Rea l world meets lab
We looked for the distance each flash could cover, as well as how smartly it performed
■ All functions, features and firing modes of the flashguns were tested. To check output power, each flashgun was fired at each setting throughout its entire range of manual settings. This was repeated at zoom settings of 24mm, 50mm and 105mm (FX), where available. A flash meter was used at a distance of one metre, and the resulting light readings were then converted to give a Gn number at ISO100, measured in metres.
We also checked for flash exposure accuracy, using TTL rather than TTL-BL (Balanced fill-flash) mode. For this, we photographed a neutral grey card, which should produce a spike at the centre of the histogram, and then calculated the amount of over- or under-exposure in +/-EV (Exposure Value) steps. Finally, we measured the recycle speed after a full-power flash, using both alkaline and NiMH batteries.