So, having come across a post on Flickr about a gentleman who was having problems with excessive hot pixels on his new 5d mkII at long exposures I decided that it’d be a good idea to test my camera out a little more extensively to make sure I didn’t have the same problem. Turns out I did have the same problem.
The problem is most evident when taking long exposures. In the sample image above I shot with the lens cap on at f5.6, ISO 100 and 30 second RAW exposure. Now, this is the tricky part; do not use iPhoto or Lightroom to view the image because the noise reduction software kicks in and you wont see it. You need to use the DPP software that came bundled with the camera and view a 100% crop on the image and scan the full image for dots. Usually you’ll get a couple in varying colours; red, blue and green are the most popular.
Of course you can use the cameras built in Long Exposure Noise Reduction custom function under the Image setting. This doubles the time it takes for an exposure and tends to soften the image. Using the LENR you’ll not see any of these dots.
There is an unofficial fix floating around but it’s not a dead cert. This didn’t work for me.