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12/07/2005 02:15:11 AM · #1 |
Alright, so ive noticed on a couple of shots of mine that i get a strange instance of pink noise on one edge of my pics when i do really long bulb exposures (and not on shorter ones.. but like 15 min long etc...) It happens in different locations so i know its not the place...
Is this something others have noticed...? I use the digital Rebel.. could it be something internal to the camera.. the lens..? Below is a pic with it, although i tried to minimize it here. (on the right edge) Thx for help/tips.]
JS |
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12/07/2005 04:22:44 AM · #2 |
Ya know, I never heard of it on the 300D, but the 1D suffers from purple edges at long exposures.
Basically the circuitry heats up too much and that heat affects the sensor. My guess is that you have the same issue.
though honestly, at 15 min, I'd expect most any camera to give out.
Max |
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12/07/2005 01:08:47 PM · #3 |
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12/07/2005 01:17:57 PM · #4 |
In the situation like you posted above (the stars) what I have found works best is to take multiple shots of around 5 minutes each, that overlay them together in photoshop.
This shot is 9 photos of 5 min. each totalling aprox 45 minutes:
If you still see the overheating effect drop it down to 4 or 3 minutes, whatever works.
Good Luck!
Aaron
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12/07/2005 01:41:46 PM · #5 |
The edge heating effect can also be greatly reduced by dark frame subtraction. You'd need to do this manually with the 300D. Google it, you'll find a lot of information on the technique. I do agree that combining multiple, shorter exposures is a great way to improve quality on very long exposures; besides the reduced edge heating, there's a very significant benefit in reduced random noise as well. Specifrically, random noise is reduced as the square root of the number of exposures, so for instance, using 4 exposures results in half the noise :-)
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