Cine Meter II Icon Cine Meter II for iPhone: how to... copyright © 2014–2017 Adam J. Wilt  
 
A cinematography-focused light meter with a waveform monitor and a false-color picture
 
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How To...

Exposure Measurement:

Visual Checks:

Color (requires iOS 8 or higher):
Automation:




  1. Use a tungsten light for calibrationvery important: calibration under LEDs, fluorescents, HMIs, and plasmas may give you inaccurate results.
  2. Take a color temperature reading with a trusted color meter. If you don't have access to another color meter, assume 2700 K for household incandescent lamps or 3100 K for motion picture tungsten lamps. This reading is your target color temperature for calibration.
  3. On Cine Meter II, tap and hold the color temperature and tint numbers at the top right corner of the display for 2 seconds to show the COLOR CALIBRATION panel:



  4. In Luxi (incident) mode, place Cine Meter II exactly where you took the reading with the other color meter. In reflected mode, aim Cine Meter II at a color-neutral target, such as a white-balance card or neutral gray card, placed where the other color meter took its reading.
  5. Adjust CCT: to your target color temperature: use the slider or the -|+ buttons (tip: you can preset the color temperature, then place or aim Cine Meter II as needed and tap SET). Whenever you drag the slider or tap +, -, or SET, you save the current value as the calibration, so make sure your final drag or tap is under your calibration light.
  6. Tap the color temperature and tint numbers at the top right corner of the display again to hide the calibration panel.

Tint is automatically set to 0 during calibration.

Reminder: Cine Meter II recalibrates whenever you adjust the CCT: controls. If you adjust the slider or use the -|+ buttons while Cine Meter II is not looking at the calibration light, be sure to tap the SET button under the calibration light as the last thing you do.

To Calibrate Tint Gain:

Using a tungsten light and a plusgreen or minusgreen gel:
  1. Tap and hold the color temperature and tint numbers at the top right corner of the display to show the COLOR CALIBRATION panel.
  2. Cover the Luxi (incident mode) or the camera lens (reflected mode) with your green or magenta gel.
  3. Adjust TINT GAIN: reading: aim for ∆ -30 with a minusgreen gel, or ∆ +30 with a plusgreen gel.
  4. Tap the color temperature and tint numbers at the top right corner of the display again to hide the calibration panel.
Using a household or industrial fluorescent light:
  1. Tap and hold the color temperature and tint numbers at the top right corner of the display to show the COLOR CALIBRATION panel.
  2. Take a reading under the nasty fluorescent light.
  3. Adjust TINT GAIN:  for ∆ +30.
  4. Tap the color temperature and tint numbers at the top right corner of the display again to hide the calibration panel.
You may find that setting a value of 30 gives you too much correction. Feel free to use lower values (even as low as 15 or 20) if those work better for you. You can adjust tint gain under any lighting: all you're doing is setting a gain value, so you can tweak it whenever you feel like it without disturbing other calibration values.

Here’s a step-by-step picture guide.

If you’re interested, here is a more detailed description:


Exposure calibration in pictures

Gray card
You'll need a flat, evenly-lit target, like an 18% neutral gray card.

reference meter
Use your reference meter to take a reading.

For best results, adjust your lightmeter's settings and/or the lighting so that you get an exact reading. In this case, I've set the ISO to 640 so that I get exactly f/8 at 24fps. (If you're using Cine Meter II version 1.1 or newer, which includes tenth-stop steps, this is less important as you can directly match Cine Meter II against any reading on a lightmeter that has tenth-stop steps.)

If you don't have a reference lightmeter, you can use your camera's meter instead. For the most accurate results, your camera should be in a normal gamma (e.g., STD, Rec.709, etc.), not Log, SLog, LogC, Cine-Like, Cine D, Cine V, V-Log, etc. If you're using a Blackmagic camera, it should be in Video mode, not Film mode.

Cameras may not give exactly the same reading as a stand-alone meter because cameras often “expose to the right” (opening up as much as a stop above what a separate lightmeter measures). If your camera has a histogram, see if you can adjust the camera so that the spike in the histogram is at the 40% - 50% brightness level for the most accurate results.

initial reading; matrix metering
Cine Meter II looking at the same target. Its view is too wide, so move closer, or use the zoomable spotmeter to see only the gray card.

zoomed in to read the gray card
I've zoomed in to read only the white-framed area (zooming turns on the spotmeter). Cine Meter II is reading 1/3 stop slower than my reference meter. (Note that I have Cine Meter II set for a 180º shutter to match my spotmeter's assumed shutter angle. I could also set the shutter speed instead of the angle, if my reference meter's setting used shutter speed.)

tapping Compensation
To adjust the reading, tap COMPENSATION.

Compensation slider
The COMPENSATION slider appears, with +/- buttons for fine adjustment, and a 0 button to reset it.
(If you're using Cine Meter II version 1.5 or newer, the slider also has a Cal... button.)

dragging to +0.1
Dragging the slider to +0.1 corrects the reading...

dragging to +0.3
...and +0.2 and +0.3 are also correct...

dragging to 0.4
...but at +0.4, the reading is now 1/3 stop too fast.

correct at 0.2
As +0.1, +0.2, and +0.3 all work, I used the middle value of +0.2.

If you’re using Cine Meter II version 1.5 or newer, simply tap the Cal... button on the COMPENSATION slider once you have your desired compensation. The compensation will be added to the current calibration, and compensation will be reset to zero. That’s it, you’re done; skip ahead to read about front camera and incident-meter calibration.

If you're using an older version of Cine Meter II, read on...

setting menu
Tap the button to open Setting and Info, and then tap Meter Calibration.

Meter Calibration
I've set Back Camera Calibration to 0.2 stop.

(If I already had a Back Camera Calibration value shown, I'd add my new value to it.)

clearing Compensation
Don't forget to zero out COMPENSATION once you're done!

meters match
Now, Cine Meter II's reading matches my reference meter.

calibrating the front camera
Calibrating the front camera is done the same way: simply stand behind your gray card so you can see what you're doing.

Alternatively, you can use a large, evenly-lit wall as your calibration target: sit or stand facing away from the wall, and aim your iDevice's front camera over your shoulder to take a reading.

Incident readings with Luxi or Lumu are best calibrated against another incident meter:

incident calibration

If you don't have an incident meter, you can use your reflected-light meter or camera's meter reading an 18% gray card, and set Cine Meter II's Luxi calibration to 1/2 stop less than your reflected meter reads. For example, if your reflected meter reading on a gray card is f/8, set Luxi calibration to read 5.6 1/2 (fractional half stops) or 6.7 (decimal half stops).

Color calibration in pictures

A 120W tungsten reflector flood

You'll need a tungsten (incandescent) light of some sort. You don't need a "movie light"; here I'm using a 120W reflector flood installed in a ceiling can in the hallway.

color calibration setup

Set up the calibration location. I've set up a folding table beneath the hallway light, and I've marked the precise spot I'll be taking readings at. This is important; the measured color temperature can vary depending on where in the "beam" of light you take the reading. In this case, I saw a 20 K variation in temperature from one side of the table to the other. I have my reference meter (Minolta Color Meter II) and an iPod touch with Cine Meter II and Luxi on the front camera. (Don't have a reference meter? Read on anyway!)

(If you're calibrating Luxi on the back camera instead of the front camera, it's best to stand in one spot. Look towards the light as you would when using Luxi on the back camera, and take your reference meter reading with the color meter held in the same position you'll hold your iDevice in.)

Taking a reference reading

Take your reference reading at the designated spot. Take several readings to ensure that you've got a good, average value; color temperature readings can be highly variable, so never trust just one.

If you don't have a reference meter, calibrate to 2700 K under standard household tungsten lamps (60W or higher); 2750 K with a bright household halogen lamp; or 3100 K under a “3200 K” motion-picture tungsten light. This assumed-value calibration won’t be perfect, but at least it’s likely to be more accurate than the uncalibrated reading. If you use this “guess your best” method, and you find the meter is still reading low (too warm), recalibrate under the same light at a higher CCT, e.g., 2800 K instead of 2700 K under household tungsten. If your readings are too high (too cool), recalibrate with a lower value, e.g., 2600 K instead of 2700 K. Repeat as needed until you find the target CCT value that gives you a good calibration.
 
Cine Meter II on the testing spot

Next, put Cine Meter II with the Luxi on the same spot. Make sure you're in Luxi mode, with the Luxi logo showing.

Tap and hold for the calibration panel

Tap and hold on the color readout to display the COLOR CALIBRATION panel at the bottom of the screen.

Match the CCT reading

Calibrate CCT: Using the CCT slider, +|- buttons, and/or the SET button as needed, set the CCT to the same value you got with your reference meter.

Calibrating Tint

Calibrate tint: cover the Luxi with a full minusgreen gel, and use the TINT GAIN slider, +|- buttons, and/or SET button as needed to get a reading of ∆ -30 (“30 M” on the main readout).

If you only have a half minusgreen gel, aim for ∆ -15 instead. If you use a full plusgreen gel, ∆ +30 or “30 G” is your target. If you have both minusgreen and plusgreen gels, don't be surprised if the gels give different numerical values. You can choose to split the difference (e.g., -25 for the minusgreen and +35 for the plusgreen), or just use the minusgreen gel for calibration.

If you don't have any color correction gels, take Cine Meter II to someplace with standard household / office fluorescent lights, and adjust TINT GAIN for a value of ∆ +20 to +30 (do not touch any of the CCT calibration controls when you do this; only use them under your CCT calibration light). Fluorescents vary in their green content, but +20 to +30 is a good starting point if you don't have any gels.

Setting reflected-color calibration

If you turn on Show Reflected Color, calibrate it by focusing on a gray card or white-balance card placed at your target spot. Use Cine Meter II's zoom function to focus in closely on it. For tint calibration, hold your gel in front of the camera's lens.

When you're done, just tap the color temperature/tint readout again, and the calibration panel will slide out of the way.



© 2014–2017 Adam J. Wilt.  Last updated 2017.04.18