lovelifey: [Photography] How to Avoid Blurry Photos by Choosing the Right Autofocus Mode

The post How to Avoid Blurry Photos by Choosing the Right Autofocus Mode appeared first on Digital Photography School. It was authored by Lynford Morton.

Sometimes the light is perfect, the moment is right, but when you get home, you find that your photo is blurry. Arrgh!

Why are your pictures blurry? One obvious reason is that your camera isn’t focused properly.

You see, while today’s cameras and lenses can help you quickly take sharp images in a wide variety of situations, you must first choose the right autofocus mode.

So here are some questions to help you diagnose any blurry-photo situations – so you can choose the correct autofocus settings, consistently!

Are you using the auto-area autofocus mode or the single-point autofocus mode?

Who gets to decide your focus points?

That’s what you’re deciding when you choose between the auto-area AF mode versus the single-point AF mode.

With an auto-area autofocus mode, your camera decides what it should use as your focal point. It usually decides based on what looks most prominent in the viewfinder or is closest to the camera.

Is this a bad thing?

Well, it can work if your subject is obvious and there are no potential distractions. But what do you do when you’re trying to focus on a smaller subject within the frame?

For more control, you choose a single point autofocus setting.

The single-point mode allows you to choose your specific autofocus point (check your camera’s manual if you aren’t sure how to do this).

After all, only you, not your camera, know where your subject is – and where you want to position it within your composition.

(Also, note that your camera offers several additional AF area modes – but it’s a good idea to start by choosing between the auto-area mode and the single-point mode.)

Is your subject moving?

Most DSLR cameras give you four basic options for autofocus settings: single, continuous, auto, and manual.

To help you choose the right option, ask yourself, “Is my subject moving?”

Then, based on your answer, read the relevant advice below:

No, my subject is not moving

If your subject is not moving, choose “AF-S” on your camera (though this mode is referred to as “One Shot” on Canon cameras).

AF-S acquires and locks the focus as soon as you half-press the shutter button. If your subject stays at the exact same distance from the camera, your photo will be in focus (and you’ll be able to keep taking photos and can expect them to be in focus, too). If your subject moves, then your photos will be blurry.

In other words:

Your subject has to be stationary for AF-S to work. In fact, the shutter won’t fire if your subject is moving and your lens can’t acquire focus.

AF-S also allows you to recompose. Let’s say the autofocus point is in the center of the frame, but you want your subject positioned close to the edge. As long as you maintain a half-press on your shutter button, the focus will remain sharp on your subject.

Then you can move the camera slightly left or right, positioning your subject away from the center of the frame.

Yes, my subject is moving

If your subject is moving, use continuous autofocus (“AF-C” on most cameras, though Canon calls it “AI Servo”).

With this mode, you can place your autofocus point over your subject, and the focus continues to adjust while you press the shutter button. This keeps your subject in focus as it moves.

For example, if someone is riding a bicycle, you can place the AF point on your subject and half-press the shutter button. As long as you’re half-pressing the shutter, the autofocus will adjust continuously, keeping your subject in focus as they move.

When you’re ready to take the photo, depress the shutter completely, and the camera will fire a sharp, in-focus image.

No, my subject isn’t moving, but it might

A third option merges the functionality of the single autofocus and continuous autofocus modes. This hybrid mode (“AF-A” for Nikon or “AI Focus” for Canon) works differently depending on your camera.

However, AF-A always involves some sort of automatic switching between AF-S and AF-C modes, based on whether your camera perceives a moving subject or an unmoving subject.

With AF-A activated, you can focus on an unmoving subject exactly as if you are working in AF-S. But as soon as the subject moves, your camera will switch to AF-C and begin tracking.

Make sense?

For some photographers, this is the best of both worlds and allows you to deal with erratic subjects that repeatedly move and then stop suddenly (i.e., birds). However, you’ll often lose the ability to focus and recompose, because your camera may attempt to refocus based on the position of its autofocus point – so make sure to bear that in mind.

My autofocus just isn’t getting it right

You always have the option of turning off the autofocus function and choosing the manual focus setting.

When should you do this?

Well, if your camera is having trouble detecting your focus point, it might be more efficient to focus the camera yourself.

Note that you can turn off your autofocus on accident. So 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 focus without meaning to. 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?

I’d recommend you consider these solutions:

You might be too close. Try backing away. If you are too near your subject, the camera may not be able to focus properly.
Your subject might not have enough contrast. Your image needs to have some contrast for most autofocus systems to work. If you try to photograph a solid sheet of white or any single-colored wall, most autofocus systems will struggle. Why? Cameras use differences in colors and tones to determine their focus. If a camera 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’s 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 gives you a blurry photo. Make sure your shutter speed is faster than the equivalent of your focal length. For instance, if you are zoomed out to 100mm, your shutter speed should be 1/100s or faster to avoid camera shake.
You have motion blur. If your subject is moving quickly and your shutter speed is too slow, the photo will end up blurry – so make sure you’re using a fast-enough shutter speed to freeze all motion in the scene.