Color Meters:
How To Set White Balance With a Handheld Color Temperature Meter
A Color Temperature Meter is a specialized light meter that measures the color of light and gives you the white balance settings to use on your camera, or in your RAW editing software.
The color meter is not an exposure meter. Exposure meters measure the brightness of light and give you recommended aperture and shutter speed settings for proper exposure. Most color meters use three photocell sensors, each filtered for one of the three primary colors of light (Red, Blue, and Green). By comparing the amount of each color, the meter can determine the light's color temperature and the amount of Magenta-Green correction (if any) that is needed. The Sekonic C700 is a more modern color meter that uses a CMOS sensor, like a digital camera, which allows it to analyze the light's characteristics more accurately than a traditional three-color meter.
If you don't understand what Color Temperature and Magenta-Green Correction are, please read my Demystifying White Balance tutorial before continuing.
This tutorial will explain the different types of color meters available and will teach you how to use one to get accurate color when shooting digital.
There Are Three Types of Color Meters
Two Color Meters
The earliest ones, which came out in the 1950s, were Two Color Meters. The Gossen Sixticolor is the most commonly seen two-color meter, as it was made from around 1960 until around 1990. Two color meters only measure Red and Blue light. They can only give a Color Temperature reading; they cannot give a reading for Magenta-Green Correction.
I would not recommend one. They are useless for Fluorescent and LED light sources, which usually require some Magenta-Green Correction. Because none of them have been made for nearly 30 years, and many of them on the used market are MUCH older, many of them are out of calibration and can no longer be serviced due to lack of parts. The Sixticolor in my collection is not accurate anymore; and because it uses Selenium metering cells, it works poorly in low light.
Three Color Meters
Most modern color meters are Three Color Meters. Three color meters use three sensors, each filtered for one of the three primary colors of light: Red, Blue, and Green. These can read out both the Color Temperature and the Magenta-Green Correction (on the meters, this is called the CC value). They can be used for all light sources, and most can also read electronic flash.
Common examples of Three Color Meters are the Minolta Color Meter II, Minolta Color Meter IIIF, Kenko KCM-3100, and the Sekonic C-500. The Kenko KCM-3100 is actually the Minolta Color Meter IIIF. When Minolta stopped manufacturing photographic equipment, they sold their light meter division to Kenko, which renamed them and slightly changed the outside appearance of them.
These are all good meters, though I don't recommend the Sekonic C-500. Its low-light sensitivity is poor and it cannot read some incandescent lights because their color temperature is too low for it. I have one, and these issues have cropped up many times for me.
The Sekonic C-700 Spectrometer
The Sekonic C-700 is unique; it is a Spectometer that uses a CMOS sensor, like a digital camera uses, to analyze the light's spectral properties much more accurately than a Three Color Meter can.
Some of the C-700's features are fun if you're a geek like I am, but not really needed for photography. The best example being the Spectral Graph that it creates for each reading, so you can see what colors are present in what proportions in the light you're photographing under. This is actually useful for studio photographers, as it allows you to see if a light is capable of rendering accurate colors. Outside the studio, where we have to shoot with the light that is there, even if the light is bad, then we have to rely on the meter to give us white balance settings that will get us as close as possible to accurate color.
I prefer the C-700 over my other color meters because its low light sensitivity is very good, better than any other, and it is the most accurate one I have used.
Digital Mode and Film Mode?
Sekonic introduced a new feature with the C-500 that carried through to the later C-700 meters: a choice of metering for Film or for Digital. They gave little explanation about how the meters calculate their readings for the two modes, or how the readings would compare to those from other color meters, like the Minoltas, that do not offer these modes. I did extensive testing and comparisons of the two modes on my Sekonic meters, and compared them to the readings on my Minolta Color Meter IIIF.
I have not seen anyone else publish such tests, or give recommendations on how to use these meters for digital still photography.
So, What's The Difference?
First off, the film mode and the digital mode do give different readings on the Sekonic meters, so there is a difference between them.
The Minolta Color Meter IIIF gives readings that are nearly identical to those given by the Sekonic color meters when those meters are set to their Film Mode. Remember that the Minolta, and the Kenko KCM-3100 that is based upon it, does not have separate modes for film and digital. It just gives one reading.
So, the Sekonic meters in Film Mode are calibrated like most other color meters. Does that mean those other meters are useless for digital? We'll look into that on the next page.
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