Luxi Turns your iPhone into a Light Meter for Cameras

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Just a little less than a year ago I got my first DSLR camera – well actually the Nikon 1 J3 is a mirrorless hybrid camera, meaning that it has interchangeable lenses and takes photos like a DSLR but it is much tinier more like the size of a point and shoot.  Most of the time I admit to just using the automatic mode, because it’s easy, but I know that I could get much better pictures by putting it into Aperture Priority, Shutter Priority or Manual mode; my problem is I’m dismal at figuring out how much exposure I need in different lighting situations and when shooting in those modes my pictures are generally lackluster.

Extrasensory Devices announced the release of the Luxi, 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.

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).

To be honest, the Nikon 1 J3 does a pretty good job of mearsuring the lighting in most situations on its automatic setting.  But knowing that I can use the Luxi to let me shoot in a different mode and still achieve proper exposure had me interested and so I tried it out.  I still have a lot to learn in my overall settings but here is how it works.

While having an app engaged, you hold the iPhone with the Luxi attached right up next to the subject so that the light meter’s sensor is facing the camera that will be taking the photo.  The app will then give you a shutter speed and f-stop, with a given ISO value to get you the proper exposure.

Just to give a comparison this is a reading I got from using the Luxi and an app.

While this is the one my automatic camera settings gave me.

You can see they are close but the Luxi was capturing a different amount of light than the camera did which could be due to reflection light that the camera sensor was metering.  Which is the exact reason you want a light meter for exposure!

With Luxi settings on Manual mode with the Nikon 1 J3. 

Automatic settings on the Nikon 1 J3. 

I found there was a learning curve to using the Luxi, I didn’t receive any instructions with it and the short video on their website and the FAQs didn’t really help me much.  I found calibrating it a bit confusing with their own app but I think I eventually got it to the setting I needed it at when I switched to an app called Pocket Light Meter.  I just found Pocket Light Meter’s app more intuitive for me.  I think for me the real issue is that I’m still not yet entirely sure what ISO to be shooting at in different lighting levels.  While you can certainly use it if you’re on your own, your photo shoot will go much faster if you have someone else with you that can work the iPhone Luxi metering while you stay behind the camera 😉

I know it’s just a matter of practice and trial and error though before I am using Luxi like a pro!

The Luxi sells for $24.95, which makes it a HUGE savings compared to most light metering equipment and doesn’t take up any space.  It comes with a wristlet so you can have it handy all the time and a microfiber pouch to store it in when you aren’t using it.  Luxi is available for the iPhone 4/4S and 5/5S at

Do you use light metering equipment when you take photos, or do you rely on your camera’s automatic settings?

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