● Compare · KelvinCam · Light Meter LM-3000

KelvinCam vs Light Meter LM-3000.

KelvinCam and Light Meter LM-3000 are both light meter apps for iPhone, but they measure different things in different ways. LM-3000 is an incident light meter: you point the front camera at the light through a diffuser to measure lux and color temperature. KelvinCam is a camera meter. It reads the scene through the back camera and turns it into white balance, exposure and camera settings for photo, video and film.

We make KelvinCam. Facts about LM-3000 come from its US App Store listing, checked October 21, 2026.

§ 01 · The short answer Different tools

Which one fits your work?

Choose LM-3000 if

You need to measure the light itself.

How much light falls on a desk, a wall or a subject, and what color a lamp really is. Think lighting design, checking a building's lights or comparing bulbs. Its listing says it follows the ISO/CIE 19476 standard and comes calibrated for each device model. Its listing also says it was developed by optics scientists at the Zurich University of Applied Sciences. It needs a diffuser, which can be a sheet of printer paper.

Choose KelvinCam if

You're about to shoot and want the settings.

It gives you white balance in Kelvin and tint, exposure value, and the shutter, aperture and ISO to use. It reads them from the scene your camera will see. There are also tools for video (the 180° shutter rule and ND filters), film (reciprocity correction) and lighting ratios. No diffuser: you point the back camera at the scene, as you would your camera. See what KelvinCam does.

§ 02 · How they measure Incident and reflected light

Two ways to read light.

LM-3000

Incident light, front camera

You hold the phone where the subject is, with a diffuser over the front camera, facing the light. It measures the light arriving at that spot, the way a handheld incident meter does, using RAW image processing. That's the right method when the number you need is illuminance in lux.

KelvinCam

Reflected light, back camera

You point the back camera at the scene, averaged across the frame (or at one spot, with Pro). It reads exposure the way your camera's meter does, and color temperature and tint from the camera's own white balance. Lux is worked out from the exposure reading, so treat it as an estimate. Like any camera's auto white balance, it can be pulled by a scene full of one color. When it matters, meter something neutral, such as a grey card.

§ 03 · Side by side US prices

Feature by feature.

LM-3000 facts from its US App Store listing, checked October 21, 2026. Prices and features can change.
Feature	KelvinCam	Light Meter LM-3000
What it measures	Color temperature (Kelvin), tint, exposure (EV at ISO 100), and illuminance in lux or foot-candles, estimated from exposure.	Illuminance in lux or foot-candles, and correlated color temperature (Kelvin).
How it measures	Back camera, reflected light from the scene, averaged (spot metering with Pro).	Front camera, incident light through a diffuser, RAW processing.
Accessory	None.	Diffuser required: printer paper, or the maker's diffuser accessory.
Accuracy and calibration	Uses the camera's exposure and white balance readings. Pro calibrates to a reference meter: EV ±3 stops, Kelvin ±500 K, tint ±15.	Follows ISO/CIE 19476, calibrated per device model, with custom calibration to another meter.
Camera settings	Shutter, aperture and ISO, lock and solve, eight scene presets; equivalent exposures in Pro.	Not listed.
Video	180° shutter rule at any frame rate, ND filter suggestions.	Not listed.
Film	Film stocks with reciprocity correction (Pro).	Not listed.
Lighting ratio	Key and fill contrast ratio in stops (Pro).	Not listed.
Other tools	Live histogram, saved readings, freeze, seven guides, Home Screen widget.	Peak reading, HOLD with a sound, in-app manual.
Free use	Free version with no time limit; every Pro tool free for 20 minutes, once.	Free trial of two non-consecutive days.
Paid options	KelvinCam Pro, $9.99 once.	$0.99 for another 48 hours, $3.49 monthly subscription, or $19.99 once for unlimited use.
Devices	iPhone and iPad, iOS 18 or later.	iPhone and iPad, iOS 15 or later.
Languages	English.	English and seven more.
On the App Store	Since May 2026.	Since March 2021, with about 2,600 ratings in the US store averaging 4.5.
Privacy label	Data not linked to you, used for analytics.	Crash data, not linked to you, used for analytics.

§ 04 · Using both On a shoot

They work together.

On a lit set, you might use an incident meter such as LM-3000 to check how bright each light is where the subject stands. Then use KelvinCam to set white balance, check the key-to-fill ratio and get exposure settings from the scene the camera sees.

§ 05 · About this comparison Corrections welcome

Rivot Labs makes KelvinCam, so we aren't neutral. Light Meter LM-3000 is made by Lightray Innovation GmbH, which has no connection to us. Everything we say about LM-3000 comes from its US App Store listing as of October 21, 2026. "Not listed" means its listing doesn't mention the feature. If something here is wrong or out of date, email support@rivotlabs.com and we'll fix it.

§ 06 · Sources Checked October 21, 2026

Light Meter LM-3000 on the App Store (US). Its features, trial, in-app purchase prices, ratings and privacy label, as used in this comparison.
Light Meter LM-3000, by Lightray Innovation. The maker's own page about the app.
ISO/CIE 19476:2014, Characterization of the performance of illuminance meters and luminance meters (CIE). The standard LM-3000's listing says it follows.
temperatureAndTintValues(for:) and deviceWhiteBalanceGains (Apple Developer Documentation). The camera white balance readings that KelvinCam turns into Kelvin and tint.

§ 07 · Read next KelvinCam