Author Topic: when is a dark not a dark....  (Read 1581 times)

Offline Peter

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when is a dark not a dark....
« on: 2015 June 26 08:34:31 »
I guess when it is taken by my Canon EOS1100D camera. I have used a custom white balance plus no camera white balance on the dslr format in Pixinsight. On both instances I have the following cr2 image. The exposure was 60s at 800iso and the camera is covered completely by its viewfinder and lenscap on also covered by a thick black cloth as I am taking these darks in daylight. The debayer is set at RGGB which is correct for this camera. Any idea how to arrive at a more natural colour one would expect for a dark? :o :o :o :o After posting this message and viewing the jpg it does not show the glaring colour that I see on my laptop. How do I send a jpg with the original colour of a bright glaring red? Sorted it now shows the proper image.
« Last Edit: 2015 June 26 08:42:54 by Peter »

Offline NGC7789

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Re: when is a dark not a dark....
« Reply #1 on: 2015 June 26 08:43:27 »
Can you put your CR2 on dropbox or somewhere so we can take a look. The jpg is basically meaningless for this evaluation (it does look red to me but dark). White balance should not matter much since it's just metadata in a raw file.

Offline NGC7789

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Re: when is a dark not a dark....
« Reply #2 on: 2015 June 26 08:45:14 »
ooh. You changed your image :). Is that viewed with STF? If so are the channels locked or unlocked? Since it looks dominated by the red channel I would expect it to look red. Again can you share your cr2 file?

Offline Peter

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Re: when is a dark not a dark....
« Reply #3 on: 2015 June 26 08:49:04 »
I will check my stf settings, I just tend to trust the default settings and just clickedon the stf icon. The reason I am asking about this image is that it seems to match exactly the red displayed on my lights which I always assumed to be light pollution. Cheers for the advice and I will drop it off. :D :D

Offline Peter

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Re: when is a dark not a dark....
« Reply #4 on: 2015 June 26 08:58:45 »
If I have done this correctly, believe me I can find thousands of ways to do it wrong, then the full .fit file can be found on dropbox as :

          https://www.dropbox.com/s/s6sf0fhkkd0340j/Single__0001__26C.CR2?dl=0

If this doesn't work then as explained it was a 1000/1 chance  :cheesy: :cheesy:

Offline NGC7789

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Re: when is a dark not a dark....
« Reply #5 on: 2015 June 26 09:07:38 »
Interesting. It doesn't look at all to me like it does to you. Here's my screenshot and DSLR_RAW settings. Note the STF channels are locked but it doesn't look much different unlocked. Also the histogram is not spiked like yours at all.

Offline Peter

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Re: when is a dark not a dark....
« Reply #6 on: 2015 June 26 09:27:59 »
Well NGG7789 you may have cleverly revealed my problem as I see your DSLR settings do not have the image flip, no black point correction or no highlights clipped. I tried you setting and am glad to report an image I expected to see in the beginning. You have certainly helped me find my way and I am grateful to you. Just out of curiosity why have you not used those settings indicated above?  :D

Offline msmythers

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Re: when is a dark not a dark....
« Reply #7 on: 2015 June 26 09:37:57 »
I also ran your image using the DSLR_Raw in Pure Raw. No white balance of any type. It is what I would expect. I debayered then STF linked and the histogram shows the color alignment as expected.


Mike

Offline NGC7789

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Re: when is a dark not a dark....
« Reply #8 on: 2015 June 26 09:42:11 »

Offline Peter

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Re: when is a dark not a dark....
« Reply #9 on: 2015 June 26 09:53:21 »
Thanks to you both, really glad that there are excellent people here who can not only help but are happy to do so. Again thanky you NGC7788 and msmythers