Cutvey Meter vs. the Sekonic C-800

What each one costs

	Price as printed	What it is
Sekonic C-800-U SpectroMaster	$1,899.00	Handheld spectrometer: spectrum, color rendering, flash, gels
Sekonic L-858D-U SpeedMaster	$689.00	Handheld incident and flash meter with a 1° spot. No color
Sekonic C-4000	$1,199.00, shown out of stock	Spectrometer run from an app over Bluetooth
Cutvey Meter	Free to download. Unlock Forever, $19.99, once, or included in a Cutvey plan for each person on it.	Color meter and sun tracker for iPhone, iPad and Apple Watch, through the camera

Hardware prices from sekonic.com's US store, checked November 2, 2026; the C-4000 page showed "Out of Stock" that day. Cutvey Meter's price is the US App Store's.

What a spectrometer measures

The C-800-U has its own sensor, built to read light and nothing else, and it splits the light into its spectrum from 380 to 780 nanometers. From that one measurement it works out the color temperature anywhere from 1,600 to 40,000 K, the illuminance, and the figures that say how well a light renders color: CRI, SSI, TLCI, TLMF and TM-30-18. It reads flash. It names the LEE or Rosco filter that corrects a light, and the camera filter that corrects a lens, and it can compare several lights at once.

That spectrum is the part no phone can copy. Two LED panels can both read 5600 K and look different on skin, because one of them is missing part of the spectrum. A spectrometer sees the gap. It is the instrument you want when you are buying or approving fixtures, matching RGB LEDs by spectrum, or when a reading has to stand up as a measurement.

What a phone reads

Cutvey Meter reads the light the way the camera sees it. The iPhone's camera works out the color of the light from what lands on its sensor, through red, green and blue filters, as it sets its own white balance. The app turns that estimate into kelvin and tint through the lens's own color model, from the whole frame or from a gray card that fills it, and it takes a median over many samples so one stray frame does not move the number.

That is a real reading of the light in front of you, and it is what you need to set a white balance or pick a gel. It is also an estimate, so the app says how far to trust each one: HIGH, MEDIUM or LOW, and DIFFICULT SOURCE when the light flickers, when a card is lit by two colors or when the color is past the camera's range. A steady light with a spiky spectrum can still read HIGH and be off, because three color channels cannot see the shape of a spectrum. On a light like that, test a gray card on the camera itself.

Side by side

Job	Sekonic C-800-U	Cutvey Meter
What it measures with	Its own sensor, across the spectrum from 380 to 780 nm	The phone camera's white balance, in three color channels
Color temperature	1,600 to 40,000 K	Kelvin and tint, live; no figure for a light far off the black-body line
Color rendering	CRI, SSI, TLCI, TLMF and TM-30-18	No
Tell two LEDs apart at the same kelvin	Yes, by their spectra	No; it cannot see a spectrum
Light level	Illuminance from 1 to 200,000 lux	Lux worked out from the reflected exposure, assuming an 18% gray surface
Flash	Yes	No
Gel answers	LEE and Rosco lighting filters, and camera filter answers	CTO or CTB in LEE or Rosco numbers, at most two sheets
Matching lights	A multiple-light mode	REF or a typed target, MATCH within 5 mired
ND for your rig	No	Yes, live, or it solves ISO, stop or shutter
Flicker	Not on its product page	Warns when the camera sees banding, with a flicker-safe shutter
The sun	No	Path over the live view, golden and blue hour, a map with shadows
Where readings go	A utility for a PC or Mac	Kept on the device with the frame you pointed at
On your wrist	No	Apple Watch app

The C-800-U from sekonic.com's product page, read November 2, 2026.

One job, both tools: a commercial lit with rented LEDs

Prep day at the rental house. The gaffer has a C-800 on the cart and twelve LED panels on the floor. This is the spectrometer's job: read each panel, check its color rendering, find the two that do not match the rest even though they all claim 5600 K, and note which gel or setting brings the odd ones in. A phone cannot do this part.

Three days later you are on the scout without the cart. The phone is in your pocket. Read the window light in the living room at the hour you will shoot it, pin it with REF, and see how far the practicals in the hallway sit from it and what gel closes the gap. Open the sun screen to see where the sun will be at four o'clock, and drop a pin on the map to see the shadow of the building across the street. Log each reading, and each one keeps the frame you were pointing at.

On the day the C-800 stays with the gaffer. Between setups, when somebody asks whether the new practical is close enough, the phone gives a quick answer with a badge that says how much to lean on it, and the wrist counts down to golden hour.

When to choose the C-800

You need color rendering figures: CRI, TLCI, SSI or TM-30.
You are buying, approving or matching fixtures, especially RGB LEDs.
You meter flash.
A reading has to be a measurement you can defend, more than a starting point.

If what you need is incident exposure and flash without color, Sekonic's L-858D-U is $689.00.

Where Cutvey Meter falls short

Against a spectrometer, a long way, and plainly. It shows no spectrum and no color rendering figure. It cannot tell two lights of the same kelvin apart by their spectra. Its lux is a reflected estimate, so it is no incident meter, and it does not read flash. We publish no accuracy figure for it against a C-800 or any other meter, because none has been recorded. It is the second opinion that is with you when the instrument is in the truck, and it says so on every reading.

If you own both

Keep the C-800 as the reference. Cutvey Meter lets you set a calibration offset for each lens, in kelvin and tint. It is one constant shift per lens, so it cannot follow an error that changes from warm light to cool; check it at the temperatures you shoot. Logged readings are stored uncorrected, with the offset noted beside them, so nothing is lost if you change it later.