This is a very rough shot of IC2631. It needs a lot more hours of exposure but I like the composition and potentially this could be a good area for a mosaic.
Taken with the QSI683 WSG-8 on Sunday night at -25C. I am happy to report that it held this temp at 62% all night. Composed of LRGB it contains two subs in each colour and luminence. 20 minutes subs for Lum, 15 minutes subs for the colour.
There is still quite a bit of noise but given that this is a very faint object the noise is only present in the dust regions. That means this camera is producing very little noise at that temp and will also mean that triple the time the noise should just about be gone.
Pretty impress with this new camera. It now fills my requirements perfectly.
Wow, that is tight. I like the framing, though would go just a smidgeon wider if I had the option.
I think a mosaic of this area would be stunning.
What scope are you using with the camera?
Wow, that is tight. I like the framing, though would go just a smidgeon wider if I had the option.
I think a mosaic of this area would be stunning.
What scope are you using with the camera?
Not much choice Peter. This is with the TSA102 and a reducer. That is around f5.6/7 and focal length of 571mm.
Steve, yes more data makes for a stunning image. The data was very clean coming out of the camera, but I had to stretch this so much just to get it bright enough and I really think it needs to be brighter still to have impact.
Louie, I am chomping at the bit especially since this object is about mid way in its rise to the meridian and it being so low and close the roof of the observatory. I am please with the cirrus coming through already and that bodes well for the finished image.
A great start Paul. I shot this one a few times now and last time with the AP140. It is very dim.
I am not sure 20 min subs is the way to go with an 8300 chip on a fast refractor though. There are about 20 stars in your image that are blown out.I usually limit them to 5 minutes with the ML8300 to protect those bright stars from being overblown. With low read and dark noise cameras like this one and the FLI there is theoretically no gain to 20 minutes. With a noisy camera yes there would be.
Mike thanks for the correction. I knew the darker cloud is molecular but had though the faint grey stuff was cirrus. Learn something new all the time.
Your light bucket ought to gobble this up nicely. My tiny little scope needs hours and hours to keep up.
Greg, I don't think the stars are overblown as I think I did not take much care with controlling the bloat as I normally would do. I did a fair bit of stretching and neglected to take care of star bloat. I take your point though on sub length, but think that depth would be missing if you only going 5 minutes in sub length. I feel there is alway something to be lost when using short subs to gain a few stars from blowing out. Signal strength and overwhelming the background noise I feel is more important in the scheme of things. Many people seem to use short subs, but there are a few of us that dare to be different. Mathematically I am sure short subs are correct, but I do like the extra detail I get from longer subs. Perhaps I should put this to a test one night just to settle this.
It would be worth a test. Its not a big point but its worth talking about.
The trouble with the overblown stars is not that you've over curved them or anything, that data is now gone in the highlights. These CCDs with small wells spill over to surrounding wells or the surrounding wells in the weaker diffraction rings swell up too much.
I guess I see contrast more as the 16803 has 100,000 electron wells versus around 25,500 for the 8300. I didn't see these as a problem on your RC longer focal length shots because the narrower image spreads the flux over more pixels than the widerfield (I think I have that right).
If your tracking is super which your is then the gain in sharpness from less tracking error also helps give the image more snappiness I have noticed in my own 8300 images. I have quite a few using the TEC180 at F7 and there are too many with overblown bloated stars that tend to damage the image.
I would not say those overblown stars are wrecking the image just that instead of being overblown whitish stars they could have been nice features with nice colours. Perhaps at the expense of deeper detail?
I wonder what others' experience is on ideal exposure length. Marcus switched to 15 minute subs. I always used 15 minutes for subs but switched to 10 mainly because of the need for rounder stars not for overblown stars. I don't see any loss of reach or detail in later images using 10 minutes. Narrowband is different because Ha etc are so noisy they need longer exposures.
Nice work on the dark neb Paul, this is a target ide like to select, not the whole lot but a specific piece. I note that the subs are very noisy does QSI allow you to set your own offset and gain or is it a factory preset? I only say this because my images have all been without darks and bias working at -20 degrees.
