When you look through your camera viewfinder, you see multiple Autofocus points.
When you half press your camera’s shutter button, some of these points will light up to lock onto the subject being captured.
The number of possible autofocus points depends on the camera.
UNDERSTANDING AUTOFOCUS POINTS
Autofocus Points are what the camera uses to focus on a subject.
As a photographer, you have complete control over the available autofocus points.
Automatic AF Selection and Manual AF Selection are the two main settings found in almost every modern DSLR.
Automatic Autofocus Points Selection
This does not require a lot of technical explanation.
When selected, your camera will automatically decide which Autofocus points to use.
Leave the choice of focusing point to your camera and it will illuminate the selected point in the viewfinder when you press the shutter release to focus.
Automatic AF Point selection works great in many different types of photography.
For me, it works great with birds in flight photography.
Manual Autofocus Points Selection
DSLRs also allow you to select the focusing point yourself.
Such a feature comes in handy if the autofocus isn’t detecting the subject automatically, or you’re using One Shot autofocus and don’t want to reframe before taking each picture.
You can use one, two, or group of points together depending on the scene and photograph you want to take.
To select a focus point, press the AF point selector button then scroll through the points with the camera to your eye, until the required point is illuminated in the viewfinder.
Professional photographers often prefer manual AF point selection over automatic.
It gives them total control on how and where to focus on the subject.
For example, you can achieve sharp and precise focus on a very small area of your subject with single point Autofocus.
Cross Type Focusing Points
One final piece of jargon to explain when it comes to autofocusing: cross type focusing points.
Most DSLRs offer a cross-type focusing point in the centre of the frame, but others offer further cross-type points at other focusing points.
They all perform the same function; focusing on image contrast both vertically and horizontally, which delivers a more accurate focusing result.
Naturally, the more cross-type focusing points your DSLR has, the better the system will work.
AUTOFOCUS POINTS SYSTEMS
It’s quite easy to compose a good shot with 51 point AF system than using a camera with only 9 focus points.
This is how both AF point systems looks like side by side.
I personally use a Canon 60D which only has 9 Focus Points.
For most of my photography, I use Evaluating metering mode and only the centre focus point activated.
To compose a shot, I first place my centre focus point on the subject I want the focus on and press the shutter release half-way down to lock focus.
I then move my camera to compose the shot and press the shutter button completely to capture it.
This is my usual workflow when working with a 9 point AF system camera.
When you have 51 focus points scattered through your viewfinder, covering all the major areas from left to right and top to bottom, you can straightaway compose your shot and move one or more focus points onto the area you want the focus on.
Hit the shutter button and it’s done.
Camera manufactures are now adding more and more focus points and Canon EOS R is a great example with a total of 5,655 manually selected AF points covering 100% of the frame from top to bottom and 88% horizontally.
Such high number of focus points allow you to establish focus on your desired spot with pinpoint accuracy.
DOES NUMBER OF AUTOFOCUS POINTS MATTER?
Autofocus systems are becoming far more sophisticated.
It has reduced the opportunity for the photographer to get focus wrong.
it’s really nice to have a sophisticated Autofocus system but not absolutely necessary.
Having a lot of autofocus points is particularly useful in taking action shots.
When there are a lot of focus points scattered through the viewfinder, It’s easier for the camera to keep the object you are tracking in focus.
So the bottom line is that more focus points are better.
Even the most basic DSLR now comes with 9 points AF system.
TYPES OF AUTOFOCUS MODES
There are three primary focus modes that give you a tremendous amount of flexibility to capture exactly what you want.
One Shot Focusing Mode
Straight out of the box, your DSLR is likely to be set on One Shot focusing with all focusing zones active.
In this case, the camera will automatically determine where the main subject is in the scene and lock focus onto this point.
With the focus locked, you can reframe the image by keeping light pressure on the shutter release, then pressing down fully to take the shot.
This option is fine for a large proportion of images where the subject is static.
Servo or Continuous Focusing Mode
If you’re focusing on a moving subject, you need to activate a focusing mode that constantly refocuses, right up to the point the image is taken.
This is typically known as Servo or Continuous focus mode.
In this mode, the camera will track the subject across the focusing points and, essentially, predict where the subject will be at the precise moment when the picture is taken, ensuring sharp focus.
Automatic Autofocus Mode
Many DSLRs also offer a focusing feature that provides the best of both worlds
The camera detects whether the subject is moving or static and selects Continuous or One Shot focusing accordingly.
Each manufacturer gives this dual-function autofocusing a different name.
Canon calls it AI Focus while Nikon named it AF-A, which stands for Automatic Autofocus.
Your camera also comes with metering modes to determine the correct exposure depending on the amount of light that goes into the camera.
Often, a DSLR’s metering system is linked to the active focusing point.
These metering modes works along with your camera’s Autofocus points as well.
The most common metering modes in DSLR’s today are:
- Spot Metering
- Centre Weighted Metering
- Evaluative Metering
The type of metering mode selected directly affects the overall exposure and mood of the taken image.
Let’s take a closer look at the above mentioned metering modes, how they work and when to use them.
Evaluates light around a selected focus point and ignores everything.
I personally use this mode a lot in my bird photography as they mostly occupy a small area on the frame.
Because the light is evaluated where I place my focus point, I could get an accurate exposure on the bird.
Centre Weighted Metering
This metering does not look at the selected focus points and only evaluates the light in middle of frame.
I use Centre Weighted Metering for close-up portraits and relatively large subjects that are in the middle of the frame.
Evaluative in Canon and Matrix Metering in Nikon is the default metering mode on most DSLR’s.
One of the key factors that affects this mode is where the camera focus point is set to.
It reads information from the entire frame and then prioritize the area around your selected focus point.
I use this mode for most of my photography since it does a pretty good job at deterring the correct exposure.
You can greatly improve the composition of your shots by selecting the right focus points and metering mode.
Composition in photography is not always about the perspective or the rule of thirds.
It’s a process, carried out carefully by combining creative and technical skills together.
A good eye in photography is all about selecting the right area to focus on, selected the right focus points and how to evaluate exposure around them.
But don’t forget about manual focusing.
Most DSLRs offer a switch on the lens or camera body which enables you to flick over to manual focus.
Why should you bother focusing manually?
Well, there will be times when autofocus won’t be able to cope, typically when faced with subjects that have little or no contrast, are in low light or are highly reflective.
When this happens, it’s time to go switch to manual and use the focusing ring on your lens to ensure you get sharp pictures.