I was with my son last Sunday having fun shooting landscapes when two butterflies visited us and started hovering around us. My son wanted to quickly focus on them and shoot their motion in the air. He was on Single-Point Autofocus mode so I told him you will not be able to quickly focus, you have to change your focusing mode... we missed the shot!
Sometimes the light is perfect, the moment is right, but your photo is blurry! Why? The reason might be that your camera is not focusing properly or you did not choose the right autofocus mode.
But first, with every composition, you need to ask yourself if:
- Your subject is still;
- Your subject is moving; or
- Your subject is still but might move quickly
If your subject is still, the most commonly used method and the ‘standard’ setting on your camera would be single-point. Just choose AF-S for Nikon or One Shot for Canon. When you press your shutter half-way down your camera focuses until the picture is taken. As long as your subject maintains it's distance from the camera, your photo will continue to be in focus. This is the method to go-to if your subject is not moving (landscape, portraits, events, table-top, product photography, etc.) Your camera will beep when focus is achieved so you know you are good to go. Furthermore, this mode allows you to choose your focus point because you know where you want to place your subject.
In single point autofocus you can focus on your subject by placing it in the center of the image, recompose while maintaining your finger halfway pressed, then pressing the button full way down. Your subject remains sharp if the distance remains the same. Very useful for the rule of thirds...
Now, if you are shooting a soccer game or a drift race, the problem is your subject is moving, what to do?
If your subject is moving, the engineers have come up with a continuous autofocus (AF-C for Nikon or AI Servo for Canon). This mode let's you continuously autofocus on your moving subject. The camera will do the rest i.e. continual adjustment while you hold down the shutter button.
To put this in practice, imagine you are shooting your son riding a bicycle. Place the Auto Focus (AF) point on your son and slightly press the shutter. As long as you are pressing the shutter, the autofocus will continually adjust to your subject, keeping it in focus as it moves. When you are ready to take the shot, press the shutter all the way and the camera will focus on your subject for a sharp image.
Now what if you are shooting kids and toddlers playing in the park? Uuuugh. The most difficult and challenging focusing issue. This is where the engineers have provided a third option called (AF-A for Nikon or AI Focus for Canon). This mode starts as a single shot AF when you lock in on a still subject, but once that subject starts to move it changes automatically to continuous auto focus. Clever isn't it. So if your subject remains still, you can focus and take the shot, and if your subject decided to move you can seamlessly focus continuously and shoot. AF-A / AI Focus offers really the best of both worlds.
But remember when you cannot autofocus to check the following troubleshooting checklist:
- You are too close usually 30 cm for the majority of lenses unless you have a macro lens.
- Your focus point does not have enough contrast to assist the autofocus mechanism.
- You have accidentally turned off that AF switch on the lens.
Next time you wonder why your photo is blurry, check if you are using the right autofocus mode. I hope this helped clarify a bit your camera manual. Go out and test it why don't you on moving cars, and school soccer games.