Defective pixels which are permanently ‘off', and show as dark dots in the image. This should not be confused with light-shielded black pixels, which line the peripheries of a sensor and are used to monitor dark current.
On sale: 4th Jul
If you're in the market for a lens, don't miss our complete guide to buying a lens, with 8 pages of tips and advice to help you make the best decision. Also in this issue we put three of Nikon's best DSLRs up against each other to find out what you get for spending more money. Plus much more!
Which of the new cameras announced so far this year are you most excited about?
It may take 15 minutes for the system to update.