Lux turns your iPhone or iPad into a professional-ready and convenient light meter for film photography. The first light meter on the App Store to use metering data directly from the camera sensor.

Note: Lux is designed for use with a separate camera. This app does not take digital photos.

- Live preview with tap-to-focus produces metering to match the image as displayed on your iPhone or iPad

- Accurate, fast metering data directly from the camera sensor

- On-screen controls provide instant feedback atop the live preview

- Supports full stops, third stops and half stops

What's New

Version 1.4

- Minor bug fix

Ratings and Reviews

3.7 out of 5

53 Ratings

53 Ratings

Solid App but...


Maybe I missed it but I don’t see an action/input setting for focal length of the lens. If you were shooting 35mm on a full frame sensor DSLR, the ISO, shutter speed and f/stop would be different than if you were shooting a 200mm lens. The longer the lens, the further the light has to travel requiring the photographer to compensate with a higher ISO, slower shutter and higher f/stop number (smaller shutter opening). Another thing to consider when using the DSLR is the sensor size. You have full frame DSLR (true 35mm) and cropped sensor. Between Canon and Nikon the crop percentage is a 1.6 and 1.5x respectively. This means if you have a Canon 5D Mark III and you are shooting a 100mm lens, that lens is fitted perfectly as if it were a true 35mm camera therefore allowing you to shoot at exactly 100mm. Now if you take that same 100mm lens and place it on a Canon 70D or 7D Mark II, the cropped sensor will come into play causing the cropped sensor to magnify the lens focal length by 1.6 and therefore allowing you to shoot that same 100mm lens as if it were a 160mm lens on a full frame or 35mm camera. Also cropped sensors are smaller which will require more light than a full frame. Instead of an ISO of 400, you might need an ISO of 640 or 800. Hope this was helpful. Nikons crop percentage is 1.5 while Canons is 1.6.

Good quality app


First: disregard anyone that says you need to input a lens or sensor/film size, they don’t understand photography. The beauty of the aperture system is that at a 2.0, the same amount of light reaches the film plane whether the lens is a 20mm or a 200mm!

Second: this really is a great app, but in all of my tests, it is 1 stop underexposed. I checked this against several film camera meters, my Pentax K-1 full frame and my K3 apsc camera.

Knowing it is 1 Stop underexposed, I can use this with my old cameras that have no meter and get great results. If it calls for an aperture of f16, I use f11 and it’s spot on.

Best in field for metering scenes


Form follows function. Clearly built by someone who knows exactly what's needed in metering a scene for "making photographs." Parallels standard camera exposure control factors with appropriate intermediates and limits. Tapping points in scene reveals necessary exposure for resolving shadows and highlights. Smart, straightforward interface, app does its job and gets out of the way. Very nice work.


Cole Imhoff
25.8 MB
Photo & Video
Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© 2014-2016 All Rights Reserved.


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

You May Also Like