Shooting long exposures in RAW are super noisy. why?

Camara Photography, LLCCamara Photography, LLC Registered Users Posts: 82 Big grins
edited July 28, 2009 in Technique
I know there is a simple answer for this, but I don't know it... How come when I shoot long exposures (to get star trails) in RAW, I get a ton of noise. Not fixable in post kinda noise. Noise reduction is turned to "on". JPG is much better... why? any advise? shooting Canon 5d mk1.
www.CamaraPhotography.com

Comments

  • AndyAndy Registered Users Posts: 50,016 Major grins
    edited July 28, 2009
    How about some details? ear.gif We can't help without a photo to look at with Exif.
    Andy

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  • Camara Photography, LLCCamara Photography, LLC Registered Users Posts: 82 Big grins
    edited July 28, 2009
    Andy wrote:
    How about some details? ear.gif We can't help without a photo to look at with Exif.

    I don't have any examples (I deleted them), because they were so bad. but what I know is I was shooting RAW, 20 min~ exposure, ISO 200, no moon, around 12:00am, no other light pollution, temperature was around 50 degs, Noise reduction set to "on"... Result was extreme noise
    www.CamaraPhotography.com
  • schmooschmoo Registered Users Posts: 8,468 Major grins
    edited July 28, 2009
    I'm moving this thread over to Techniques for you! I don't have much advice except that I've had some bad experiences using noise reduction with low ISO like that, but it was a 30D for about a 30 minute exposure. I think if you do a search on Dgrin on this topic you'll find a lot of information that has been discussed in the past.

    Not that I do a lot of long exposure shots these days, but I had better luck taking multiple shots at shorter exposure times (5-10 min) and then stacking them in Photoshop.

    I hope this helps and good luck!
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  • pathfinderpathfinder Super Moderators Posts: 14,703 moderator
    edited July 28, 2009
    Most of the noise in an image is in the very lowest, darkest registers. If there is not data for a tone, because it was so dark out, then noise will be much more apparent because that is all that is left to record.

    As Schmoo says, the way most folks deal with this is to stack several frames, and then average the values - since the noise is random, averaging the pixels cancels out the noise.
    Pathfinder - www.pathfinder.smugmug.com

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  • AndyAndy Registered Users Posts: 50,016 Major grins
    edited July 28, 2009
    22 mins, ISO 200, Canon 5D MK2
    http://www.moonriverphotography.com/gallery/6222210_pXrvG#392544677_bPrt8-X3-LB The 5D can really do it well, I'd like to see some actual shots of yours next time... thanks!
    Andy

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  • pathfinderpathfinder Super Moderators Posts: 14,703 moderator
    edited July 28, 2009
    Lovely image, Andy. I escaped from the wind that evening, at Delicate Arch, too early for star shots.

    I shot a lot of frames with my 5D at Wright-Patterson recently, at ISO 1600 and found the files very nice.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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