“The lens’ AF is slow and won’t hold focus, how can I fix it?” “At times, the lens seems to be searching for the subject. What setting should I use?” These were the two most commonly asked questions this week sent in for my GearHead posts. I didn’t answer them there because, these aren’t gear problems, it’s what we politely call, pilot error. First, the lens contains the motor that moves the element(s) or element group that physically focuses the image. It’s the AF engine in the camera body that tells that motor how and when to move. So it’s not the lens not holding focus or searching, it’s the camera body signal, or rather lack there of, causing the issue. When working with photographers in the field and they are having these issues, 95% of the time the problem is their panning, not their gear (and oh my, how they howl with that answer. It CAN’T be them!).
This shot of a C-47 was shot with a D4s / 200-400VR2 handheld at 1/20, f/32, ISO100! At that shutter speed, to repeat, 1/20, if I had to manually focus, I’d still be in pain. We have to rely on that camera’s AF system which means we MUST do a couple of things, constantly, all the time. First is understand that the camera’s AF system, no matter the brand, needs three things to focus. It needs contrast, strong diagonal or vertical lines. And when shooting a moving subject, we must give our camera/lens rig a sturdy, stable and SMOOTH platform following that subject. So when I hear problems of “the lens not holding focus or searching,” I have only one answer. Practice, practice, practice … time to Pan!