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Old 05-06-2016, 02:29 PM
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Shiraz (Ray)
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Shiraz is offline
Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,820
Originally Posted by Slawomir View Post
No doubt the supplied dark has extremely low noise, but 8 electrons variation will in some cases (imaging faint nebulae) need to be corrected with darks when using the camera for 5-minute or longer subs in narrowband imaging. Also, since noise goes up with signal, even after applying darks there will probably be somehow higher noise left in those brighter areas?

I am sorry if I am too particular and also too inquisitive, but I like doing my homework before buying. Also, I am specifically interested in this camera's performance in purely narrowband imaging because of intense light pollution in my area plus I simply like narrowband imaging

EDIT: Will need to measure background signal in my subs.
Crikey, there is no need to apologise for digging into the detail - too much stuff gets glossed over and then comes home to bite after a purchase is made. The narrowband potential of this camera could be very interesting and it would be great to know how significant the possible "glow" is compared with your sky signal.

edit: just scaled the darks that I do have. Most of the image has negligible dark current at -15, but two fairly small areas have some "glow", that would amount to about 20 dark electrons at the brightest point over 10 minutes (~0.03 electrons/s). That will give excess noise of up to 4.5 electrons RMS in one corner (for comparison though, that much excess noise is a bit less than the read noise from my 694). The rest of the dark has effectively no dark current. I don't anticipate that this will impact significantly on my images, but agree that about 3% of the camera is not quite as good as the rest of it for narrowband. Must measure at 10 minutes rather than scale and also try it at a lower temperature to see if that helps.

Last edited by Shiraz; 07-06-2016 at 09:48 PM.
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