Quote Originally Posted by Agilulfo View Post
I'm not sure to understand why you don't rely in the DOF button of your camera.
Depends on the lens and the focusing screen. It you've got a lens that's faster than f/2.8, the standard focus screen doesn't show the true DoF, it shows the DoF of ~f/2.8. That means with an f/1.4 lens, unless you're stopped down beyond f/2.5, your actual DoF is thinner than it appears in the VF, and you can't accurately judge focus.