Exposure & Metering

The exposure triangle

To double the light (one stop), open the aperture one stop, double the shutter time, or double the ISO — any one gives the same result. To halve it, do the reverse. You can raise one and lower another by the same amount to hold exposure constant while changing the look.

Sunny 16 no meter needed

On a clear sunny day at f/16, the shutter speed is the reciprocal of the ISO: ISO X → 1/X s. So ISO 100 → 1/100 s at f/16. Open up as light drops (f/11 hazy sun, f/8 overcast, f/5.6 heavy overcast).

Metering modes (Sony Alpha)

• Multi — balanced everyday metering across the frame.
• Center — weights the middle of the frame (Sony's on-screen name).
• Spot — reads a small area only; use for high-contrast subjects (but not pointed straight at a bright light source).
• Highlight — protects the brightest tones; good for skies.

Tricky scenes — where to meter

• Backlit sky — meter the sky from the side.
• Bright landscapes (beach, snow, sunny) — take the reading from the sky.
• Reflecting sky (coast, lake reflections) — meter from the reflection.
• Very green landscapes ("Green Jeans") — expose at −2/3 EV from what the meter suggests.
• Moonlit shots — meter the sky around the moon; e.g. f/11, adjust shutter to a correct reading (~1/8 s worked at that DR), tripod + 2 s timer.

Expose to the right, protect highlights

Set the rear LCD to a fixed manual brightness (Ian Taylor keeps his at zero) and a neutral picture profile with contrast and saturation reduced, so the screen matches your eye and you can judge exposure by it. If you push exposure right (ETTR), check the RGB histogram so no single colour channel clips — that dulls colour. For landscapes, expose for the highlights and lift the shadows in post; the a7R III recovers shadows very well.

Creative exposure — 7 starting points

Adapted from Bryan Peterson, Understanding Exposure:

Intent	Setting
Storytelling — deep DOF	f/16, f/22, f/32 (wide lens)
Singular / isolation	f/2.8, f/4, f/5.6 (telephoto)
Critical sharpness	f/8, f/11
Freeze action	1/250, 1/500, 1/1000
Panning	1/60, 1/30, 1/15
Imply motion	1/4, 1/2, 1 s and beyond

Other tools

Bracketing — shoot a range of exposures and blend or pick the best when the dynamic range is extreme. HDR feel — bring highlights down, shadows up, add contrast to tame shine.

Backlit and bright-sky scenes

• Spot on a mid-tone of the subject exposes the subject correctly — but a dark subject against sky will blow the background out. That "high key" result is a valid choice if you make it on purpose.
• Multi is more forgiving: it underexposes the subject but preserves the sky, and lifting shadows is far easier than recovering clipped highlights.
• Exposure Comp.: bright background → start +1 EV to +2 EV and raise until the sky is on the edge of clipping. Dark background → start −1 EV so rim light and highlights survive.
• Sunsets: Spot on a mid-tone away from the sun. Metering a dark area overexposes and washes the colour out; metering the sun itself blackens the scene.
• Snow, frost, white sand: add positive compensation — the meter drives a predominance of white towards grey.
• Bright sky over dark foreground: the general expose-to-the-right advice inverts. Protect the highlight and accept a dark foreground — see Bright Skies & Dynamic Range.

Consolidated from notes: Increasing exposure; Increasing/decreasing exposure using Aperture, shutter or ISO; SUNNY 16 RULE Exposure; Challenging exposure scenes; Creative Exposure Settings; Ian Taylor - exposure tips; For landscapes Expose for the highlights; Metering modes on Sony Alpha; Exposure bracketing; Reduce saturation and highlights