How to Focus

What will you learn in this guide?

• What makes a picture sharp
• What are focus modes
• Autofocus AF-S / One Shot
• Continuous AF-C / AI Servo
• Hybrid Autofocus AF-A / AI Focus
• Which focus mode should I use?
• Why your camera won’t focus

When a photo is in focus it is judged by our eyes based on the clarity on a subject’s outline. Basically how defined that object is against another. Sure, in most photos you’ll be able to see the shape of a subject clearly enough but making it pin-sharp will increase the drama, aesthetics and connection with an audience.

Your camera’s way of knowing how to focus is based on colour values. Pitting 2 well-defined areas of different colours against each other makes it easy for your camera to get the shot sharp. If you’re working with lots of tints and shades of the same colour it can be a lot harder. 

Give your camera an easy life and try to use opposing, or obviously different colours in your foreground and background.

Firstly, autofocus locks focus based on the distance to your subject. As long as your subject stays at that distance, your photo will be sharp. In some instances, your camera may not take the photo if your subject is moving.

But the benefit is that autofocus allows you to recompose whilst retaining focus. Imagine that you focus in the middle of a frame, but your main subject looks better further to the left or right.

To know how to focus in AF mode, all you need to do is keep your shutter button half-pressed to firstly lock focus on your subject and then (whilst still half-pressing the shutter button) shift your composition to suit. As long as you don’t change the distance between camera and subject then your shot should still be sharp.

Secondly is a continuous focus mode which places multiple autofocus ‘points’ on your subject and continues to adjust these points while your subject moves. You need to keep the shutter button half-pressed and your subject framed as they move for the focus to track correctly.

This is ideal for capturing movement in your shots. Athletes or just leisurely cyclists all benefit from AF-C. So on how to focus with movement, it’s best that once you’ve spotted your subject, track them by half-pressing on the shutter button and move the camera to keep them in the frame. 

When you are ready to take the photo, fully press the shutter down, and the camera will focus on your subject for a sharp photograph.

But if you let the camera decide how to focus and when, this method merges the functionality of the autofocus and continuous. Basically it begins as autofocus but your camera needs to lock in focus on a stationary subject first. Only then can you can take the photo as you would in a traditional autofocus mode.

But – and here’s the magic – if your subject starts moving, the autofocus stops and the continuous method takes over to track your moving subject. It gives you the best of both worlds.

Warning – Be aware though, if you recompose a stationary object quickly in AF-S mode, the camera may think the subject is moving and release the AF-S too soon. Try to keep the camera still until you’ve got your subject in the frame.

If you are too near the subject, then your camera may not be able to focus. Every lens has a minimum focus distance that you need to maintain.

Camera shake can account for areas of blur that occur during your exposure, even if your subject isn’t moving. Make sure your shutter speed is faster than the equivalent of your focal length (the reciprocal rule – important for long focal length lenses). For instance, shooting at 100mm, your shutter speed should be 1/100th or faster to avoid camera shake. 

Shooting handheld at 1/125th or slower is asking for blur to creep into your shot. Don’t chance it, get a tripod if you need to drop down slower or hike your ISO in worse case scenarios to keep the shutter speed suitable.