I know you can do the same thing with certain scopes on a gun. A guy told me to cover half the scope with a quarter and look through. When I looked through you couldn't see any of the quarter
In Las Vegas a few years ago of took a couple of shots of a white tiger through a chain link fence. The tiger was about 20 feet away from the fence line. I was able to focus on the tigers face making the fence disappear. I used a Sigma 70-200 2.8 lens. Made for a nice image.