Jargon buster

Gn (Guide number) This is a measurement of flash power, quoted in metres or feet, usually at ISO100. The maximum distance for a correct exposure equates to the Gn divided by the aperture. For example, a rating of Gn 24 would give a maximum shooting distance of 3m at an aperture of f/8.

Wireless connectivity

This goes beyond a simple optical sensor for using off-camera flash in manual mode, and includes an infrared link for TTL metering communication. Some flashguns add RF (Radio Frequency) wireless communication.

Info screen

A rear screen is fitted to all the flashguns on test, apart from the Nikon SB-500. The Metz flashguns incorporate touch-sensitive screens for the adjustment of settings.

On-board controls

You can typically apply changes to flash settings from menus in the host camera, but it’s often quicker to use the control panel on the flashgun.