 again, weather permitting ... can't wait to see fov etc should be similar to your FSQ-106.

:thumbsup:

[Matty P]

That is very nice for only one sub. Nice detail.

Well done. :)

[RB]

G'day Stuart, very nice shot mate.
Good to see you imaging again.

:thumbsup:

[beren]

Thanks Steve, Matty, Andrew :)


Gday Steve first congrats on the new scope coming.....on the second outing the hot pixel phenomenon wasn't to much of an issue :shrug: I haven't used CCDops, I more familiar with CCDsoft and the copy of Images Plus I have handles SBIG files. I have a lot to learn about processing :P

[bluescope]

Yeah 2 weeks is a long time for me to wait for the scope .... I'm an Aries ... I want it yesterday !
I've read really good reports about the FLT 110 so looking forward to it !

Keep at it mate !

:thumbsup:

[beren]

:) I've seen one in the flesh, jaw dropper looks, had a tour looking around the Carina region and the views where superb. Have you got a IR filter to use with your ST2000 and the new scope ?

[bluescope]

Yes, Baader UV/IR 2" and 1.25", 1.25" Baader LPR UHCS, 2" IDAS LPS2 plus I'm getting the WO FLAT68 field flattener and 2" WO Quartz Dielectric Diagonal with the scope. Should have it pretty well covered visual/imaging wise but there's bound to be something else down the track like WO bino viewer when I finally get to dark skies, wouldn't be any point here really .... I live in hope.

:thumbsup: