Not sure if this link is any use..............dave https://forums.cgsociety.org/archive/.../t-606259.html Thanks for the reply, dave. That's the exact technique I've been using. I got it from a gnomon pixie dust sprites tutorial. It works well...just not when using mental ray to render. Mental ray seems to ignore the colors of the sprites, and just assign the current frame's image to all of them. I'd use hardware rendering, but I also need to use depth of field, and HR doesn't support DOF. I can't use software render because it won't see sprites.