Back in the day before autofocus was invented photographers had to rely on focusing by using the focus ring on the lens. The cameras back then had a ‘focusing screen’ built into them and most were a ‘split screen’ and you would turn the focus ring until you lined up the two halves of the screen. Simple enough but thanks to some crafty engineers our cameras are all autofocus now.
However, what most people do not realize is that there are several other factors that come into play regarding your camera’s autofocus system, namely focus ‘modes’ and focus ‘areas’. Hopefully this makes things a little clearer…no pun intended.
Focus Modes: This is the WAY that your camera focuses.
The camera manufacturers all have some variation as to how they refer to their focusing modes but if you aren’t sure you can always look up ‘focus modes’ in your instruction book.
AF-S, Single Shot AF: Press the shutter halfway down and the focus locks. This is good for stationary subjects.
AF-C, Continuous AF , AI Servo: Press the shutter hallway down, lock focus and keep the shutter pressed halfway-now if your subjects moves and you move with it the camera will refocus on the subject. This ’track focus’ mode is best for moving subjects.
Manual: Modern cameras do give you the ability to manually focus the lens. Switching the cameras focus mode to MF will disengage the AF system. Manual focus comes in handy when the light is too low, or the subject is very small in the viewfinder or you are trying to focus through glass.
Focus Areas: This is WHERE your camera focuses.
Again the manufacturers vary in their nomenclature and technology regarding auto focus ‘areas’ so consult your manual if you aren’t sure.
Auto Area AF: This is the default setting on all digital cameras. The camera uses all of it’s ability to try and figure out what the subject is, many times it chooses the closest subject.
Single Point AF: Switching to ‘single point focus’ will allow you to move a single point of focus around the frame of the camera.
Dynamic or Group Area: Similar to single point in that you are choosing a single point of focus but becuase it is in a group of points’ the camera will try to keep tracking the subject within the group of points. This is a MUST for sports, action or wildlife photography.
3D Tracking: Not offered by all cameras but this will automatically shift the focus based on the movement and speed of the subject. Great for unpredictable moving subjects, sports, butterflies.
More Focusing Tips:
*All lenses have a minimum focusing distance from their subjects. So if you find that you are trying to take a photo and the shutter will not release try stepping back a bit-you may be too close.
*Lenses need light and contrast to focus. If the light is too low the camera may not be able to focus, many cameras have an AF assist illumination in their menus (again check your manual)
If there is not enough contrast try moving your focus point to something in the frame that has contrast.
*Even if you are shooting in a ‘manual’ exposure mode you can still use the autofocus system.
*Manual focus on a case by case basis.
*Autofocus is better than you.