More than a Color Meter: Sekonic C-700 and C-700R SpectroMaster
When an industry leader like Sekonic, with more than 85 meters under its belt and a winning streak reaching back to 1951 presents a new “color meter” at Photokina just after the company’s 64th birthday, the photographic world takes notice. This, of course, is the company that put the tiny, ubiquitous L-308 in everyone’s pocket, sent the L-518 Digipro X-1 into space and presented the L-758 DigitalMaster as a hardware/software “Exposure Profiling” solution. So, when we were invited to take the new C-700 and C-700R SpectroMaster Spectrometer for Photo/Video/Cine for a test drive, we were more than eager.
The C-700 is not a Color Meter
Well, technically it is, but so much more. It’s like calling a Ferrari an economy rental; sure, it will get you from point A to point B, but then there’s this whole other world of possibilities. Don’t get me wrong—a color meter is a great thing to have and a lot better than guessing, especially with mixed lighting. It uses color sensors to sample red, green, and blue parts of the light source’s spectrum, and interpolates the light outside of the sample to be continuous, consistent, and emitted from a traditional full-spectrum, filament-burning source like tungsten, incandescent, or HMI. Things get dicey when measuring fluorescent or LED sources with different emission characteristics and more complex spectral profiles. In short, your color-meter reading tells you a lot about what’s visible to the human eye—but nothing about spikes or pulses that are invisible to the eye, but not the camera.
Enter the SpectroMaster C-700 Series, designed to address the needs of new and emerging light sources and the plethora of mixed sources used on set that demand up-to-date technology to match their capabilities and distinct color profiles.
Traditional Spectrometers read color in very “large” gaps of 10 nanometers (nm), and can miss crucial information like spikes and pulses that affect color accuracy negatively. The C-700 series incorporates a CMOS linear sensor, which measures and evaluates the color temperature of a light source from 380 to 780 nm in 1 nm increments, to give you a snapshot or unique fingerprint of the entire spectrum of the LED, HMI, fluorescent, flash, or halogen light source. Other meters, made for industrial use, offer lots of pretty colors and graphs but then what? Pull a scientist out of your pocket? The C-700 is a task-specific practical field tool that indicates real-time situational solutions and real-world recommendations to achieve your target temperature with minimal interpretation.
Boasting the capability of reading all light sources, including flash, the C-700/R SpectroMaster employs a 4.3" color touchscreen and nine displays: Text, Spectrum, Spectrum Comparison, CRI, Camera Filter, Lighting Filter, Multi Lights comparison, White Balance Correction, and Setting, to indicate the correct filtration needed to hit your target color temperature. There’s also a Toolbox button that gives you a very wide customizable range of choices over how your measured values are displayed.
To help you control ambient, flash, tungsten, halogen, HMI, LED, and other lights, the C-700 displays Correlated Color Temperature (CCT) in Digital mode and Photographic color temperature in Film mode to match the color spaces specific to each medium. Text, Spectrum, Camera Filter, Lighting Filter, and Multi Lights screens display corrective LB and CC filters for the camera or light source, with your choice of actual Kodak Wratten 2, Lee, Rosco or Fujifilm filter numbers, as well as LB/CC index numbers.
CRI (Color Rendering Index) is displayed digitally as an average of all colors in your source and on a 15-bar tonal display that indicates the individual CRI of each sample tone. In the Text Screen, illuminance and luminance (incident and reflected) readings for ambient light or flash light are displayed in lux, foot candles, or both. There’s a Delta button that, when pressed, shows the deviation from a previous or memorized reading for comparative purposes.
This might be a good time to draw the distinction between the two meters in the C-700 series. While they both have the same impressive specs, including both cord and cordless flash color reading, the C-700R (R for remote) has built-in PocketWizard wireless technology for remote triggering of a radio-slave-enabled flash or strobe, from distances of up to 100'. Neither is a “flash meter,” per se, meaning they don’t read flash in f/stops and shutter speeds, but instead recommend color-balancing filter solutions for your flash. The C-700R uses up to 32 meter channels. Channels 1-16 offer standard triggering, while channels 17-32 are called Quad-Zone Triggering Channels or MultiMAX Channels. These channels add A, B, C, and D zones that allow you to control up to four different groups of lights on the same channel. Each of these channels is on its own frequency and each channel number is its own 20-bit digital code.
In Depth: the Screens and Display Modes
The Main Screen offers nine icons for quick selection of many of the C-700 series functions at the touch of a finger. Speaking of touch, the screen responds to what might be described as a hard tap, which you’ll get the hang of in five minutes of use. This design was deliberate, since besides the light receptor, the meter is just about all screen. The hard tap prevents loss of settings as the meter is passed from person to person or hand to hand.
The Text Screen is, perhaps, the key to how the meter operates. At the top left of the screen, tapping a sunburst icon takes you to a Measuring Mode Screen that gives you a choice of Ambient Mode, Cord, or Cordless Flash Mode.
Tapping the small target window brings you to an alpha-numeric screen that allows you to enter your target color temperature (CCT) from 2500-10000K. The CCT that you set remains the same when switching to other display modes. The screen has five windows. Tapping any window takes you to a library of 10 measurement modes. Select one for each window. For example, you might choose to display Correlated Color Temperature (CCT), Lux, footcandles (fc), Light Balancing Index (LBi), or Color Correction Index, (CCi) values. Here’s the complete list of library choices.
CCT = Correlated Color Temperature
DeltaUV = Color Shift (from Kelvin Line)
CCi = CC Index Correction
CCcf = CC Camera Filter Correction
CClf = CC Lighting Filter Correction
LBi = LB Index Correction (Mired)
LBcf = LB Camera Filter Correction
LBlf = LB Lighting Filter Correction Lux = Illuminance (brightness)
fc = Foot Candles (brightness)
Whichever you choose, real-time measurements appear and are updated after every reading, next to their light-measurement values. Activating the Delta button after a reading is a great A-B comparison method. The button is active when it whites out after being tapped. Depress and hold the measurement button. Each window will display the differences in the new reading from the last. Keeping your finger depressed, you’ll notice (with mild delight) that the values continue to change as you reposition the meter until you release the button.
The CRI Screen
This is a bit of a revelation. A much-abused specification, most image makers don’t realize that the quoted and many times boasted CRI is an average reading; the large print, as it were, that hides some potentially disastrous small print. By way of explanation, the Color Rendition Index measures a light source’s ability to render tones of real-world objects faithfully.
The screen shows the above-mentioned average CRI (also called Ra) reading as well as 15 color-sample bars. CRI is measured using the first eight bars, while the remaining bars provide supplementary information such as saturation and contrast. Each of the Ra sample bars has its own CRI rating, keyed to its color. If you were shooting a scene that called for vivid reds, for example, you wouldn’t want to use a light with a red Ra value of 65, even if all of the other colors read 90+.
This particular screen is a great shopping tool for anyone in the market for lights and, in some cases, a guarantee of job security.
We tested two well-known LED panels that claimed accurate variable color temperatures between 3200K and 5600K and CRIs well above 90. We measured each light at both full tungsten and full daylight settings at 10, 50, and 100% light intensity. The test revealed that the “A” panel was true to its color temperature claims, but fell many points shy of its purported CRI, while light “B” had a higher CRI of 88 (still well under its published spec) and was also off up to 1000K in color temperature—more than justifying the cost of the meter. Anyone charged with purchasing a studio full of these lights without the benefit of C-700 backup might do well to fear the loss of his or her job, along with a loss of image quality.
Various other methods are in the works to supplant the CRI system of evaluation, such as the TLCI (Television Lighting Consistency Index) that replaces the human observer with a metric that measures light quality as it would appear on camera, on a scale from 0 to 100. Should that happen, Sekonic would simply add it to the C-700 with a firmware update, via the company website.
The Spectrum Screen and Spectrum Comparison Screen
This screen measures and displays the spectral distribution of light via a graph that can be enlarged to a full landscape screen to tell us, essentially, what the unique footprint of that source is. A lamp with “clean” tungsten light properties, for example, should display a graph with spectral energy that peaks at (780 nanometers) at the red end of the spectrum with very low energy in the blue and green end of the graph. There are three windows below the target color temperature that can also display the reading as data, such as CCT, lux, and fc or any of the nine measurement values in the data library, mentioned earlier.
Once again, the Delta button can be employed for fast A-B reading comparison, as it can in all of the measurement screens except Spectrum Comparison and Multi Lights, which are themselves multi-reading comparative screens.
Working much like the Spectrum screen, the Spectrum Comparison screen allows you to compare three different light sources. Ghost lines appear on the graph to illustrate two of the three readings taken.
Camera Filter Screen
Both the Camera Filter and Lighting Filter Screens have six value display windows. Your preferred values are chosen via the Setting Screen in the lower right corner of the home or measurement screen that appears when you turn the meter on.
The CCT window displays the current color temperature in Kelvin units, while the Brand window displays your choice of Kodak Wrattan/Lee or Fujifilm camera filters, which are indicated by name. The same principle applies to the LBcf (Light Balance Camera Filter) and the CCi (Color Correction Index) windows. A sample reading at a target color temperature of 5600K might be 4320K with corrective filters of 82C (blue) and 05 G (green) to hit that target. There’s also an LBi (Light Balance Index window, if you’d prefer to interpret Mired readings. The Setting screen gives you options of 1MK-1, 1 daMK-1 and 0.1daMK-1steps. For those who haven't committed Mired values to memory (nearly all of us) there's a chart in the included quick guide.
Lighting Filter Mode
Similar in principle to Camera Filter, the Lighting Filter screen also has five windows, except this time with LBlf and CClf (lighting filter) values displayed from your choice of Lee, Rosco Cinegel, or Rosco E-Colour+ filters lines.
So far we’ve been working in Ambient Light mode, but remember that both the C-700 and C-700R can read flash in cord or cordless mode. Although this will be addressed in detail later in the article, it should be noted that these choices can be accessed via the sunburst button in the upper left of the meter’s LCD screen.
Multi Light Mode (Comparison)
The Multi Lights screen is perhaps the most exciting (and coolest) to those who’ve tested the meter. The screen features A, B, C, and D windows with which you can record four light sources that you’d like to match or custom balance with each other.
For example, with my target color temperature set to 5600K, I measured three sources roughly in the tungsten range and one flash unit which, unfiltered, is daylight balanced in the blue end of the spectrum. Tapping the A, B, C, or D takes you to a measurement screen where you can read and record each light source as you proceed through to D, in which I recorded the flash reading. Tapping one of the blue radio buttons that appear next to each lettered channel makes it your main light and causes the other windows to display the LB and CC filters necessary to match that main light. You can memorize all of the readings and move on to the next group of lights you’d like to balance.
White Balance Correction Mode
This screen displays the difference between the current reading and your target color temperature in a white balance correction graph bordered by Blue, Amber, Green, and Magenta bars. Pressing the measurement button positions a red dot on the grid that indicates what sort of filtration will be needed to white balance to your target color temperature and center the dot on the graph. An LBi and CCi window above the graph tells you the filtration necessary to do it. Below the graph are BA (Blue-Amber) and GM (Green-Magenta) steps that are accessed via the Setting screen to allow you to adjust the size of the boxes within the grid to match the size of those found in high-end DSLRs and some video cameras.
The Setting Screen is not a measurement screen, per se, but it’s the key to how the measured values are displayed. This is where you set Shutter Speed Steps (1/3, 1/2, 1 step), LB steps, camera filter brand (Wrattan 2, Lee, Fujifilm) and lighting filter brand (Lee, Rosco Cinegel or E-Color). Other selectable values include White Balance steps, lux or foot-candles, illuminance, Spectrum Y-Axis Scale, Auto Power down timing, backlight level, radio system preference control (Standard or ControlTL) and choice of language (English, Japanese, Chinese).
Memory Recall Screen
The Memory Recall Screen is accessed via the Toolbox icon (image of wrench) on the main screen. Like the Setting screen, it is not a measurement display but rather enables selection of a specific Title and viewing of all stored measurements on each of the meter's screens. The Memory Screen also allows you to view and change the color space to Film or Digital, as well as name memorized values and select presets and radio channel zones.
Far from an “also included,” the Software Utility that comes with the C-700 meters allows you to access its features on a computer. You can view saved full color CRI, White Balance, and Spectral distribution graphs from a measured and memorized light source, as well as LB, CC, CCT, Illuminance and Ra data in text format.
The utility makes it possible to create a library of lights or groups of lights to monitor color shifts or other changes to maintain consistency, create duty cycles or to transmit to alternate locations on a given project for fixture color-matching. The utility also allows you to change current settings from the computer and access firmware updates.
Even for those familiar with color meters and, preferably, spectrometers, the C-700 is “a lot of meter;” there’s a reason the English instruction manual is 190 pages long. It’s clearly not made for everyone, but if you’re a director of photography, gaffer, lighting designer, textile manufacturer, museum/gallery conservator or anyone involved in an enterprise that requires precise and accurate spectral information, this meter is without equal. The C-700 could be considered next generation and maybe even the next two. It’s also an evolving instrument that can be firmware-updated with new information and features such as the adoption of new CRI standards. As Sekonic says about the C-700 in its product walk-through, it has “Everything you need and nothing that you don’t.”