Understanding Focus in Photography
If you’re just starting out and have already encountered problems with blurry photos, then it’s likely that that a mis-focusing error is the cause.
For the most novice among you, I remind you that focusing in a photo is the action of to bring a subject or an image into focus as a whole.
When you start out in photography, you don’t always know where the blur you see in your images comes from, and that’s when the confusion between the different blurs arises.
Because, yes, blur can set up in different ways.
A missed focus in automatic mode is often due to a wrong choice of the collimator or autofocus mode.
We will see in this article what are the different ways to focus on your subject.
Manual focus and autofocus
There are two ways of focusing with your camera.
The first way is to focus manually.
First of all, select on your camera and on your lens, the M or MF (manual focus) symbol.
Then simply turn the focus ring on your lens to make the picture clear everywhere, using a small aperture or only part of it, if you have chosen a shallow depth of field (large aperture).
A green dot at the bottom of the viewfinder indicates that the focus is good.
The last way to get a subject in focus is to rely on autofocus.
The autofocus system focuses automatically without the need to rotate anything.
However, it is important to understand how autofocus works to avoid focusing errors.
The different collimators and their functions The collimators are represented by squares and rectangles with dots inside.
These are important for successful focusing.
Let’s see why.
They will be useful for photographing horizontal subjects.
Conversely, autofocus will have more difficulty focusing.
You’ll understand why afterwards.
Focusing will be easier when using horizontal collimators if the subject is oriented vertically.
The reverse can cause some problems.
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Or square, it’s the same thing, but you’ll understand why.
Take a vertical and a horizontal rectangle and you get a cross.
The merging of these two collimators
increases the chances of being able to take perfect focus according to the orientation of the subject.
The crosshairs are not physically represented in the viewfinder.
MAP is performed when one or more points are lit and fixed.
A green dot also indicates good focus at the bottom of the viewfinder.
To focus, cameras offer different areas for selecting collimators.
Auto AF area mode lets the camera use all the targets to focus.
Selective-point AF area mode lets you choose a single collimator to focus on.
Dynamic-area AF mode lets you use multiple targets for more precise focusing.
The AF area mode with 3D tracking allows you to use all collimators to focus.
It is a mode that detects color and light intensity to ensure optimal tracking of the subject with 3D tracking, especially when moving sideways.
It is particularly suitable for subjects with high contrast.
The AF-S system (Nikon) or AF-One shot (Canon)
This is the mode that is used especially for subjects that are motionless or barely moving.
Let’s see why.
You choose a focus frame with the shutter release button and press the shutter release button halfway down to focus on the desired location.
As long as you keep your finger on it, the MAP is memorized.
This means that at the time of shutter release, the camera will focus at the point where you have positioned the collimator(s).
However, care must be taken with subject or photographer movements, which can cause the camera to focus out of focus if the subject or photographer moves outside the sharpness range (wide aperture).
This is the preferred mode for everyday use, but it is not suitable for moving subjects.
The AF-C system (Nikon) or AF-Servo Ai (Canon)
This is the mode to use when you want to shoot moving subjects.
MAP is taken continuously on the subject while keeping your finger on the shutter release button, so the selected collimator(s) will follow the subject’s movements.
Extending your finger over the subject will take the picture with successful focusing.
This mode requires some experience at first, but it is very useful when taking pictures of birds, children, or sportsmen and women, for example.
AF-A (Nikon) and AI Focus (Canon) systems
In this mode, the autofocus system will choose to automatically switch between AF-One Shot and AF-Servo AI modes based on the subject’s movement.
Not all camera bodies have this feature.
At Nikon, it is exactly the same principle, the system will choose whether or not to switch from AF-S to AF-C mode depending on the subject’s movement.
This mode is available on some yellow branded SLR cameras.
Why the autofocus system slips
In some cases, the autofocus may not be able to focus, and this is due to a lack of contrast.
If you try to focus on the sky for example, the autofocus will be inoperative because there is no focus point.
On the other hand, if you focus on a plane, a contrast point is created, you understand?
This is also true in dark environments where focusing can be tedious.
The trick to assist autofocus is quite simple.
Simply point a light source at the subject to be photographed.
A flash mounted on the camera can be helpful in focusing by sending out its light beams.
The cropping technique
It is sometimes useful to want to off-centre a subject to avoid it being in the centre of our image.
The subject is often out of the frame, and the collimators are not able to position themselves in the desired location.
This is where the cropping technique comes into play.
In order to succeed in this technique, I advise you to select the central collimator because it is the most precise.
Lock the focus (hold it halfway) on the desired place, for example on the eyes (for a portrait), crop the image immediately and shoot.
You can use three modes with this technique.
- The AF-S autofocus mode (at Nikon) and One-Shot AF mode (at Canon), above.
- The AE-L / AF-L button
- The AF-ON button
Another method is to lock the focus, exposure, or both at the same time.
The AE-L /AF-L button can be set via the camera body menu to focus only.
In AF-S or AF-C, aim at a point on the subject, press halfway while pressing the AE-L or AF- L button, move the frame to recompose the image, and without releasing anything, extend your finger on the shutter release button to take the picture.
The last method is to use the AF-On button, which is also used to focus, but without having to press the shutter release button halfway.
This is a habit that can make your life easier.
You focus on the subject, press AF-On to focus, reframe, and release the shutter-release button all the way down.
Now, I hope you understand how it works, all you have to do is practice regularly and take beautiful pictures.
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