I tuned up my PMX mount at my dark site and sacrificed some imaging time under superb conditions to get it right.
It was time well spent as the PMX is now cranking out probably 1.5 arc second guiding.
Using a super sharp AP140 and 5nm Ha astrodon filter and 20 minute subexposures at 1x1 binning on a FLI Proline 16803 this image is perhaps the sharpest image I have ever taken. This and the LRGB image have stars as low as 1.2 FWHM. I know Martin probably gets this routinely at Sierra Remote but in Aussie its not so common.
I have had a look at both the color and this the BW version, on a personal preference this is the one I like, the subtle detail in the Ha stands out so nicely, looking at them side by side, whilst the color is pretty, that superb finesse of detail somehow just doesn't appear so obvious.
I have had a look at both the color and this the BW version, on a personal preference this is the one I like, the subtle detail in the Ha stands out so nicely, looking at them side by side, whilst the color is pretty, that superb finesse of detail somehow just doesn't appear so obvious.
Thanks Clive. Yes I agree. I reprocessed the colour version to give it more impact and get those lovely Ha details to stand out more. It is posted as an alternative now on the colour image thread.
It looks more violent now. The area gives the impression of being very chaotic.
I thought 2-minute subs were sufficient with this nebula, but from your photo I see I need to go for longer subs: http://www.astrobin.com/full/148715/C/
I have had a look at both the color and this the BW version, on a personal preference this is the one I like, the subtle detail in the Ha stands out so nicely, looking at them side by side, whilst the color is pretty, that superb finesse of detail somehow just doesn't appear so obvious.
Quote:
Originally Posted by Slawomir
Great image Greg, love the detail and sharpness
I thought 2-minute subs were sufficient with this nebula, but from your photo I see I need to go for longer subs: http://www.astrobin.com/full/148715/C/
Thanks Slawomir.
I think it depends on the CCD used. The KAF16803 has over 100,000 electron well capacity as opposed to the Sony ICX814 which has about 12,000. So you'd have to monitor the brightnesses. Take an image and check the ADU numbers as you move the cursor over bright parts of the image. You start seeing a lot of 65,535 that means you are overexposing.
There's no set exposure length but individual best exposure for that particular CCD being used.
I think it depends on the CCD used. The KAF16803 has over 100,000 electron well capacity as opposed to the Sony ICX814 which has about 12,000. So you'd have to monitor the brightnesses. Take an image and check the ADU numbers as you move the cursor over bright parts of the image. You start seeing a lot of 65,535 that means you are overexposing.
There's no set exposure length but individual best exposure for that particular CCD being used.
Greg.
I checked and maximum ADU numbers for this nebula in 2-minutes subs in my photo are under 5000 units (except for bright stars that are already at maximum ADU), so it looks like I could go for much longer subs - will try it one night and see if I can capture fainter nebulosities like in your image
I checked and maximum ADU numbers for this nebula in 2-minutes subs in my photo are under 5000 units (except for bright stars that are already at maximum ADU), so it looks like I could go for much longer subs - will try it one night and see if I can capture fainter nebulosities like in your image
Thank you Greg for explaining that.
Its a question of how many stars are you willing to have overexposed.
You could mask out the stars in a narrowband sub if you are doing a narrowband RGB image and use lighten mode to let the RGB stars come through.
Trial and error I think is the key. 2 minutes is certainly very short for narrowband. These are 20 minutes and John Gleason uses 40 minutes with an FSQ.
congratulations greg that is a wonderful capture - well done, you have to be so happy with that - i agree defiintely worth getting a print of that and hanging it somewhere prominent!
Nothing beats a full toned, detailed , sharp monochrome image and yours ticks all the boxes.
Worth printing and framing!
Ross.
Gee thanks Ross.
Quote:
Originally Posted by strongmanmike
I agree Ross, great image Greg
Cheers big man.
Quote:
Originally Posted by RickS
Fantastically sharp, Greg!
The seeing, the optics, the guiding all were top notch and sometimes they all work together (well you've got to make it work).
Quote:
Originally Posted by rustigsmed
congratulations greg that is a wonderful capture - well done, you have to be so happy with that - i agree defiintely worth getting a print of that and hanging it somewhere prominent!
regards,,
Russell
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Thanks very much Russell. Ha in this area is quite dramatic.
