Rosco Plusgreen: The Magic Sunset Filter

Druids may get all festive around Winter Solstice, but you can bet your typical cubicle worker is equally pissed off. That's because most of them arrive at work barely after sunrise, and don't leave until after dark.

For that same reason, it is also when architectural photographers are most willing to go out and freeze their nu brave the cold weather to make skyline shots. At least in the northern hemisphere.

Buildings with their lights all aglow at mix light are much prettier than they are at mix during other seasons. In June (at 39 degrees north, where Baltimore is) you'd have to wait until 9:30pm to get this shot. And the buildings are mostly empty and dark by then.

Mix light is wonderfully unpredictable when it comes to the color of the ambient. And on top of that variable, here's a little tip courtesy the architectural photographers: When you shoot dusk skylines, try a few with your camera set to the FL white balance as in the example above. (Click the pic for a bigger version.)


Because it does two things. First, it cleans up the indoor fluorescent lights in your photos, taking out a lot of the grody green cast. And second, it adds about 30CC of magenta to whatever your post-sunset ambient light is doing. Even though I shoot in raw, I always shoot it in daylight, tungsten and FL balance just to get a feel for which one I might like the best while still on the scene.

Okay fine, Building Boy. What's all this this got to do with lighting?

A lot, actually ...

Take this key-shifted portrait of a man on his boat. (See: On Assignment.) By taking an orange CTO filter and sticking it over your flash, you can shoot on tungsten WB and add a lot of blue into the sky. And it really gets cool if you underexpose the ambient one or two stops.

Similarly, you can do the same thing with your green FL conversion gel. By sticking that on your flash and shooting on FL white balance, you effectively add magenta to your scene. Which takes a "meh" sunset and makes it look pretty cool. Or turns a good sunset into something almost alien.

So not only do your skylines look amped on FL WB, but you can easily shoot a portrait in that shifted environment if you wish. Just green your flash.

And as always, you can change the look and intensity of your new +30M CC sunset by over- or underexposing it. So work that shutter speed for a range of looks.

These two filters (CTO and PlusGreen) are special because they are calibrated to be offset (or, very closely so) by your camera's respective white balance settings. Which means you can zero them out, leaving only your unfiltered ambient in that completely different color space.

Tip: Many cameras offer several different white balance settings to cover the wide range of colors of fluorescent light. You can also customize it by tweaking the white balance warmer or cooler. Photograph a neutral scene with only strobe light and figure out at which "FL" setting your camera best matches a Plusgreen filter. Then write it right on the edge of your filter.

That way, if you need to inject some color into a sunset and balance a green-gelled flash, you'll know right where to go with your custom WB.

Finish it Off

Remember, this filter-based color key swap only gets you back to neutral white light in your flash-lit areas. You are probably going to want to add a little warmth on your key light in a portrait to make them pop. Try a 1/4 CTO if you shoot Nikon (or a Rosco 08 if you shoot Canon as they tend to be a little more red sensitive.)

Even if you just have the $10 Rosco Strobist kit (more info | where to buy) the good news is you already have five copies each of these heavily used gels, and several more.

But if you are only using that Plusgreen to fix your fluorescents, you are missing out on a very cool use for them.

And if you live in the southern hemisphere, file this one away for next June 21.


New to Strobist? Start here | Or jump right to Lighting 101
Got a question? Hit me on Twitter: @Strobist
Have a passport? Join me in Hanoi: X-Peditions Location Workshops