Originally posted by cpk When using back button focusing and AF.S, what settings are required to prevent exposure if the subject is not in focus? Or is this out-of-focus exposure prevention possible only if using the shutter button to focus?
On a K3 go to AF Setting Menu and select Focus-priority. I've never tested it to confirm that it works with back button focus. I always wait for focus confirmation, whether you are focused on your subject is dependent on you. I just tested it and Focus-priority doesn't work for back button focus, I removed the lens cap and pushed the shutter button and it took the photo out of focus. So you will get exposure and lots of them depending on your drive mode settings.....LOL.
I guess the focus priority setting is for those folks with a "happy" shutter button finger to prevent the finger from going past half press. Logically thinking using the back button and getting focus confirmation should prevent the photographer from missing focus, unless you are old and shaky like me