iMac won't download Nikon D610 NEF files

Folks

Bought a nice new Nikon D610 but my Mac won't download the NEF files, just the JPEGs. I can do it just fine on my laptop running Vista (I'll wash my mouth out later), so there's nothing wrong with the camera.

Has anyone a work round such as loading the camera as a drive - which I'd prefer to do anyway.

Cheers - Andy!!!