KelvinCam: Light Meter

KelvinCam turns your iPhone into a precision light meter and color temperature reader for photographers, filmmakers, and lighting pros.

Measure exposure (EV), lux/foot-candles, and white balance in Kelvin instantly. Save readings, match your lighting, and nail every shot.

Everything happens live on your device. Your camera feed is processed live on your device and never stored, transmitted, or shared.

— WHAT IT MEASURES —

• Color Temperature — the large Kelvin number tells you how warm or cool your light is, with a gradient bar showing exactly where it falls on the warm-to-cool spectrum.

• Tint — the green-magenta axis that color temperature alone doesn't capture, critical for fluorescent and LED environments.

• EV100 — exposure value normalized to ISO 100, shown as a human-readable label (Candlelight, Indoor, Overcast, Full Sun, and more).

— PHOTO & VIDEO MODES —

Photo mode gives you full control with eight scene presets: Auto, Portrait, Landscape, Action, Golden Hour, Sunset, Indoor, and Low Light — each one biases the recommendations for that shooting situation.

Video mode applies the 180° shutter rule automatically. Select from preset frame rates (24, 25, 30, 50, 60, 120 fps) or type any custom value, and KelvinCam calculates the correct shutter for natural motion blur. It will also tell you when you need an ND filter and which strength.

— LOCK & SOLVE —

Tap Shutter or ISO in the recommendations card to lock it. KelvinCam solves for the other value in real time — like shooting in semi-automatic mode. Useful when your camera has a fixed frame rate, a maximum usable ISO, or a creative shutter speed you want to hold.

— LIVE HISTOGRAM —

Tap the waveform button to open a live luma histogram. Red and blue clipping indicators warn you when highlights are blowing out or shadows are being crushed, with percentage readouts showing exactly how much of the frame is affected.

— SNAPSHOT HISTORY —

Save any reading with a tap. Each snapshot captures the full picture: Kelvin, tint, EV, light source, mode, frame rate, scene preset, and all three recommended settings — timestamped and annotatable. Add notes to log a location or studio setup, then share as formatted text.

— CALIBRATION —

Align KelvinCam to a trusted reference meter using independent offsets for EV (±3 stops), color temperature (±500 K), and tint (±15). A live comparison card shows raw and calibrated readings side by side as you adjust.

— BUILT-IN GUIDES —

Seven in-depth guides cover the exposure triangle, shutter speed, ISO and noise, color temperature, the 180° shutter rule, reading EV, and a complete app walkthrough.

— FILM STOCKS (PRO) —

Shooting film? Choose your stock, from Portra and HP5+ to Tri-X and beyond, and KelvinCam pins ISO to the box speed and automatically corrects long exposures for reciprocity failure. Your night and low-light frames land at the right time, and each stock carries notes on its character and handling.

— CONTRAST RATIO METERING (PRO) —

Spot-meter your key light and mark it, then meter the fill. KelvinCam reads out the lighting ratio in stops, so you can dial in exactly the contrast you want, from flat and even to deep and dramatic.