Introducing Luxi - The Incident Light Meter Adapter for iPhone

From Kickstarter:

Luxi turns your iPhone into an incident light meter for photographers.

What is Luxi?

Luxi is a small diffusion dome that fits securely over your iPhone’s front-facing camera. When attached and used with a light meter app, Luxi will help you determine the best settings for your DSLR or other camera so that you can take perfectly exposed pictures.

What does it do?

With Luxi, your iPhone becomes a convenient and easy to use incident light meter. Professional light meters with the same features can cost several hundred dollars and require you to carry a whole separate device.

Incident light meters, like Luxi, measure the amount of light falling on the subject you are photographing, not the light reflected by the subject. Incident light meter readings are independent of the subject's reflectance and cannot be fooled by tricky lighting situations like back-lit subjects (e.g. sunset portraits).

Go to the Luxi Kickstarter page to see more.