A Lumu alternative for iPhone

What Lumu did

Lumu was a small light sensor that plugged into the bottom of an iPhone, with an app that turned the phone into a handheld meter. The app alone is a reflected spot meter through the camera. With Lumu Power attached, its App Store listing describes incident exposure readings through the dome, flash, color temperature with green and magenta, chromaticity and lux. For a lot of photographers and filmmakers it was the first light meter they owned, because it lived on the phone.

What has changed

The Lumu Light Meter app on the US App Store was last updated on March 17, 2022, at version 3.3.6, and it asks for iOS 12 or later. Lumu Power plugs into a Lightning port, and every iPhone since the iPhone 15 has a USB-C port instead, so a Lightning accessory would need an adapter. We have not tested Lumu Power through one. We could not read whether Lumu Power 2 is still sold: lu.mu showed us only its title on November 2, 2026. See their site for the current state.

If yours still works on the phone you have, keep using it. If you are looking for what to use next, the answer depends on which part of Lumu you used.

What to use instead, job by job

What Lumu Power did, from the Lumu Light Meter listing on the US App Store. Prices from each seller's own page, checked November 2, 2026.

Color without an attachment

Cutvey Meter reads the color of light through the iPhone or iPad camera, with nothing plugged in. It starts on the camera's auto white balance, which reads the whole frame the way the camera does; tap the reading and it switches to a gray card, so you fill the frame with a card facing the light. Either way you get kelvin and tint, and a badge that says how steady the reading is: HIGH, MEDIUM or LOW, and DIFFICULT SOURCE when the light flickers, when the card is lit by two colors at once, or when the color is past what the camera can read.

From there it does what a color meter is for on set. Pin a light with REF, or type a target from 2,000 to 10,000 K, then point at the next light, and it names the CTO or CTB that closes the gap in LEE or Rosco numbers. It keeps the ND for your rig on screen, warns when the camera sees a light flicker, draws the sun's path over the live view and plans any place on a map. The Apple Watch app counts down to golden hour and logs a reading with a Double Tap.

It reads three color channels through a camera, so it is a different kind of reading from Lumu Power's sensor. It shows no spectrum, and its lux is worked out from the reflected exposure assuming an 18% gray surface.

One job: a portrait day that used to run on a Lumu

A morning of portraits in a studio with a big north window, then a short interview video after lunch. On the Lumu you metered the strobes with the dome and read the window's color before deciding whether to gel the modeling lights.

Split it now by job. Meter the strobes with a handheld flash meter: no phone camera can read a flash. For the window, open Cutvey Meter, fill the frame with a gray card in the window light and read the kelvin and tint; it changes through the morning, so log a reading at each setup and each one keeps the frame you were pointing at. For the interview, pin the window with REF and point at the LED key, and the card names the gel that matches the two. Set the rig for the video camera and the ND for the window-side wide stays on screen.

Where Cutvey Meter falls short of Lumu Power

It cannot take an incident reading or read a flash, and it shows no chromaticity figures. If those were what you used a Lumu for, a handheld meter is the honest replacement, and a Sekonic L-858D-U is the common choice. Cutvey Meter needs iOS 17 or later and runs on iPhone and iPad, with no Android version. Where it goes further than Lumu ever did is everything after the reading: gels in the book you carry, ND for your rig, flicker, the sun and the watch.