When I wrote my book on LED lighting the two color panels were scarce. Recently, cost effective panels with a mix of tungsten balanced and daylight balanced bulbs have become more readily available. I bought one of the Fotodiox 312AS panels recently from Amazon.com for $158. It came in a soft case along with a diffuser panel that attaches magnetically to the front of the light, two lithium batteries that are generic copies of popular Sony camcorder batteries, and a two bay battery charger.
The panel has two rotary knobs on the back. The one on the left controls the balance between the daylight bulbs and the tungsten bulbs. Rotate all the way counterclockwise and you have 3200K light. Rotate all the way in the other direction and you have 5600K lighting. Somewhere in the middle you have full brightness from both sets of LEDs and a color temperature somewhere in the mid-4000K region. Be aware that while the color temperatures very accurate the hue is still somewhat green. Nearly every LED light, even the costly ones, require a little bit of help to cancel out the green color cast. A simple plus 1/4 magenta filter works wonders.
I used this panel and two smaller single color panels (daylight) to do an assignment this past week. We needed to shoot a portrait of a key executive for one of the world's largest manufacturers of semiconductor fabrication equipment. The assignment was a two part project. We would be setting up two different areas and taking the person's portrait in each of the areas. The brief called for a standard formal portrait and an environmental portrait in their very large server farm. Think thousands of square feet of server racks, each filled with blade servers....
We would have the executive for a very limited amount of time so we scouted the location several weeks earlier and came equipped to handle two very different lighting situations. I arrived two hours before our start time in order to set up and test both locations. Then, when we started making portraits we would be able to move quickly from our first set to our second set and maximize the time we would have with our subject.
We set up the formal portrait in a very large, windowless training room. It was perfect. High ceilings and lots of uncluttered, linear space. I lit this set up with three Elinchrom monolights and various lighting modifiers. I shot with a Sony a77 camera and a 70 to 200mm f2.8 G lens. While it's a fairly new camera system for me the lighting is old hat and fell into place quickly. I was happy to have 60 feet of front-to-back space available; it let me light the background totally separate from the foreground and that gave me more control.
The second set up was in the server room. When I scouted the location I saw that the entire room was lit by ceiling mounted florescent light tubes. At the time I took a test shot with my small Olympus EP3 set at daylight and when I got back to the studio I took a good, hard look at the lighting spectrum. An approximate light temperature of 4200 with about 16 points of green. The green spike wasn't much different than the green spike in the new Fotodiox light and I knew that if I used it without any filtration my only task to get a good match for the actual color temperature of all the light bouncing around that room from the florescents fixtures.
I used the Fotodiox as my main light and diffused it through a Westcott Fast Flag 24 by 36 inch collapsible flag/panel. The final step was to rotate the color temperature knob and find the sweet spot with a person standing in at the same spot as our executive would stand in. With the main lights locked down I added two kicker lights by using 160 LED fixtures with no correction. I didn't mind if the small amount of accent was bluer as long as it didn't introduce a different color spectrum.
The main benefits of using the new LED panel as a main light were the ability to use it without a power cord and an extension cord in the server room, with the quick twist of a knob it was a nearly perfect color match for the acres of existing lighting, and I could increase or decrease the intensity of the light with the second knob. I used another Sony a77 camera, this time with a 50mm 1.4 lens on the front, to shoot all the portraits in this location. I settled on ISO 400 as a good compromise between being able to go handheld if I wanted to and still provide a noise free file. The "teardown" in the server room took only a few minutes after the shoot. Then I headed back to the training room to disassemble and pack the flash gear.
Now we have an executive photo gallery with two totally different looks. The global color correction (all that was required) is right on the money and the clients are happy. These multiple set up jobs happen more often than you might think making it a good idea to have enough light stands, lighting units and support hardware in inventory to pre-set two or three locations for near simultaneous use.
The light from the Fotodiox 312 AS is brighter than the previous generation of small LED panels and the artistic potential of total color temperature control is intriguing. After the shoot, and after looking carefully at the files in post (24 megapixels at 100 %) I went online and ordered myself another unit. In a revival of my previous Minimalist Lighting enthusiasm I can now see going out on portrait assignments with two of the 312 AS lights to use as mainlights and a handful of 160 LED units for backgrounds and accents. Those and little bag of batteries would work well in nearly every situation short of having to shoot with sun drenched windows and exterior daylight in the frame. In all, a win for me and my clients.