Cine Meter II Icon Cine Meter II: Brightness Correction copyright © 2015–2022 Adam J. Wilt  
A cinematography-focused light and color meter with a waveform monitor and a false-color picture

Adjust Brightness Correction (requires version 4.0 or later): Some iDevices introduced after mid-2014 (iPhone 6 and later) are too sensitive to bright light: at high light levels, such as outdoors in full sunlight, Cine Meter II may read up to 2/3 stop too high. This should not be a problem for any iDevice with an A11 or later processor running iOS 14 / iPadOS 15 or later, but iDevices with earlier processors may be affected. This “brightness bump” is a small error, but if it bothers you, you can correct it.

How to see if it affects your iDevice: Take readings with Cine Meter II and compare them to the readings from a different metering device (a light meter, DSLR, mirrorless camera, or video camera). Your iDevice’s front and back camera may be affected differently, so test them individually.

What to do if you see a brightness bump:

How to correct the brightness bump: Cine Meter II’s Brightness Correction panel lets you set the starting and ending brightness values (BVs) for the brightness bump, and the amount of correction to apply. To use it, match Cine Meter II to a reference device (another light meter, DSLR, mirrorless camera, or video camera) at a low light level, then compare the readings of the two devices across a range of brightnesses, from low to high.

Example with both meters reading in decimal third stops. In reality, you will see more variations in your readings. Small variations are normal and are to be expected: the two meters’ readings may not change from one value to the next at exactly the same brightness level, and your iDevice’s bump may not be as well defined as shown here. The values shown are for illustration only and may not line up with the same brightness values in your measurements.

The easiest way to generate a controlled range of brightnesses is with a motion picture lamp in a dark room. I’ve used a 30-watt LED panel and a KinoFlo Diva-Lite 400 with good results.

You can test using either incident or reflected readings. Brightness correction is different for your iDevice’s front and back cameras, but it’s the same for both incident and reflected readings using the same camera.

For incident readings: start far away from the lamp and move closer to it to increase light levels, aiming both meters directly at the light and taking readings as you go.

For reflected readings: set the lamp close to a white wall, washing the wall with light, from dark to bright:

Wall wash with 30 watt LED. Blue tape dots at one-stop or half-stop intervals help when aiming meters.
You can also stick a tape measure on the wall to use as an aiming target.

Aim both meters at the same point on the wall, aiming far from the lamp for low light levels and closer to the lamp for higher light levels. (Tip: when testing with a camera, use a zoom lens on the camera and the zoom setting in Cine Meter II to focus them both on the same small area of the wall.)

Step-by-step instructions:

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© 2015–2022 Adam J. Wilt.  Last updated 2022.08.06