How many times have you taken that perfect shot, only to find later that your subject was out of focus and other areas of the photo were sharp? Are you trying - and failing - to create those awesome, shallow depth of field shots that really isolate the subject of a photo? You're not the first or only victim of these problems and there can be several causes. What's more, even the most expensive, sophisticated equipment won't solve these problems for you. Fortunately, almost all modern digital cameras have a feature that can help. In this tip, I'm going to explain how and when to use the focus lock.
What's in the Name?
Your camera manual may refer to this feature as a focal lock or with a different term, and you may find it in the index under "Focusing" as "Recompose". No matter what it's called, using the focus lock is actually a matter of prefocusing and recomposing your shot. If you've been following our tips for beginning photographers, you've read the term "prefocus" before. If not, you can find out more about it here.
When Should you Use the Focus Lock?
The most concise answer to that question is, "anytime you're using autofocus and want to be sure one part of your photo is in focus." Obviously, that covers a lot of territory and that's the point. More specifically, you'll want to use it when your subject isn't going to be lined up with an active AF point in your viewfinder when you press the shutter release. That can happen in almost any shooting situation and at any focal length.
How to Set up for It
Before you use the focus lock, you'll want to be sure your camera is in the correct AF mode. You can utilize any of the focus points in the viewfinder, but in most cases, the center point is the easiest to use and it will be one of the higher precision points in the camera, too. Set your camera to allow you to manually select the AF point and set only the central one as active.
Next, make sure the "servo" focus mode is turned OFF. Any mode that uses the focusing servo will adjust the focus when you move the camera. Select the "One Shot" or equivalent focusing mode.
How to Use It
You can use the focus lock when you're shooting through the viewfinder or using the camera's LCD, but the procedures are slightly different. Note: You may need to adapt these instructions to suit your particular camera make and model, but they will apply in general to most popular brands and types.
- Zoom to frame your shot: If you're shooting with a zoom lens, line up your camera for the final shot and zoom your lens to the focal length that frames it properly. DON'T READJUST THE FOCAL LENGTH AFTER THIS STEP. This step will apply whether you're looking through the viewfinder or at the LCD.
- Using the Viewfinder: Point your camera at the main subject, so that the active focus point in the viewfinder is centered over the most critical area, for instance, the eyes of your subject for a portrait. Press the shutter button halfway and allow the camera and lens to focus. Wait for the focus spot to flash and/or the beep. Then, move your camera to reframe your shot, holding the shutter button at the halfway point. When you have the correct framing again, press the shutter button smoothly and fully without releasing it.
- Using the LCD: Without moving the camera, move the focusing window in the LCD to cover the main subject. If necessary, increase the magnification of the LCD (NOT THE LENS) and/or move the window again for a better view of the details you want to focus on. When you have the view you want, press the shutter button halfway, wait for the LCD and/or beep to verify the focus, then smoothly press the button completely.
The LCD method is particuarly useful when you're using a tripod, since it doesn't require you to move the camera after initial framing. To avoid camera shake, use your camera's self timer and let go of the shutter release buton after pressing it.
NOTE: Many DSLR cameras offer a "back-button focusing" option that lets you use a button on the camera back to lock your focus setting. On many models, using this method will alloe the camera to maintain the lock for multiple exposures. Check your owner's manual for this feature, as it may often be more convenient than the shutter button method.
Manual Focusing
While you may not be able to "lock" the focus in manual mode, the same techniques apply. You can shift your view to the main subject for careful focusing, then recompose the shot for the same results. When you're using the LCD, the ability to increase the magnification in the areas of your subject can be a great aid to focusing.
A note about autoexposure: When you're using the focus lock, it's important to remember that when your camera is in standard autoexposure metering modes, the exposure settings will also be be calculated when you press the shutter halfway. If you want to set your exposure for a different part of the scene, you'll need to use the autoexposure lock in conjujnction with these techniques. That subject will be covered in another tip, but you can read up on it in your camera manual.
Practice using the focus lock and enjoy the improvement in your photos!