Hi. I'm trying to render out a sequence of frames but, no matter what file format I use, I don't have an alpha channel when I try to composite the footage. Can anyone suggest what settings I'm missing or how to go about creating alpha channels for my renders?
Thanks for any help anyone can provide.

What format are you using, that's odd, i always get alpha channel when i open the image in Fusion, have you tried saving in .exr format?

since almost every file format carries alpha channel (exept jpeg ) its seems more likely that you have problem with your shader or mantra setup (thought I have no idea how to force mantra not to render alpha - it could be some crazy plate depends of shading setup but it always there)

If you use your own shader make sure it treats alpha in proper manner (and not overwrites it somehow)

Second thing is… sorry for this stuff but are you sure you don't have alpha or maybe its just not premultiplied? Do you realy see only RGB channel? What compositing prog. are you using? Can you send a frame or simplified hip file?
In shake you have such command: “shake yourImage.tiff -info”. Also Halo gives you extanded info about plates… MMB on File COP