A Sekonic C-700R-U SpectroMaster Colour Meter costs around $1,500. A calibrated light meter app for iPhone costs $3. The hardware is more accurate. The phone is in your pocket. So which one should you actually use?
Short answer
| You are… | Use |
|---|---|
| A photographer, videographer or content creator | A phone app (e.g. KEV) |
| A gaffer, DP or 1st AC on a feature | Both - phone for fast checks, Sekonic for hero shots |
| A studio shooting catalog / e-commerce | A grey-card workflow + a meter |
| Shooting film | Sekonic for exposure, phone for colour temp |
| Anyone who’s never owned a meter | Start with a phone app |
What each one is good at
Phone-based light meter app
A modern phone camera + AI can read colour temperature surprisingly well. Apps like KEV - White Balance Meter AI use the iPhone’s rear camera, analyse the live preview, and output Kelvin + magenta/green tint in real time.
Strengths
- Always in your pocket.
- One-time purchase (KEV is $2.99) - no subscriptions.
- Reads tint, not just Kelvin.
- Updates live as you move - good for chasing magic hour.
- Calibrated against a Sekonic (in KEV’s case, the C-700R-U).
- Works on iPad and Apple Watch too.
Weaknesses
- Accuracy depends on your iPhone model.
- It uses the camera sensor, not a calibrated spectrometer.
- No incident-light dome - it’s a reflected reading by nature.
- Battery on your phone, not on a dedicated device.
Hardware meter (Sekonic, Kenko, etc.)
A pro spectrometer is a measurement instrument. It has a calibrated optical sensor under a diffusion dome, filters for spectrum sampling, and ships with a calibration certificate.
Strengths
- Lab-grade accuracy (typically ±50K).
- Reads CRI, TLCI, R9 and full SPD spectrum.
- Doesn’t drift across phone models or OS updates.
- Trusted on union sets.
Weaknesses
- $1,000 - $2,500.
- Another bag in the kit.
- Battery to charge, firmware to update.
- Overkill for 95% of working photographers.
When the app is enough
For most situations, an iPhone-based meter is genuinely enough:
- Wedding, event and lifestyle photography
- YouTube and short-form video
- Indie filmmaking and music videos
- Real-estate, interiors, product
- Content creation, podcast video, interviews
- Setting white balance for tonight’s vlog
In all of those, you need a number you can dial into the camera. KEV gives you one accurate to within a few hundred Kelvin, which is well inside the difference your eye can perceive in the final image.
When the Sekonic still wins
- Studio strobes and HMI flicker testing. Hardware meters can sample shutter-speed-relevant exposure timing; a camera-based app can’t.
- Spectral data (CRI, R9, TLCI). If you’re vetting lights for purchase or set, the SPD chart on a SpectroMaster is irreplaceable.
- Union features and broadcast. Some production environments require certified meters.
- Incident light exposure on film stock. Reciprocity and dome metering matter more.
How to think about the trade-off
If your work hangs on white balance being exactly right - say, a $30K product shoot or a feature film day - the Sekonic earns its keep. For everyone else, the iPhone in your pocket is the meter you’ll actually use, and the meter you’ll actually use beats the one sitting at home.
The hybrid workflow
The realistic answer is both.
- Carry KEV on your phone all day.
- Use it for every shot.
- Keep a hardware Sekonic in the bag for the moments where ±50K matters: hero shots, multi-cam sync, gel selection, product, VFX plates.
You’ll meter 100x more often, your colour will land 95% more consistent, and you’ll only crack the Sekonic open when you really need it.