Is there a way to render an animation without ANY background? I just want the animated objects, no black background. I want to layer the animation over a video in Final Cut. I can do it by Luminance keying the black background(no sky) but I don’t want to do that.
Render with alpha on it should be interpreted in Fcp correctly.
Make sure that you render using a file-format that supports Alpha. JPG for example does not; PNG does; OpenEXR does. This channel is the correct source of the masking information that you seek.
For what it may be worth, I tend to use Blender for compositing and FCP for cutting.