Mental Ray 3.2 and Alpha Chanel
 

I don't get any alpha channel on Mental Ray. The option for RGB and Alpha seem to be greyed out in my Global Rendering otpions.. Anybody can help ?

That's very odd. I can show alpha on mine.

i see it but I can't check it or uncheck it... can you ?

Maya 5.0

Well here is how it works.

There is an option called Framebuffer Attribute in the MR Render Global Editor, Play with the settings and you ll see how alpha channel integrates in Photoshop. Pretty neat actually !