Fisheye Mask?

[xgastudios]

Greetings,

I do allot of fisheye rendering using the dome cam, and was wondering if it would be possible to have the option to create a mask that would ignore areas of the image that I do not need to render. It would really speed up rendering time in my production cycles. I believe that the old fisheye option in the render scene dialog used to render with the mask.

Thanks

Matt