Lumu review: A clever and well designed light meter for your phone

The smartphone quickly became our most important device, we browse, make photos, play games, communicate and more on this little device. But, as if the smartphone wasn't multifunction enough, it can also be transformed into a light meter….enter our Lumu review.


A quick refresher


For those who don't know what a light meter is, check out this video. Long story short, a camera is a device that captures light. Too much light and you are overexposed, too little light and you are underexposed. To get an idea of how much light your camera needs to make an exposure, they have a device called a light meter to measure light.



Let the Lumus show you the difference! Image copyright the Lumu Team

That device is called a reflective light meter. It picks up light reflected off the objects. An incident light meter (and a Lumu is an incident light meter) reads the ambient light that falls on the subject (before it's reflected). It's considered more accurate than reflective because there's things that might throw off the reflective meter when it bounces of an object (Texture, etc)

*update: The new Lumu app now supports reflected light readings trough the phone's camera. Pretty cool!




I remember I had a Sekonic light meter, both an incident and reflective light meter built in. I loved it but really quickly I found some issues with it.
The first was that it was clearly overkill. Most modern light meters are meant for the studio and while it might be perfect for them, I wanted a simpler light meter. Just press a button, tell me what I need to know, I'm an available light shooter after all 🙂



The second was that a whole aspect of the light meter was redundant, the camera could read reflected light, why did I need an external one? The third an final problem, and it's why I got rid of mine was the bulk. It's an extra thing to carry and an extra thing to worry about. In my opinion it just complicated the photography process, in the words of my partner Don, it became an intrusion. I wanted a lightmeter but didn't want added bulk.


Lumu review


Enter the Lumu. Beats me where they got the name but it's fun. It's a lightmeter that uses a device that you already sleep, eat, drink and maybe shower with: your phone. Yeah sure, if you search for one you might find “light meters” that uses your phone's ambient sensor. But in my experience they are all jokes, at least when it comes from Android apps that I've tried.




The Lumu is compatible with any Apple device that run iOS 6. For android, these phones are compatible: Galaxy note 2/3, Samsung Galaxy S4/S5 and HTC One, they need to run Android 4.3 or later. The reason why the Android selection is limited is because of the hardware of the phones… you can guess the dome needsa soma powa and not every phone has enough juice flowing through the jack. Some unofficial reports state that it also compatible with the Moto X (4.4), HTC Evo (version unknown) but you will have to find out for yourself for these phones.




The Pareto principle (ye 80/20 principle) makes it so that you probably have a device that can handle the Lumu, the supported phones are the bulk of the market. Back to the Lumu, the whole thing is so well designed it makes me want to puke. Sheeeesh. It looks like something straight from Apple's Cupertino plant, the branding and packaging is top notch and impressive. Johnny Ives should hire these folks.




You get a nice metalic box with the logo nicely printed on….Yeah, ok..I'll stop nerding out on their branding. Inside is the necklace Lumu holder (did I say nicely designed? You can wear the Lumu around your neck and go out), and a little artisan pouch.


It's a bit hard a first to open and close the pouch but it gets easier as it get's used to it. Under everything there's stickers and cards. Fun stuff. The Lumu itself is a nice half dome with one part for the sensor and the back is of a grey or black finish that will look nice on any phone.




When you plug in your Lumu into the phone, there's a bit of distance between the phone and the light meter itself, it's to leave some space for your protective case if you have one….did I say well designed?




But looks aren't everything, if it doesn't work, it's a deco item. But it works as it should! The app is slick, designed with the typefcae helvetica neue ultra light….ok, ok no more nerding on the branding, promise! The app is sexy and uses the touchscreen effectively. Click on “Measure”, the device will do it's work, you've got 3 pieces of info: Aperture, Shutter Speed and ISO, swipe any of them and the app will tell you the new settings.




For those who like to shoot film, the app will let you add films and cameras, and then, at measurement time it lets you save the setting, some notes, a photo (for reference) and location. Very, very useful for film buffs.



You can change the background and have it blurred if you want. Second screen shows “notes” feature

Besides the exposure combo, the Lumu can also give you Lux and EV readings. It can display EVs in full, half and third stops if you need it. If your Lumu is off when you get it, you might need to calibrate it within the app (quick and easy). The app also allows you to compensate the exposure, from -2 to +2, great for overwriting the readings or pushing and pulling film. You can also have a filter compensation if you have one on your lens. Lastly, there's a dropbox sync feature to sync your notes about the info you saved with the app.


Lumu in the real world


What I like with the Lumu is that it's so minimalistic both in terms of software and hardware. Plug it in, put your setting, click measure, DONE. The thing is so small it can be left in your pocket, or you can use the small puch and attch it to your camera strap. It can be used anywhere to measure the light, it's a joy to use, unlike having to lug around an extra device. I used mine on my HTC One M7, one of the rare few Android phones that are sexy.


I went with it when I was shooting a small wedding -they're the best!- I had it on my phone-wallet and leaved it in my front shirt pocket. I used it many times to check the light, here to check the ambient light of where makeup was being applied:




And here, since I wanted a high key image, I put +1EV and metered (Didn't press measure yet, I only have 2 hands!):




This is the result:




And here I was making mental note of what the light was at 400 and 1.4, going down the aisle:





Evidently these settings would not work for me at 1/15th! But I knew I would be ok near the Altar where there was more light. Last shot:




Of course, with that thing in my front pocket many asked what it was, mistaking it for a credit card reader.




At the end of the day, the Lumu is a well designed and well thought of device. I used it for professional purposes, and will continue to do so, but I like it so much and it's so useful while being so small, I'll use it for many things, portraits, street, etc. If you have a compatible smartphone, I highly recommend the Lumu.


Where to get it


Get it from Lumu by clicking here. It's $149, comes in sliver and black. It ships from Slovenia but shipped quickly by DHL, got mine in a flash.


About the reviewer

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15 thoughts on “Lumu review: A clever and well designed light meter for your phone”

    1. Looks cool. But if I’m understanding correctly, the camera is the one that meters through the dome? A test needs to be done to determine the accuracy. Thanks for sharing the link!

  1. Pingback: Lumu review: A clever and well designed light meter for your phone | Olivier Duong › By TOMEN

  2. I can see if you don’t own a light meter, this could be useful. But if you do, why? It is still something extra to hang around your neck or put in your pocket (something you can do with a real meter. And the biggest problem here are the reflections and light you will get off the massive phone screens. There is no way this won’t affect your readings. For the same price you can get a small dedicated light meter.

    1. I understand, it would be redundant if you already have one. For the screen issue, you can always turn the dome, and surprisingly enough, I’ve seen it compared to Sekonics and it’s spot on 🙂

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