Reviews |Lumu Power review

Lumu Power review

Lumu Power review

The Lumu Power is a light and colour meter with a Lightning connector. That connector enables it to be plugged into an iPhone to work with the dedicated, free app.

It transforms your phone into an ambient light meter, flash meter and colour temperature meter. But why would you use one?

Well, the ambient light meter is useful in tricky lighting conditions, or when your subject is dark or light enough to confuse your camera’s exposure meter. That’s because the Lumu Power is an incident light meter. It measures the light that is hitting your subject rather than the light it’s bouncing back.

Lumu Power review

Long Exposure and ND Filters

Helpfully, you can tell the Lumu Power which ND filters you have at your disposal. Then, after taking an exposure reading, you just need to tap the filter icon and select the filter that you want to use. This will then transpose the suggested exposure settings into the ones you need to use with the filter in place. That’s helpful for long exposures in daylight.

Flash Exposure

Just like a traditional light meter, the Lumu Power is very helpful in the studio when you’re using non-TTL lights. This option is activated by tapping Photo Flash  in the app’s main screen (shown below).

Lumu Power review

The next step is to set the exposure parameters. So, for example, set the sensitivity (ISO) and shutter speed that you want to use and tap start. Then, position the dome (still connected to your iPhone) over the subject, pointing back towards the camera.

Now tap the black Start button and fire the flash. 

The Lumu Power automatically detects the flash and measures its power, giving you the aperture value that you need to set on the camera, as well as a flash percentage power. You’ll get a warning if the flash is too bright. There’s also a graph that shows the flash duration, which is a nice touch.

Lumu Power Review

Colour Temperature

If you shoot raw files then it’s relatively easy to fix the white balance post-capture. However, if you have a long shoot, you can save your self a bit of time by getting it right in-camera. And your jpegs are share-ready. It’s also extremely helpful to get the white balance right in-camera when you’re shooting video. That could save you a lot of time in grading.

Colour temperature is measured in just the same way as light. Position the dome in the same light as your subject and tap the black on-screen button to take a reading. You can then set your camera’s Kelvin value to the one nearest the measured value.

Some cameras also allow a tint to be applied. Alternatively, you can make a note of the tint value (see later) and adjust accordingly in Adobe Camera Raw or Lightroom. The tint scale can be adjusted to suit various cameras or Adobe Camera Raw, for more information visit the Lumu website.

Lumu Power review


Helpfully, you can tailor the meter to your camera. For example, you can set the maximum aperture of your lens, the minimum exposure time and the maximum sensitivity (ISO) setting.

This is done via the controls icon in the top-right corner of the screen when a meter type has been selected. Consequently, you have to customise the settings for each type of meter that you use. That may seem like a duplication of effort, but it means if you use different cameras, or your requirements change with the shooting scenario, you can have a different set-up. 

Lumu Power review


Tapping the pencil icon in the bottom left corner of the screen when a meter is in use opens up a notes screen. This automatically records the last reading and gives the opportunity to open the iPhone camera app to take a record shot. If you like, you can also record the location using your phone’s GPS. 

Notes are accessed by tapping the pencil icon in the bottom right corner of the main screen.

These notes are especially helpful for colour temperature readings as it keeps a record of the tint, as well as the more specific Kelvin value than most cameras can set. It means you can make quick, precise adjustments in your raw file editing software.



The Lumu Power is quite expensive, but it’s a versatile little device. And actually, its price compares well with a modern dedicated light and colour meter but it’s more user-friendly than most.

It brings the once-essential light meter into the 21st century. Instead of fiddly buttons and dials, you get a slick app interface. It’s very easy to use. Plus, as it relies on an app, there’s scope for updates and refinements over time.

It also does its job well. I used it for several shoots and got good exposures and white balance. 

There’s no one feature that makes the Lumu compelling, but the combination of its capabilities makes it appealing. It’s the sort of device that you’ll find more and more use for. Many photographers have got out of the habit of using a light meter, or have never used one, so it’s natural that it might take a while for it to really bed into a workflow.

On a final note, it’s good to see a small case provided to keep the Lumu Power clean and safe. I’d like to have seen a modern material like neoprene or something similar used rather than leather, but each to their own.

How to shoot a deliberate over-exposure (or when to ignore your light meter!)

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