EOS mirrorless cameras have better autofocus (AF) coverage than the viewfinder AF on EOS DSLR cameras: they cover almost the entire image area and provide many more selectable AF positions. How does this change the way you operate the AF? Read on to find out! (Reported by: Takashi Karaki, Digital Camera Magazine)

 

Wider, denser AF coverage during viewfinder shooting

When you shoot still images through the electronic viewfinder (EVF) on a Canon EOS mirrorless camera, the autofocus (AF) system that is active is the image sensor-based Dual Pixel CMOS AF system, where each pixel on the image sensor can perform phase detection in addition to capturing light for imaging. This helps to achieve an AF area that covers almost the entire image area, as well as more possible AF positions (for example, the EOS R5 has up to 5,490 selectable positions).

This is compared to the viewfinder AF system on a DSLR camera, where the AF points are fixed in number and tend to be concentrated in the centre of the image.

For more details about the differences, see:
EOS R Specs and What They Really Mean

 

The actual AF coverage depends on your camera model and lens. On the EOS R system, this can be as much as approximately 100% vertically and 88-100% (depending on camera model) horizontally with compatible lenses.

How does this apply in the field? Consider the following image of the sky at sunset:

In this shot, the main interest is the sun at the bottom edge of the image, and that is where you want to place the focus.

Focusing with a DSLR camera

On a DSLR camera, simply composing and then focusing won’t work for subjects on the edges on the frame. You need to use the AF lock (‘focus and recompose’) technique:

Step 1: Acquire focus using one of the AF points.
Step 2: “Lock focus” by keeping the shutter button half-pressed.
Step 3: Recompose as desired.
Step 4: Take the shot.

Focusing with a mirrorless camera

On a mirrorless camera, as the AF area occupies almost the entire image frame, you can compose the shot almost any way you want from the start, without having to lock focus and recompose. This simplified workflow not only lets you shoot more quickly and efficiently, it also allows more creative freedom.

 

Bonus techniques: Using the different AF methods

Most of the time, Face Detection + Subject Tracking Priority AF (fully automatic AF) mode will be sufficient. However, in some situations, depending on the size of the subject, how it moves, as well as the degree of precision you need, using a different AF method might help you establish focus more easily.

Depending on your camera, you might have as many as up to eight AF methods to choose from. Here are two popular ones.

 

1-point AF: For pinpoint precision

‘1-point AF’ focuses using just one small AF point, which makes it ideal when the scene contains fine details or if the subject is tiny. It is a good choice for scenes where you have a main subject that doesn’t move much and takes up only a small part of the image frame. Some cameras also have a variation, ‘Spot AF’, which lets you focus on an area that is even smaller than 1-point AF.

Try this: Combine this mode with the magnify function and Touch AF for best results!

Examples of 1-point AF/Spot AF in use:
RF85mm f/2 Macro IS STM: A Closer Look at Nature
Flower Photography: Useful Techniques and Camera Features

 

Zone AF: For tracking moving subjects

Similar to its DSLR counterpart, the Zone AF mode divides the entire AF area into different zones, and conducts subject detection only within the zone that you have selected. It is good for subjects that move.

Know this: The Large Zone AF modes available on some cameras works in a similar way, except with larger zones. To decide on which to use, consider the size of your subject and the scope of its movement.

More examples of Zone AF and Large Zone AF in use here:
Sights of Switzerland: 5 Ways to Make the Most of the EOS R
Birds in Flight: Camera Settings to Increase Your Successful Shots

 

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