Photography class 7 - manual focus and auto focus modes
Photography for beginners
You camera has two distinct modes to choose from. Auto focus and manual focus.
Auto focus is a beautiful invention and allows us the ability to capture things that we never thought possible 30 years ago! New DSLRs focusing systems can have 153 focus points are capable of focusing in -4ev! That's basically the ability to focus in near darkness! Admittedly this is more on the flagship models, but it'll filter down to pro-sumer and consumer cameras in no time.
Like most of the other automatic features on your camera, auto focus doesn't always get it right. You may want to focus on a leaf on a tree, but the camera may choose to lock onto the bush in the background. Or it may hunt around the scene looking for a point to lock onto, only to choose the complete wrong subject. Frustrating, right?
Single shot/continuous focus mode
Single shot auto focus is the best option for stationary subjects. The user gets to move the focus point around the focus area and choose a point to lock focus onto. Once focus has been achieved, you can press the shutter button and you should have a sharp photo, with the point you selected, in sharp focus.
Continuous focus is the best option for moving subjects. The lens focuses continuously, and by default, you are able to take a photo at any time, even if the subject isn't in focus.
A third option that some camera bodies offer is a hybrid of these two settings. The camera detects when a subject is stationary or moving, and selects the focus mode for it. I personally stick to choosing the focus mode manually.
AF area mode
The AF area mode dictates on where the camera itself will look to focus. You can select between single point, a cluster of points (continuous focus mode) or make all of the focus points active. Each focus mode gives the option to select the focus point yourself or have the camera choose it automatically. Different camera models will have slightly different settings.
When the camera has focused, you'll see a focus confirmation dot in the viewfinder. It's even there when you're focusing manually!
The very first thing we want you guys to do is take control of the focus point yourselves. We want you to find your focus mode setting and change it from auto, to single point. It'll usually be depicted as a single square in the middle of a focus area. Once you've done this, look through the viewfinder and scroll the focus point area by using the d-pad. Now find something to focus on. Move the point over that subject and half press the shutter. Take the shot. Find something else to focus one, and repeat the process above. That's all the is to single point auto focus!
After you've had a little experimentation with single point auto focus, change to continuous focus mode. We want you to find a slow moving subject and choose a focus area mode. Follow to subject through the scene and get a feel for how the focus point flicks through the viewfinder to track the subject. Take a couple of shoots and review them in the back of your camera. Are they sharp? Did the camera focus on the subject? Now switch to another AF area mode and repeat.
Choosing a slow moving subject will give you time to observe the focus point moving in the viewfinder as it tracks the subject. It'll also give the camera a better chance to acquire perfect focus and get a sharp photo.