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Old 12-08-2008, 05:12 PM
beren
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Cygnus rufus

Another attempt with a ST2000XCM on M17 last night, 3x25min through a FSQ-106. Even though the moon was bright I was eager to go longer in sub times and see what could be done Had some teething problems earlier on in the evening with the cam fogging up or something {recharged the desiccant that same day } but eventually got things rolling but kept the temperature at -5. With that higher temp I seemed to have the hot pixel problem again and has introduced artifacts into the attached image {I think}. Ah yes lots to learn

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Old 12-08-2008, 05:57 PM
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EzyStyles (Eric)
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very nice shot. colours looks spot on.
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Old 12-08-2008, 06:24 PM
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Why only -5 ?
The camera can go around -30 ambient with air cooling only so you have lots of head room. I usually shoot between -16 and -20 during these winter nights. You will still get hot pixels but you will get a better response from your chip as regards signal to noise.
Go on ... crank up that fan. Manual recommends running at between 75-80% capacity from memory.



p.s. Image looks good.
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Old 12-08-2008, 07:58 PM
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That's really nice looking nebulosity and lovely colours Beren in a great FOV. I know you are still in the testing phase so look out for when you start pushing deeper because there is plenty of nebuloisty in that frame!

All you need is to do flats, or are you already doing these just not for this shot? Even basic snaps of a piece of white paper illuimnated with a white light in front of the scope will help in this case, if you don't want to do real flats. If you have already tried flats, sorry for stating the obvious . The moon has of course accentuated the vignetting so it may be hardly noticable in moderate exposures like this with no moon?

I agree, I would have thought you should be able to happily go colder..?

Nice

Mike
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Old 12-08-2008, 08:16 PM
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Very nice.

Greg.
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Old 12-08-2008, 08:43 PM
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Ive found this object really difficult to image and achieve that colour Beren ... and you've done it. My ST2000XM seems to be a whole lot noisier than your one shot colour one. I know this flies in the face of the data sheets, however I have viewed a couple of your pictures now and it seems that this is indeed the case.

Nice picture
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Old 12-08-2008, 09:53 PM
beren
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Thanks Eric,Steve,Mike,Greg,Jeff

Yeah Steve early in the night when setting up the autoguiding during the calibration step I had trouble getting guidestars from frame to frame. I had the temp set at -25 originally, lowered it down to -5 and things got better. During the course of the night the guiding seemed spot on but had to require the same guidestar after each sub Next time out I'll go lower

Mike no flats yet but hopefully soon I'll rectify that with a light box from Astro handy {saw the link from your site }.

Jeff I'm sure with more practice etc the mono cam will clearly show its superiority


Cheers again
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Old 12-08-2008, 10:38 PM
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A nice image there - really nice colour. I took the liberty of running it through gradient exterminator - hope you don't mind.

Cheers, Marcus
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Old 12-08-2008, 11:03 PM
beren
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Thanks Marcus, there you go I forgot to use GX



Also took 3x10min subs, when combined with the 3x25min subs I had to to crop some of the image due to the stacking aberration, might as well post it.
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Old 13-08-2008, 12:14 AM
jase (Jason)
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Nice work. 25min subs for an F/5 scope is certainly letting those pixels bleed. Image shows good depth and pleasing colour rendition. Wouldn't get too worried about temp. providing you've got darks/bias to match. I've found cooling wont do much for hot pixels. This is simply a CCD defect, along with dead pixels. Nothing image processing can't remedy anyway. Look forward to seeing more.
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