auto focus

[Jim Nelson]

Hi,

 

what is the problem when you use auto focus and the subject moves in the frame? What I mean here is that he always stays in the center of the frame but changes distances from the camera. Will the auto focus always focus on him properly or not? Will it focus smoothly or not?

 

 

thanks

[DavidFu]

Hi,

 

what is the problem when you use auto focus and the subject moves in the frame? What I mean here is that he always stays in the center of the frame but changes distances from the camera. Will the auto focus always focus on him properly or not? Will it focus smoothly or not?

 

 

thanks

 

 

You have to understand the computer inside the camera cannot distinguish what in the frame you are trying to focus on. There have been implementations of selective focus back on older Canon EOS film cameras where it would focus where your iris was looking and more recently on Point and Shoot cameras detecting faces. Both of these techniques are rather impractical in filmmaking. Your video camera is constantly trying to find focus, if the person moves, it cannot follow the person and will try to find focus again, and oftentimes this is not the effect you want. The best way to do this is to find the focus, then put the camera on manual so the focus does not change unless you change it manually. I understand your camera may not have manual focus, but that is difference between more professional cameras and household cameras.