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
71 Ratings
71 Ratings
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.

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.

John f tx ,

Good substitute for a $500 spot meter

If you shoot film, you must have a digital spot meter. There's really no other good option. This app is right in line with my Sekonic $600 meter and my
Pentax digital spot meter.

You can easily switch it from a small spot to a larger averaged amount: it will do aperture priority, shutter priority, or film speed priority. It's truly remarkable.

It's important to understand that this is a complicated instrument. It's designed to be used by photographers who know How to use a meter and how to expose film.

I have it it's a great feel safe back up in case a meter fails In the field that I would not hesitate to use it.

Most people can't afford a dedicated spot meter: this is a great alternative.


Cole Imhoff
25.8 MB
Photo & Video

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



Age Rating
Rated 4+
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  • Family Sharing

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

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