A Post By: Lynford Morton
Sometimes the light is perfect, the moment is right, but when you get home you find out that your photo is blurry. Arrgh!
Why are your pictures blurry? One obvious reason might be that your camera isn’t focused properly. Today’s cameras and autofocus lenses can help you quickly take sharp images in a wide variety of situations, provided you choose the right autofocus mode.
Here are some questions to help you diagnose any situation and choose the correct auto focus setting
Photo by Lynford Morton
Are you using the Auto-area autofocus or Single-point autofocus selection?
Who gets to decide your focus point? That’s the question you are deciding with this option. In an Auto-area autofocus, your camera decides what it should use as your focal point. It usually decides based on what looks most prominent in the viewfinder or closest to the camera. This might work when your subject is obvious and there are no potential distractions.
For more control, choose a Single-point autofocus setting. That mode allows you to choose your specific auto focus point (check your camera’s manual if you aren’t sure how to do this). After all, only you, not your camera, knows where you want to place your subject.
Is your subject moving?
Most DSLR cameras give you four basic options for autofocus settings: single, continuous, auto or manual. To help you choose the right option, ask yourself, “Is my subject moving?”
No, my subject is not moving
Photo by Lynford Morton
If your subject is not moving, choose “AF-S” for Nikon or “One Shot” for Canon. This mode locks in your focus based on the distance to your subject. As long as your subject stays at that distance, your photo will be in focus. Your subject has to be stationary for this mode to work. In fact, your camera will not take the photo if your subject is moving (or it cannot lock focus).
This mode also allows you to recompose. Let’s say the autofocus point is in the center of the frame, but you want your subject on one side or the other. Keep depressing your shutter button slightly, and focus remains sharp on your subject. Then you can move the camera slightly left or right, recomposing with your subject out of the center of the frame.
Yes, my subject is moving
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If your subject is moving, use continuous autofocus (AF-C for Nikon or AI Servo for Canon). In this mode, you place your autofocus point over your subject, and focus continues to adjust while you hold down the shutter button, keeping your subject in focus as it moves.
For example, if someone is riding a bicycle, place the AF point on your subject and slightly depress the shutter. As long as you are pressing the shutter, the autofocus will continually adjust to your subject, keeping them in focus as they move. When you are ready to take the photo, depress the shutter completely, and the camera will focus on your subject for a sharp image.
No, my subject isn’t moving, but it might
A third option merges the functionality of the single autofocus and continuous autofocus. This hybrid mode, (AF-A for Nikon or AI Focus for Canon), starts out as a single auto focus. Your camera won’t focus until you lock in on a stationary subject. Once you have your subject in focus, you can take the photo as you would in a traditional single auto focus mode.
If your subject starts moving, however, the autofocus releases and continues to track your moving subject. It gives you the best of both worlds. One note of caution, I have noticed at times, if you recompose a stationary object quickly in AF-A mode, the camera can be fooled into thinking the subject is moving and release the autofocus.
My autofocus just isn’t getting it right
You always have the option of turning off the autofocus function and choosing the Manual setting. If your camera is having trouble detecting your focus point, it might be more efficient to focus the camera yourself.
How about the opposite situation? You turned off your autofocus by accident? Every now and then, when your camera can’t seem to focus, and you don’t hear the motor searching back and forth, check to see if you selected Manual autofocus by accident. This can happen more frequently than you might think.
Other issues to consider
What if you set up your autofocus properly, and the lens still won’t focus? Try these considerations:
- You might be too close. Try backing away. If you are too near the subject, it might prevent the camera from focusing properly.
- Your subject might not have enough contrast. Your image needs to have some contrast for many autofocus systems to work. If you try to photograph a solid sheet of white or any single color, most autofocus systems will struggle. Why? The camera compares adjacent pixels and when one is different, it uses that point to determine its focus. If it can’t find any contrast, it can’t focus.
- You might have an extremely shallow depth of field. In this case, your autofocus is working, but the depth of field is so shallow, it is hard to tell that your subject is in focus.
- You have camera shake. When you depress the shutter, you move the camera. If the shutter speed is too slow, the camera picks up that movement, and it looks like a blurry photo. Make sure your shutter speed is faster than the equivalent of your focal length. For instance, if you are zoomed to 100mm, your shutter speed should be 1/100th of a second or faster to avoid camera shake.
Why is your picture blurry? If the answer is in your autofocus, your fix could be as simple as choosing the right setting.
Do you have any other autofocus tips or comments you’d like to share? Please do so below.