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Old 11th April 2011
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Ian Ian is offline
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Re: Problem with bulb exposure + remote

Noise Reduction is pretty essential for long exposures and works regardless of ISO speed. Basically the longer the exposure the higher the chance of random pixels producing the wrong colour or brightness - so-called hot pixels.

With Noise Reduction after the long exposure shot has been taken, it's stored in a memory buffer and the sensor is refreshed and left sensitised for the same length of time as when the shot was taken, but with the shutter closed. The same hot pixels will appear (they are independent of exposure by light) and the exposed image is compensated for according to the hot pixels recorded. This is also called dark frame subtraction.

But it does mean the camera is tied up for as much time again after the original exposure has finished and it may indeed look like the camera has frozen up. So if you do a 10 minute exposure, you will have to wait for a further ten minutes for the dark frame subtraction process.

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Last edited by Ian; 12th April 2011 at 12:32 PM.
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