Rendering Alpha

[stevepickup]

Hello - Is it possible to render out a Geometry background but set the Geo containing it, so it does not contribute to the overall Alpha channel?

The trouble with using object layer id's and then creating and alpha from that is you get colour fringing on fine details.
Similarly if I just turn off the background and get the built in alpha.

Thanks
Steve

[stevepickup]

Scratch that looks like I can use layers to do it.