How it works

1. Grant camera access — the app uses the camera to preview the scene and measure light.

2. Point at the subject — readouts update from the device’s metering.

3. Tap the preview to meter at a point; a short focus reticle shows where you tapped.

4. Use Auto mode to follow the meter, or Manual to open pickers for aperture, shutter, and ISO stops; the app shows EV vs the scene in manual.

5. Use histogram and/or waveform to see brightness distribution (whole frame vs where in the frame).

6. Lock to freeze numbers (and histogram/waveform snapshots) to note or share.

7. Settings (gear): app info, version, company, website, email, and rate on the App Store when configured.

Monetisation: 7-day trial (device-tracked) and a one-time non-consumable unlock; Restore purchases on the paywall.

General features

Camera toggle

• Switches which camera feeds the live preview and light meter—usually rear vs front.

• Readouts update to match the active camera.

Lock exposure

• Freezes current meter readings so they no longer follow the live scene.

• Use to note aperture, shutter, ISO, EV, white balance, and histogram, or to show values to other photographers so everyone can match exposure.

Aa (large type)

• Larger type for readouts and labels.

• Easier in bright sunlight, without changing system text size.

App features (metering readouts)

Aperture

• Shows f-stop the app reads for the scene.

• Lower f-number (e.g. f/2.8): more light, shallower DOF. Higher (e.g. f/11): less light, more DOF.

• Match to your lens for brightness and how much is sharp.

Shutter speed

• How long the exposure lasts.

• Faster (e.g. 1/500 s): freezes motion. Slower (e.g. 1/30 s): more light, more motion blur or shake.

• Balance sharpness, motion blur, and exposure.

ISO

• Sensor sensitivity. Lower: usually cleaner. Higher: brighter in low light, more noise.

• Use after aperture and shutter to reach a good exposure.

AWB with Kelvin

• Estimated white balance as Kelvin (K): warm (lower K) vs cool (higher K).

• Guide to match or tune camera WB for natural or creative color.

EV

• In manual mode, exposure compensation in EV (stops) vs the meter: how much brighter or darker than the measured scene.

• Positive: brighten; negative: darken for deliberate over or under exposure.

Histogram

Live graph: brightness spread across the preview (dark left, bright right). Three zones:

• Shadows: Left, darker tones. More curve → more in shadow; stacked far left → crushed blacks.

• Midtones: Middle; mid-brightness detail; most everyday subjects when balanced.

• Highlights: Right; bright tones and speculars; stacked far right → clip (overexposed).

In app: Toggle histogram from the top bar. Clipping pills (shadows / highlights / none) use histogram data.

Luminance Waveform

Turn on: Top-right icon (next to histogram toggle).

Behavior:

• Left–right = scene left–right.

• Bottom–top = brightness (shadows low, highlights high).

• S / M / H = shadows, midtones, highlights (lower / middle / upper thirds).

• “Safe exposure” legend + green line = reference band for a typical “safe” target—judge by eye for final look.

• Each column = density “cloud” at each brightness level—not one line per column.

Reading it

• Wide vertical spread in a column → that strip of the frame spans shadow through highlights.

• Stack high → strong highlights; low → mostly dark.

Green guide line

• Matches Safe exposure hint; mid-to-high luma reference for key brightness; refine by eye.

With the histogram

• Histogram: whole frame brightness sum. Waveform: where in the frame. Together: exposure + composition.

Technical (optional FAQ): Rec. 709 luma: Y = 0.2126R + 0.7152G + 0.0722B, normalised.