The Luxi, created by Extrasensary Devices, takes the light meter app for iPhones one step further by adding an actual physical adapter. Professional hand held light meters tend to be bulky and expensive. Luxi is a small inexpensive adapter that manages to do the same thing as a professional meter – help capture a well exposed photo. The dome shaped diffuser fits over your iPhone’s front facing camera. Snap on the adapter, load the Luxi version of the “Pocket Light Meter” app and you have a hand held incident light meter.
Incident light meters like the Luxi measure light falling on your subject as opposed to reflective meters which measure light reflected from your subject. Reflective meters, like the ones built-in to digital cameras, can be fooled by bright, dark, or shiny backgrounds because they measure the light across the entire frame.
We’ve all snapped that photo of someone in front of a bright window and been disappointed with the results. The subject is an underexposed dark silhouette. Using an iPhone with the Luxi installed, move in close to your subject and accurately measure only the intensity of light falling on the subject, not the entire scene.
You can use your camera’s spot meter to try to match the results of an incident meter, but there are other variables that may interfere with reflective metering. Textures, ultra-reflective surfaces and even colors.
Extrasensary Devices successfully funded the Luxi project through Kickstarter platform and is now shipping the adapter for the iPhone 4/4S and 5. Priced at $29.95 there’s little excuse not to explore your metering options. You can download the “Pocket Light Meter” app form the App Store. Unfortunately, Luxi is not available for Android phones.