Thank u for responding. I am shooting a movie in which several characters will have an eye replacement. Now if they just stare straight ahead I can easily use Andrew kramers effect. But if they turn there head from left to right they effect doesnt work as well. My question is how would I fix this problem. Now I know I would probably need a 3d tracker but Im on a tight budget. I know voodoo is free for windows users but I cant find something like that for mac.