Fixing Random Hot or Dead Pixels
April 9, 2011
Most DSLR video guys would never notice this problem, but for photographers, it’s something that happens pretty often. If you’ve been doing long exposures or dark images and have been seeing some stray / hot / or dead pixels, here’s a tip to try before sending the camera in. This has been implemented in DSLR cameras for a very very long time and is a way to remap these pixels (hide the bad ones). Is this some type of hack job? Actually, no. Many cameras will do this automatically on start up or shut down, and it’s almost impossible for any chip with millions of pixels to be 100% perfect. Here’s how you do it.
First remove any lens on the camera and place the body cap. You can actually do this with a lens, but you’re more prone to ‘light leaks’. Place the DSLR Body cap on and for safe measure, you might want to cover it again with a dark cloth, tshirt, or dark blanket. You basically want to keep any light from leaking into the camera while performing the cleaning.
Go to the Menu > Select Sensor Cleaning > Manual Clean.
The Mirror flips open, the camera basically should expect every pixel to be completely black, but if it’s finding some white or red ones, it should remap them. After about 30 seconds, turn the power off on the camera. Now go out and test out your long exposures or dark imaging to see if those same hot pixels still show up.
Here’s another tip. If you plan on buying or selling a DSLR, you can also perform a test against your sensor to see these stray or hot pixels. You can leave a lens on the camera, but just cover it up completely to prevent light leaks or sit in a very very dark room. Set the lens to ‘Manual Focus’, set ISO to the lowest like 100, shutter speed to say 1/60th, and aperture doesn’t really matter. We’re not doing long exposure here, because we don’t want to confuse a Dead pixel with ISO noise. Next, take a picture. The picture should come out ‘mostly’ black, but this test will show some stray red or white hot pixels (unless it’s already been remapped which is OK). If you’re shopping for that camera, and you can’t seem to get rid of those stray pixels, consider if they are so bad they would render your work useless. Again, since HD video doesn’t actually use all the pixels by the time it’s resized down, Video shooters may not notice something like this as easily.
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