Sony is to give away the specification for its E-mount lens interchange mechanism in a bid to encourage third-party lens makers to support its Nex compact cameras.

Launched in 2010, the Nex 3 and Nex 5 still cameras, and the Nex-VG10 camcorder, are compact devices. But unlike most compact cameras they have interchangeable lenses. Sony provides some of its own, but it wants other firms to do so too.

There's no reason to believe it wouldn't have shared the spec if asked, but it's telling that it's now willing to do so for free. That suggests it's worried too few lens makers will support E mount otherwise, and without their backing, E mount can be dismissed by some as a proprietary, Sony-only format.

Sony already offers an adaptor to allow Nex cameras to take lenses designed for its Alpha DSLR range.

Four lens makers, Carl Zeiss, Cosina, Sigma and Tamron, today all lauded the free release of E-mount spec. That said, none went as far as to say they will provide E-mount lenses themselves, though surely that has to be the outcome. ®