Lumu Smartphone Light Meter
There's an old adage in photography, "the best camera is the one you have with you." The Lumu Smartphone Light Meter is the light meter manifestation of that ideal. It's extremely small, very accurate, and attaches directly to the smartphone you already have with you.
Lumu started as a Kickstarter campaign by Lumu Labs. After Lumu Labs met their funding goal they brought to market a well-made, well-supported light meter. In the box you'll find a Lumu lumisphere attachment, a handmade leather storage pouch that can attach to a camera strap, a lanyard you can use to hang the device around your neck, and documentation. Even though the Lumu is pricey for such a small, uncomplicated device, Lumu Labs have done the presentation justice and the included accessories add good value to the purchase.
The Lumu slots into the headphone jack on Android and iOS smartphones and turns those devices into a capable ambient light meter. As this light meter can only measure ambient light, you will not be able to use the Lumu with triggered flashes. Even so, Lumu Labs offers three free apps that let you run the light meter in photography mode, video mode, and pinhole mode. It's strange that they don't offer one app that simply switches between these modes, but alas, to have access to all the features you will need all three apps.
Adding to the convenience, the Lumu does not require its own battery. It gets its power from the headphone jack and has a nearly undetectable energy draw.
If you are looking for an accurate light meter to travel with, or just one to have handy when you walk about, assuming your phone is compatible with the Lumu apps, you can't go wrong with the Lumu Smartphone Light Meter.