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

3.9 out of 5
134 Ratings

134 Ratings

sunchaser01 ,

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.

Maize4580 ,

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.

TheBurritoLord ,

The best light meter app on the App Store!

I tried almost all the light meter apps on the AppStore and none of them even come close to this one. Most of them are too hard to use. This one does what I want, you select your film speed, then either shutter speed or aperture depending on the look you want, and it gives you the other value! You can even see what the camera is seeing to make sure you aren’t intentionally pointing it at the brightest part of the scene.

Those people who are complaining don’t know how to use a light meter or what this app is for. This is only for figuring out your exposure if your camera doesn’t have a light meter. Most digital cameras already have one built in. This is primarily if you have a film camera that doesn’t have a light meter or it doesn’t work anymore.


Cole Imhoff
25.8 MB

Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.



Age Rating


  • Family Sharing

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

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