John Cornwall, via email
Why are tiny white crosses appearing on images from my D3x?
Matt says… ‘Hot pixels’ occur when a pixel on the sensor of your Nikon receives excess charge. This afflicts most cameras after an amount of time. You can ignore it, as the size of the hot pixels usually makes them invisible when the image is viewed at 100 per cent, or set up a Photoshop action to clone the pixel out.