There really is more to autofocus than meets the eye.
In this episode, Gina and Valerie discuss how a camera focuses, the different kinds of autofocus, how to change focus points, single vs continuous focus, the problem with “focus and recompose” technique, and how to help your camera see better. Gina shares practical exercises to help you nail autofocus.
Keith Macke Senior portrait
How does a camera focus?
What are the different kinds of auto focus?
1. Manual Focusing Mode
2. One Shot Focusing Mode (Single)
One Shot / S-AF / Single Servo / AF-S / S
- easiest type of autofocus. press the shutter-release button halfway
- your camera may have a separate AF-ON button
- camera will lock focus on a subject on which you have placed the active autofocus sensor.
- Press the shutter button the rest of the way to take the image.
- Aim, focus and shoot.
- If you or your subject moves you may miss focus
- Static objects
- Still life
- Portraits that are static
3. Automatic Autofocus Mode
AI Focus AF (Canon)/AF-A (Nikon), which stands for Automatic Autofocus.
- New feature in entry level
- Most mid and pro bodies don’t have this feature
- Camera or Hans selects the mode for you AF-C and AF-S (Nikon)/One-Shot AF and AI Servo AF (Canon) depending on the situation.
- Camera switches between single and continuous focus
4. Continuous Focusing Mode
- AI Servo AF (Canon) Artificial intelligence continuous focus
AF-C (Nikon) Continuous Focus
Place focus point over the area of the moving subject
- Eye of a portrait where the person is moving
- Always choose the closest eye to camera
- Or car or bike or ferris wheel etc
- Camera’s computer will continually update the focus as the subject moves
- The trick is to keep the AF point on the part of the person or object you want to remain in focus
Types of focus points
- Allows you to focus with one single point or a group of points
- If you’re photographing a person you want single
- If you’re photographing a moving object or want a safety net you may want to go with a safety net of dynamic area AF
1. Go into Menu
2. Select AF Mode (Nikon AF-Area Mode)
Single point AF
One focus point that you can move around
Assigns a wider group of focus points so you end up with a larger area to focus with
Dynamic area AF
Single focus point with a few points either side just in case you miss
Auto Area AF
Camera finds the best place to focus
A face or skin tone
Generally locks onto the closest subject in the frame
- Many cameras today will shoot in continuous or single focus modes on whatever focus points mode you select
- I still prefer single AF point for all my shooting.
- You may like to experiment if you are shooting birds in flight, sport etc
How to change focus points
How many focus points do you need?
Not all focus points are created equal
- Cross points in phase detection analyse vertically and horizontally
- Basically lock on better
- Most entry level have cross point in the middle
- Mid and high end and some mirrorless have more cross points
- If shooting on entry level try midpoint to focus
The problem with focus and recompose technique
- If you or your subject more your shot will be soft
- Impossible on a tripod
- Very difficult to direct using this technique
- Frustrating for beginners
How to help your camera see better
Add contrast to low contrast images to avoid the dreaded “hunting for focus”
How to adjust your camera’s focus system
Camera tends to focus in front of the area you want on focus.
Camera tends to focus just beyond of the area you want on focus.