Compose

Calibrating the meter on the Compose screen (it disagrees with my camera)

A phone is not a light meter — every handset is off by half to a full stop. Calibrate once and it stays right.

① If the panel shows a yellow "reset to zero" prompt, tap that first — without resetting you will fold your other settings into what you think is the handset offset.

② Find a mid-tone surface that is neither bright nor dark (bare concrete is ideal), set the app and your camera to the same ISO and aperture, and meter it with both.

③ Compare the recommended shutter speeds: if the app is slower, drag the slider towards +; if it is faster, drag towards −. Keep going until both read the same — each step is 0.1 EV, so you can match exactly rather than settle for close.

No grey card — what can I meter off instead?

Dry bare concrete walls and pavement slabs work best — even in colour and not reflective.

Next best: well-worn denim, or the side of a dark grey camera bag.

Avoid white walls, snow, white paper and anything pure black: at those extremes the phone has already processed the image once, so what you measure is not the handset offset.

Calibration still will not line up? Check these first

The two metering modes differ (spot in the app, average on the camera) — you are not measuring the same patch at all.

ISO or aperture is not matched: however many stops apart they are, that is how far off you will be.

You are comparing against a finished shot from the camera — that frame already includes the compensation you dialled in, so it is not the camera’s raw reading.

You calibrated off one surface only. Meter two or three places of differing brightness and take the value they agree on.