We benchtest the first app to turn your iPhone into a professional light meter. It looks good, but has one slight flaw…

With the growing number of people interested in all things lighting, wouldn’t it be great to have access to a high-quality light meter to perform some instant light measurements?

In an instant, your could close that deal by showing clients how bad their lighting really is, quickly compare the output of one piece of lighting kit with another and expose fraudsters with their poor quality lux diagrams.


Although lux meters don’t cost the earth (we swear by our office Iso-Tech 1337, £84 from RS Components), they can be bulky to carry around for occasional use. Now, for just 59p, iPhone 4 users can be instantly equipped with a light meter thanks to the LuxMeter Pro app from AM PowerSoftware.

So can we really consign our light meters to the nearest WEEE recycling skip?

You need to calibrate the LuxMeter Pro before you can use it

You need to calibrate the LuxMeter Pro before you can use it

First things first, the user interface is great. It has all the features you’d expect on a professional light meter: min, max and hold features. Readings are displayed in the traditional seven-segment digital format with a bargraph display.

Now for the downside. The iPhone 4 has two cameras: one on the display side, and one on the back with the LED flash. This app uses the camera on the back of the phone to measure the light, meaning when you put the iPhone down on a table to measure lux on a work surface, the sensor is covered up. The only way around this is to do a sort of limbo dance around the room, so the sensor points up, while you try to read the display.

Calibrating required

This makes more sense if the app is aimed at photography applications – but it isn’t. It’s branded to appeal to lighting engineers and designers. Which makes us suspicious that this is a repurposed piece of software.

The blurb says it all: the LuxMeter Pro a lux meter to measure light intensity. In fact, you’re required to calibrate the iPhone’s sensor before you can take a reading. So you need to already have access to a light meter, which kind of defeats the point if you trying to get away without buying a light meter by getting this app.You could use a surface with a known illuminance of course – if you can find one. We tested version 0.5. The next, version 1.1 has a fixed ‘zero’ camera gain value on start-up and improved camera calibration.

This piece of software has a great user interface, which would rival the best lux meters in the business, but in reality it’s about as much use as a holiday home in Tripoli.

If you want to waste 59p, then try it.

PHONE: iPhone 4 only
FUNCTIONS: Min, max and hold
COST: 59p
One star – mainly for its groovy graphics – is all this product is worth. The concept is a great one – how cool would it be to always have a lux meter in your pocket? – but the execution is terrible. And the fact you have to calibrate is a major pain. Use your 59p to get yourself a crisp sandwich from Asda instead.


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