Alpha render pass

I’m trying to save out my animation with an alpha channel so I can composite it into some video, I’ve selected custom render passes and looked through all the render passes but I don’t see an alpha channel option. Can Unreal save out alpha channels at all?

Have you looked into the Unreal Composure Editor? I think you could achieve what you want using that.

EDIT: You might want to try the opacity option for your custom render pass.

Thank you, that may exactly what I need!

A more easy way is this one: