Light meters are expensive but you’re bound to have an iPhone or iPad, so why bother? Some people develop light meter apps and the nec plus ultra of those must be Cine Meter II by Adam Wilt. I’ve tested Cine Meter II as a reflective and an incident meter.
Unique about Cine Meter II is that it starts from a filmmaking perspective. For example, the app has a waveform monitor, supports false colour brightness levels and uses shutter angles by default. Photographers, however, can easily change these settings and use shutter time in seconds and show EV values instead of frame rate.
The first thing you’ll have to do when using Cine Meter II is calibrate it with the help of a trusted light meter. This can be a Gossen, Sekonic or other “real” meter, or your camera’s built-in light meter. If you’re using the two cameras of an iPhone or iPad and you want to read reflective as well as incident light levels, you’ll have to calibrate the app four times. I only tested with the back camera of my iPad, so I was done after two — or so I thought, as I needed to also calibrate the colour and tint gain meters that drive the waveform monitor and colour temperature values and which work with the Luxi accessory only. The good news is that calibration was easy and quick.
For incident and colour measurements, I used the Luxi for All accessory from ExtraSensory Devices. This is a small, spring-loaded plastic dome you can use on any sort of tablet or smartphone. The Luxi for All allowed me to measure light falling on a subject (incident), instead of light reflected by the subject. The former is more accurate than the latter where specular highlights may interfere with your light meter’s readout. All you need to do to switch the two modes is activate the Luxi option in the Settings screen and tap the sensor button that also switches between front and back camera.
Using Cine Meter II
The Cine Meter II app is simple to use. You can switch from matrix to spot metering by just dragging over the picture frame. You lock exposure by tapping the Exposure Lock button, White Balance by tapping the WB lock button, etc. By default, Cine Meter II floats exposure — floating values change with the light while you set the other values. You can change that by tap-holding the Exposure button until the grey background switches to aperture, ISO or ND (neutral density filter).
The app’s Settings panel allows you to choose how you want to get your readouts. For example, exposure values can be set to highly granular levels, but also to full f-stops if you like. After having spent an hour learning all the intricacies of the interface, I was comfortable with how the app worked.
The litmus test came when I started measuring light values and comparing them with my Sony Alpha’s built-in light meter. For incident light values I have always used an ExpoDisc in the past. These are made of a bit thicker plastic than the Luxi for All’s dome, but I could easily test accuracy nevertheless. If differences between the Cine Meter’s readouts are consistently the same, you can safely conclude that it’s caused by the difference in density between the two.
Measurements were consistently what I expected them to be in reflective mode. With the Luxi for All dome, you need to keep in mind it’s the light falling on the subject you’re measuring, so here you need to go to the subject and measure light values from that spot. I did notice Cine Meter II with Luxi was quite sensitive to how I held the iPad. A few degrees away or towards the light source made a difference.
But if you use an iPhone, or iPod Touch even, you’ll probably run less often into this kind of minor difficulties as the device itself is less awkward to hold than an iPad.
To me, therefore, the Cine Meter II app combined with the Luxi for All accessory is an excellent, complete light meter replacement that offers all of the information you need with the accuracy you need, regardless of whether you’re shooting still images or video.