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News & Insight

Why You Want A Dedicated Light Meter & How to Turn Your Phone Into One With Lumu

By Kishore Sawh on July 12th 2014


As perhaps one of the last pieces of equipment newer photographers think about getting, especially in digital, light meters perhaps don’t get quite the appreciation they should. Granted, in-camera metering has become quite a bit better over time (depending on camera model), and histograms on your LCD help to see what’s really going on, but a dedicated light meter accomplishes its job with more accuracy, finesse, and I believe, teaches you to be able to read light better.

They can be, frankly, unnecessary for most occasions of a more casual nature, and if that’s mostly what you’re dealing with, then the expense of a dedicated light meter may have you neglecting one. Then, of course, there’s having yet another piece of gear to carry. Lumu, is a company/product that brings light metering to your smartphone. It’s effectively the lumisphere (actual reader) that plugs into your phone much like a Squareader does, and combines with its software to turn your phone into an elegant, easy to use interfaced light meter.


It was born of Kickstarter, and while most Kickstarter photography products are a bit rubbish, this doesn’t seem to be, and by user accounts, it certainly isn’t. Fully funded and in production thanks to the good-faith of funders, the product ships in style, with its own beautiful case, a neck lanyard option, and software to be downloaded is of course, included. There are two apps available, and though one is for typical purposes, they’ve included a second app which is for pinhole photography. At $149, it’s around the price of many good light meters, and not nearly as much as some, which can run into hundreds. And it’s tiny, so it can go anywhere.


Currently only available for iOS, it’s coming soon to Android. You can see more of it and purchase here, and get the Apps here.

[REWIND: Curves | How To Get The Most From The Adjustment Tool You ‘Think’ You Know]

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A Short Word On Light Meters vs In-Camera Light Metering

Understanding the value of a light meter requires a small touch of insight into light metering itself and how the devices work. Your DSLR measures reflective light, which is the light that bounces off the subject and hits back into the camera. This is great in a way since you can meter from a good distance away, and does a decent job taking in an entire scene, but it’s limited. Strong variances in brightness and color can trick it. DSLRs also can’t meter for strobes/flashes precisely.

Incident light is the light as it falls onto the subject. This is why when using a light meter on a face, the meter is held at the face with the lumisphere pointing in the direction of the light. This is the better choice, that’s more true. Dedicated light meters can do both incident and reflective, and you can measure strobes individually. This way you can record settings which will allow you to recreate a look easily in a studio, for example.

Another great benefit of a dedicated light meter is the it will help calibrate your eye, and mind, to light in any particular environment. You’ll be able, after a while, to better judge required settings for proper exposure without having to meter, with great accuracy.

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A photographer and writer based in Miami, he can often be found at dog parks, and airports in London and Toronto. He is also a tremendous fan of flossing and the happiest guy around when the company’s good.

Q&A Discussions

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  1. Ian Moss

    Ah – thanks for the link.

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  2. Levente Nagy

    Here is a video Lumu did that compares their meter to others:

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  3. Talwin Davis

    If anyone has used this, how reliable and accurate is it. I would definitely be interested in it but would like to here more from photographers that have actually used it. It would be a practical and cost effective option versus the traditional light meters (well at least in my mind)

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  4. Tor-Ivar Næss

    I backed this project on kickstarter. I really should use it more, so that I’ll learn it’s true value…

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  5. Emilio Savov

    I’d love to have one once they make it for Android. It’s always good to have a light meter other than the built-in in the camera.

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  6. Ian Moss

    Interesting as an ad’ for the product, but not that useful to a potential buyer. How well does it actually work? How do the light reading vary in accuracy from the camera meter? And in a economy where you can buy a Weston V for less than a third of the price, is it worth the money?

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  7. Keegan Carroll

    Looks great!

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  8. Joshua flowers

    Been thinking about picking up an old film camera and this would be perfect.

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  9. Michael Chapman

    Nice article that keeps us informed on one of the latest developments and gear – thanks!

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  10. John Cavan

    This looks like it would work very well for available light measurements, but a big reason many of us drop the money on a meter is to measure and coordinate strobes. I don’t see how it could trigger those without also being able to trigger the camera. They might want to touch base with the Camranger folks, that would coordinate quite nicely.

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    • Kishore Sawh

      John, all true things. Available light would be what to use this with, and I think the market they are going after is precisely those types. Interesting about Camranger

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  11. Anthony McFarlane

    I have this light meter and enjoy using it when I pull out my old nikon film camera!

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    • Kishore Sawh

      Anthony, you do have one huh? Glad to hear you enjoy using it. I’m very intrigued about its performance but the majority of what I’ve read has been positive. I may have to get one just to tag around with me.

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    • Anthony McFarlane

      Yeah I was one of the first round of supporters of the project on kickstarter and had to wait way past the promised delivery date once it was over. At one point I was nervous and did not think it was coming and then it arrived. I use an android phone and it seems to work just fine. I have only shot one roll of film and just about to start another series of images. So far it seems fine. I should mention this is my first light meter so I have nothing to compare it to.

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