As for sub lengths I have been running out to 900 and 1200 shots on a regular basis with the 254 and that is at F4.72 as you could well imagine this isn't a slow scope and does pull down the images pretty quick. I have noticed once I set my gain and offset properly, it stopped blowing the stars out super quick with my latest tarantchula being a good example, the subs i used for that are 600 seconds with such a bright object this should have blown out well and truely but it has not (I will admit there it isn't far off full well depth!).
Im not sure if its a refractor thing but the newts stars tend to be quite tight without star reduction techniques but they have a lovely coloured glow around the bigger stars that other stars and nebula shine though.
It would be worth a test. Its not a big point but its worth talking about.
The trouble with the overblown stars is not that you've over curved them or anything, that data is now gone in the highlights. These CCDs with small wells spill over to surrounding wells or the surrounding wells in the weaker diffraction rings swell up too much.
Yeah true but how many images out there don't have a few blown stars? I could deal with this a bit better and maybe take some short subs to cover the blown data. That will get the best of both worlds.
Quote:
Originally Posted by gregbradley
I guess I see contrast more as the 16803 has 100,000 electron wells versus around 25,500 for the 8300. I didn't see these as a problem on your RC longer focal length shots because the narrower image spreads the flux over more pixels than the widerfield (I think I have that right).
The RC images I thought were worse but I could be wrong there too.
Quote:
Originally Posted by gregbradley
If your tracking is super which your is then the gain in sharpness from less tracking error also helps give the image more snappiness I have noticed in my own 8300 images.
Yes my guiding is pretty damn nice. Not bad for a supposedly stuffed mount (someone elses comments to me). It has made a huge difference to my images have great guiding.
Quote:
Originally Posted by gregbradley
I would not say those overblown stars are wrecking the image just that instead of being overblown whitish stars they could have been nice features with nice colours. Perhaps at the expense of deeper detail?
Yeah that can be quite distracting. I see your point and agree.
Quote:
Originally Posted by gregbradley
I wonder what others' experience is on ideal exposure length. Marcus switched to 15 minute subs. I always used 15 minutes for subs but switched to 10 mainly because of the need for rounder stars not for overblown stars. I don't see any loss of reach or detail in later images using 10 minutes. Narrowband is different because Ha etc are so noisy they need longer exposures.
Greg.
Yes I am always interested in what other guys (of gals) are doing as far as length of subs.
Quote:
Originally Posted by bmitchell82
.... I note that the subs are very noisy does QSI allow you to set your own offset and gain or is it a factory preset? .
Brendan I can change the gain from high to low and that might well make a difference.
Quote:
Originally Posted by tilbrook@rbe.ne
Wow!!!
What did they say in War of the worlds, oh yeah, something about watching earth with envious eyes.
Man I've got a long way to go!!
Great image.
Cheers,
Justin.
Thank you justin but this is just the start of this image. It was part of the initial test of the new camera. I am sure I will produce something a lot better.
Quote:
Originally Posted by Rigel003
Congratulations on the new camera. Looking forward to lots of super cooled, noiseless images. How's the download time?
Not as fast as your FLI Graeme. Reasonable at around 4 seconds or so for 1x1 binned images. For focus it is superfast.
That looks awesome Paul, and the stars are very tight. It will be a great image once finished.
The skies have also cleared over here and mine is gathering luminance right now at -30C while I experiment a bit with PHD settings for the Lodestar. Exciting times
Peter I have a second hand PME that had some slight issues due to maintenance not being performed correctly, but all it fixed now. Well I think so anyway.
Rolf, wow -30C what percentage of power? That is my plan during winter to use -30.
Rob yes very happy with performance of all things at present. All working great. I just have to get focusmax sorted now. Been stalling a bit on using it, despite having the unit for a few months now.
Sub length is always an interesting subject. Everyone has a different set of experiences and each is validated by their images. Never discount that someones experiences will work better than your own. I always read and wonder if I am doing the right thing. I bet many others think the same thing from time to time.
