Visual Adventures » Autofocus Tip – Dealing With Interference

Autofocus Tip – Dealing With Interference

Posted October 22nd, 2015 by Mike Hagen | Photography | Permalink

In celebration of our new book titled The Nikon Autofocus System, I have another photography tip for sports and wildlife photographers.

If you have ever photographed your children playing sports, then you’ve no doubt come across the scenario where another player on the field gets in the way of your shot. Typically, what happens is that you are tracking focus on your daughter when another player crosses between you and your daughter. This of course causes the camera’s autofocus to jump to the other kid, resulting in a missed shot.

In this photo sequence, I’m tracking AF on the player with the ball. The other player closer to the camera is about to get in the way. Change your focus tracking menu and add a long delay to deal with this issue.

Nikon and Canon have a solution for this in the menu systems on most of their higher-end cameras. The Nikon menu item is called Focus Tracking with Lock-on and can be found in custom settings menu a3 or a4. The Canon menu item is called AI Servo Tracking Sensitivity and can be found in menu AF 1 on cameras like the EOS-1D X and 5D Mark III/5Dr.

The purpose of these menus is to help the camera better track focus on subjects that are moving through busy or cluttered environments. These menus let you adjust the amount of time the camera waits to refocus on a new object that passes between the main subject and your camera.

Nikon’s focus tracking menu is titled Focus Tracking with Lock-on.

Canon’s focus tracking menu can be found in AF 1. It is titled Tracking sensitivity.

Let’s say you’re photographing a team sport, and your intention is to photograph a specific player such as your daughter. The first step is to set your focus servo to AF-C (Nikon) or AI servo (Canon) so you can track movement.

Now, suppose your daughter is running on the field and you’re doing your best to track her as she moves. At some point during the game, another player is bound to run between your camera and your daughter. This presents a dilemma for your camera’s AF system. Should it immediately jump to the new player, or should it let that player pass while maintaining focus on your daughter?

In this example since you’re trying to photograph your daughter, you want the camera to let the other player pass by while maintaining your intended focus distance on your daughter. To accomplish this, set the menu item to a long delay, which allows temporary objects to pass by, thereby keeping focus on the original subject.

With the long setting, the autofocus system waits approximately 1.5 seconds. In other words, if the interfering player stands between you and your daughter for less than 1.5 seconds, the autofocus system will keep the focus distance on your daughter’s position. If the interfering player stands between your daughter and the camera for more than 1.5 seconds, the autofocus system will refocus on the new player.

Most higher end Nikon cameras have up to six settings for this menu item while the Canon cameras have 5 settings. In my experience, photographers either need to set menu item for a long delay (1.5 seconds) or they wanted to set for no delay. The available settings are as follows:

5 (long): About a 1.5-second delay
4
3 (normal): About a 1-second delay
2
1 (short): About a 0.5 second delay
Off: No delay; the camera refocuses instantly if another subject comes between you and the main subject

Another example of when to use this setting is when you photograph a lion on the Serengeti Plane of Tanzania. Suppose you are tracking a lion as it walks through tall grass. You’re doing your best to keep the autofocus point on the Lions eye when it saunters behind a tuft of grass. In this situation, you don’t want the autofocus system to jump to the tuft of grass; you want it to stay focused on the lion. Again, set the menu to long delay to tell the camera to ignore the grass as it passes by the autofocus system while you track the lion.

I encourage you to try these settings on your own to see what works for you.

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Want to learn more about autofocus on Nikon cameras? Check out our brand new book titled The Nikon Autofocus System, Mastering Focus for Sharp Images Every Time.