A flash which reacts to the output from another flashgun, usually one mounted on a DSLR or similar camera. By firing simultaneously, the scene can be illuminated by a number of sources.
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.