Metering and focus modes

The default metering and focus settings are right maybe eight times out of ten. The other two, a backlit face, a snowfield, a toddler who won't stop moving, are where frames get lost. You don't need every mode memorised, just when each one earns its place.

1. What each metering mode measures

Every meter does one job: it exposes whatever it reads as middle grey. The modes only change how big that patch is.

Some bodies add highlight-weighted or partial metering under various names. Same idea, a different area or weighting. Check the manual to see what yours has.

2. Metering still needs compensation

Since the target is middle grey, snow comes out grey, and so does coal. The camera has no idea what colour the thing was. The old rule fixes it:

Add for white, subtract for black. If the scene is mostly bright, dial in plus compensation; if it's mostly dark, dial in minus.

• For snow, white walls and bright skies, start around +0.7 to +1.7 stops.
• For night scenes, black clothing and low-key still life, go −0.3 to −1 stop.
• Then check the histogram. The screen lies about brightness; the histogram doesn't.

3. AF-S, AF-C and focus areas

Focus has two layers of settings, and most people only ever touch one.

1. Focus mode decides whether the camera keeps tracking after it locks. AF-S (single) locks and holds: still life, landscape, posed groups. AF-C (continuous) keeps adjusting: kids, pets, sport. Canon calls them One Shot and AI Servo.
2. Focus area decides where it looks. A single point is the most precise and asks the most of you; zone and expanded point sit in the middle; wide or auto leaves the call to the camera, which is fine with a clean background and loves grabbing the railing in front when the scene is busy.

Worth trying: back-button focus. Move focus off the half-press onto a thumb button and the shutter only fires. In AF-C, lifting your thumb holds focus, as if you'd switched to AF-S.

4. Where eye AF stops working

Eye AF is very good now, but it still fails in predictable ways.

• In dim light there isn't enough contrast to detect anything, and the camera falls back to ordinary AF.
• With a profile, a bowed head or a turned back, there's no eye in frame and the box wanders off.
• Sunglasses, masks, railings and foreground branches all break it.
• If the person is a speck in the frame, not finding an eye is normal.
• In a group it may lock onto someone in the back row. Switch to a single point and put it where you want; that's quicker than half-pressing over and over.

5. Setting up for remote shooting

Shooting from a phone puts a wireless link between you and the shutter. Live view usually lags 0.2–0.5 seconds and commands take a moment too, so set the camera up differently.

1. Use AF-S with a single point. For a remote self-portrait, focus where you'll stand, or go manual focus and leave it. You can't chase focus through a lag.
2. Lock exposure in manual. One passing cloud changes the brightness of every frame. For group shots, time-lapse and astro, fix aperture, shutter, ISO and white balance.
3. Meter once in evaluative, copy the reading into manual, then leave it alone.
4. Judge on the histogram, not the phone screen. A phone display fools you the same way the rear screen does.

Zlens is being built to put live view, settings and transfers in one app, so you aren't hopping between each maker's own app. It is not released yet. Which bodies and which settings it reaches will be listed on its own site, and any remote app can only control what the camera's protocol exposes.

6. FAQ