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).
"I already have a light meter built into my camera; why do I need a separate device?"
The light meter built into all cameras measures reflected light. A reflected light meter shows an appropriate setting for an average of the whole scene. If you are taking a picture of a scene that does not have an average lighting situation, your camera's built-in light meter will not be accurate. Usually, that causes an overexposed or underexposed picture.
Sunset portraits and other pictures with strong back-lighting are common situations, and can be aided by using an incident light meter like Luxi.
Sample pictures using an in-camera light meter (L) and using Luxi (R)Sample pictures using an in-camera light meter (L) and using Luxi (R)
"My light meter app already has an incident mode. Why would I need Luxi?"
It is important to capture all of the light falling on your subject. Luxi is designed to work just like a professional incident light meter which can capture light from a 180° angle. When using a light meter app without Luxi, the iPhone camera only receives light from a limited angle which means it doesn't capture all the light. This will produce readings that are both inconsistent and inaccurate.
How to use Luxi with your camera
We have tested the Luxi and compared its performance against professional handheld light meters and got comparable results. The following picture shows a Luxi side-by-side with a relatively low-end Sekonic L-308 handheld light meter under even lighting conditions.
Light reading results of Luxi (L) and Sekonic L-308 (R)Light reading results of Luxi (L) and Sekonic L-308 (R)
Luxi makes a great companion for your vintage cameraLuxi makes a great companion for your vintage camera
Luxi created in CAD to prepare it for productionLuxi created in CAD to prepare it for production
