Sigma EF-610 DG ST

£100/$165 www.sigma-imaging-uk.com

the ef-610 is rated at a huge GN61 power rating, making it the most potent performer here. Our testing backs this up, and the illumination is even, with only a trace of vignetting.

There’s TTL compatibility with Canon, and the zoom head can focus the flash burst to suit focal lengths from 17mm to 105mm. The head also boasts a full range of tilt and rotation, but both axes are locked with individual release buttons which can interfere with quick head adjustments.

But compromizes have been made. The plastic hot shoe stings considering the cheapest rival flashguns sport a metal mount, and you can forget about a backlit LCD. Flash intensity is limited to just two power settings: max, and 1/16th. Lastly, the EF-610 can’t be used as a slave flash as there’s no form of wireless triggering.