AE Lock vs AE Lock With Hold
The new camera bodies from Canon (1D X, 6D, 5D III, 70D) all have a new feature called Auto Exposure Lock with Hold. I'll call it AE HOLD. This is similar but different than AE Lock. Depending on which of these two features you select, that feature can be selected by using the * button on the back of the body. Different bodies may have other buttons which may be programmed to activate it as well.
The crux of the change is this. Depressing the * button in AE Lock locks the exposure setting of the moment when you depress the * button. It only locks it for one exposure unless you continue to depress the * button or push the shutter button halfway down within 2 seconds of the previous exposure. That's not likely to happen, especially if there is any substantive time between exposures. If you want to lock an exposure for many frames over a period of time, you are probably out of luck. Enter AE HOLD (Auto Exposure Lock with Hold).
When AE HOLD is chosen (in the camera menus) instead of AE Lock, the * button is depressed and the exposure of that moment is preserved as the exposure for the camera. So far, that is the same as AE Lock. Either choice has an icon visible inside the viewfinder when selected. The difference is that in AE HOLD, the exposure is held until the * button is depressed a second time or the camera goes to sleep. Taking a photo does NOT cancel the setting. You may choose to keep the body awake for up to 30 minutes if you like.
With the outdoor track and field season nearly upon us, this feature can be quite handy for the action sports photographer. When shooting events like the pole vault or high jump, your perspective will often have the athlete set against a backdrop of sky. This can be by necessity or by choice to eliminate distracting backgrounds. That sky can throw off your exposure selected by the camera and compromise your image. If you have the time and opportunity, determining the desired exposure and shooting Manual is a great way to go. However, if cloud conditions are variable and/or you are on the run moving from one event to another you may not have the time to determine the ideal exposure and program it into Manual. Here's a shortcut that is fast, easy, and uses the new AE HOLD feature.
Imagine that you've just arrived at the pole vault pit. There is a bright sky with broken clouds and you want to photograph the competitors who will jump next. If you shoot Av, the bright sky will throw your exposure off. Try this instead. Using Av, aim your camera at a competitor on the ground who is in roughly the same direction and the same light as you will be shooting. Don't choose someone in shadow if your vaulter will be in sun. Try to avoid using someone with a totally black or white uniform as your exposure model. Press the * button for AE HOLD. The *H icon will appear in the viewfinder. Your exposure is locked and being held for you as long as the *H icon remains. Go ahead and shoot vaulter after vaulter with a constant exposure setting. If variable clouds/sun change the light, simple depress the * button a second time to remove the AE HOLD. Repeat setting the AE HOLD under the new conditions in the same manner as originally done and fire away.
Phil Zivnuska
If you have other applications for exposure hold, please share them with the group. PZ
Coming 1 April 2014, How to Photograph the Long Jump