reflections and alpha

Is there a way to make an object completely transparent other than what it reflects?

Say I have a sphere and a plane with raymirror, and I want the plane completely transparent save it’s reflection of the sphere.

welll…if the plane is completely transparent, it will not reflect anything, not even the sphere. To answer your question, in the Materials panel under Raytracing is the RayTrans button. Enable it and set accordingly. Ensure Ray tracing is turned on in the Render panels.

Yeah, I figured it was impossible, I was just hoping there was a way. Thanks anyway.

that being said, the render pass Refl should give the reflections of things. I don’t know what you want to do, so cant really help much. Do you mean like a piece of glass reflecting something, but being clear otherwise? Like in Lost when the doc was in the cell and talking to the girl??

I don’t know if this will work, but you could try doing a pass using the raymirror and a pass with it being transparent and combining the images in the compositor. For the raymirror pass make sure it’s not reflecting any sky.