Canon DSLR Tips 29-35
29 AE Lock
A disadvantage of Focus Lock is that by default it locks exposure as well as focus. This can lead to inaccurate exposures. You can avoid this by using the Exposure Lock button at the back of your camera (marked with a star). Use the Focus Lock, as above, then when the shot is recomposed, use the Exposure Lock button to reset the exposure before firing.
For more on this, check out our step-by-step tutorial on how to use AE Lock to control exposure.
30 Use Automatic Depth of Field (A-DEP)
A-DEP mode is the easy way to maximise depth of field, so all key areas in the image stay sharp. It works using the seven or nine AF points found on consumer SLRs, so the lens must be switched to AF.
Point the lens and the camera adjusts both the aperture and the focus to maximise depth of field (as well as setting the shutter speed).
31 A-DEP tips
A-DEP can only make use of those AF points it can get a reading on straight away. Check which it is using. Keep half-pressing the trigger until it uses all the focus points that you require.
32 Try manual focus
AF is useful, but in low light (or with some action subjects) it's more accurate to focus manually. Switch the lens from AF to MF, then turn the focus ring on the lens until the subject looks sharp in the viewfinder (for more on focusing manually, check out our in-depth guide to Manual Focus: what you need to know to get sharp images).
33 Love Live View
Checking the accuracy of manual focusing is not as easy as it sounds. Use Live View for more accurate results. The zoom option in Live View gives a 10x magnification and a panning option, so you can then focus precisely on any point in the frame.
34 Zoom effect
If you don't have Live View, zoom in with the lens and focus, then zoom out to reframe the shot and press the shutter to capture it.
35 Focus check
You can also use the LCD screen to check the focus on shots you've taken. Press the magnifying glass button several times to zoom into your shots, then use the cursor controls to check different areas.
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