Nikon SB-900 Speedlight - £325/ $506

Nikon's pro flashgun, the SB-900 has a beefy maximum output of GN 50. It launched with exotic features such as simplified master/slave wireless operation, automatic detection for cameras with different image sensor sizes, three different lighting pattern options, and extras such as coloured filters and a diffusion dome, though these features have now trickled down to the cheaper SB‑700.

Other similarities include a thermal protection system, with a visual temperature display on the back.

However, the SB-900 adds repeating flash for a strobe effect, plus an auto-aperture mode for balanced exposures. Nikon has just announced a replacement, the SB-910.

Performance

Working seamlessly with Nikon cameras, i-TTL metering proved entirely reliable in our tests. And while the recycling speed from a full-power flash is one second slower than with the SB-700, it's still fast, at four seconds with NiMH batteries. Overall, the SB-900 is the ultimate choice for professionals, but the SB-700 is better value for amateurs.

Flash output

The SB-900 matches the Metz for outright power, and it proves really consistent throughout the whole range, right down to 1/64 power.

Aperture reading at 1m
Theoretical: 34
Measured: 32

i-TTL exposure accuracy

You'd expect supreme accuracy from Nikon's top professional flashgun, and that's what you get, although it's matched by the SB-400 and SB-700.

i-TTL exposure accuracy
Measured: -0.2EV

Colour accuracy

The fantastic power ouput of Nikon's biggest flashgun is matched by good performance in our colour accuracy tests across the spectrum.

Colour accuracy
Measured: 18

Image quality verdict

For accuracy in both manual and i-TTL modes, the SB-900 is a standout performer, and colour accuracy is impressive. It's the top pro choice.