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.


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Blogger Eric said...

I miss film where you could just double expose with the CC30 an hour later...

December 20, 2010 11:58 PM  
Blogger IsaacMTSU said...

Now we need some example photos of that Plusgreen key light being corrected to white

December 21, 2010 12:34 AM  
Blogger David said...


Excellent! I knew someone would volunteer. Just drop a URL into the comments.

Many thanks!


December 21, 2010 12:45 AM  
Blogger Keith Woodhall Photographer said...

Great post as usual. Two questions regarding gels.
1. What is the cheapest possible way to buy the stuff? The roscoe sampler is great for speedlights, but I am looking for the cheapest solution for alien bees.
2. If I found an interestingly colored piece of plastic transparency, Say...neon pink, could I just use a grey card to get my added light back to white in post? I'm guessing it would have to be hit with the gel'd strobe pretty directly.

I suppose A custom wb in camera would work for this as well.


December 21, 2010 2:02 AM  
Blogger Tripp said...

What about those of us who live on the equator? We get the shaft all the way around! No changing seasons, 12 hours of daylight year-round, and when the sun sets it sets FAST!

December 21, 2010 7:46 AM  
Blogger Ido said...

When you mentioned the green gel to balance the fluorescent light with city lights, at first I thought of Gregory Heisler's photo of Rudy Giuliani, but in that he uses the plusgreen in the opposite direction, to simulate the green fluorescent light. Oops.

Thinking of the winter solstice, I went out to take a photo of the lunar eclipse last night, and I thought it would be nice to make the stars brighter. Bummer! Can't put a speedlight behind the moon to make the stars brighter. My brain isn't working.

Is there life before coffee?

December 21, 2010 11:10 AM  
Blogger Chris said...

At least you can plan on shooting at the same times every day, even if you have to stay up a little late ;-)

December 21, 2010 12:51 PM  
Blogger Matt Kolberg said...

You can still do a double exposure in a similar way, albeit digital with two files. The results would be the same.

December 21, 2010 1:07 PM  
Blogger Steve Kalman said...

What is the quality difference between shooting with various white balance settings vs shooting and changing WB in ACR? (Assuming Raw, of course).

I understand that adding a gel can't be done in post, but even that raises a similar question. If I gel the flash but don't change the WB, can I fix it properly in ACR?

December 21, 2010 1:37 PM  
Blogger Brian said...

I like the idea of figuring out exactly what WB FL setting goes with your PlusGreen gel, but isn't the amount of greenness (and related WB tweak) totally dependent on flash power/exposure? Do you just go for the middle ground, say 1/4 power at 10 feet for the optimal WB tweak to note on the gel?

December 21, 2010 2:57 PM  
OpenID hcwilliams4 said...

Keith: I bought gel packs for my Alien Bees at They don't list the products on their website but if you use the contact form on their site and ask for a specific gel pack at a specific size, they will quote you a price.

December 21, 2010 3:01 PM  
Blogger Stefan said...

Hi David,

first off all I have to say thank you for your blog.
If you are looking for examples please have a look at:
and there go to:
cars - Audi(click first small pic) and scroll to the right until you see a nightshoot of a grey Audi TTRS.
The Flashes were geled blue and the camera was set on individual color balance to get the car neutral and the Background more yellow.
You will find much more pics that were made like this, some more subtil, some more obvious.

It´s always a great inspiration to see you blog. Thank you.

Have a good time and
MERRY CHRISTMAS to everybody


December 21, 2010 6:03 PM  
Blogger RexGRP said...

I haven't had good results using Plusgreen or Windowgreen for digital capture. Worked well with color neg back in the day.
Maybe flourescents have changed. I use a more yellow filter a lot and rely on the flavors in my well-used set from

December 22, 2010 12:01 AM  
Blogger Darren Whitley said...

I photographed a surgeon yesterday and used a blue gel on my background light. Trouble is/was that this light create some undesirable shadows from the surgical lamp arms on the ceiling.

Is there a way I could color shift the foreground and get the background to shift blue without this background light? The low level of ambient background light was orange. Adding an orange gel to the strobes would get me close to a match... doubling the orange and filtering for it with Kelvin WB, wouldn't that shift the background to blue?

December 22, 2010 1:07 AM  
Blogger David said...


FL's have most definitely changed. The new warm white ones are like an old FL and a tungsten bulb combined.

I posted about this in Oct:

December 22, 2010 1:22 AM  
Blogger Paul said...

@hcwilliams4: Wow. Just checked out the site you mentioned. for strobe sized gels, they charge $17 for a set of 18 filters, whereas most places charge $10 for the Rosco Strobist kit which contains 55 filters. I can't say a price differential like that would entice me to shop for anything else there.

December 22, 2010 10:35 AM  
OpenID hcwilliams4 said...

Their gels are quite a bit longer than the ones in the Strobist pack so you can use velcro to attach them. The only attachment devices I've found for the Strobist gels are the gel holder from Lumiquest or a bent piece of acrylic, both of which add another $10-$20 to the total.

December 22, 2010 12:04 PM  
Blogger gibbonsp said...

I use this method all the time for the Zombie Crawl. All of the photos in this gallery were not modified, other than by dragging sliders in Lightroom and adding the border in Photoshop - - all of the effects were done with colored flash, like you're talking about. Great article!

December 22, 2010 12:39 PM  
OpenID d-word said...

If I understand Isaac's request correctly, I believe a good example is Joe McNally's photo of basketball player Bruce Dalrymple on page 66 of The Moment it Clicks. The shot is fluorescent balanced with the flash gelled green to match the fluorescent light inside the train. Here's the only link I could find:

That photo is one of my favorites in the book.

December 22, 2010 1:15 PM  
Blogger mstrubbe said...

@Keith One of the most affordable way to purchase gels for your Alien Bees (or any light larger than your speedlight) is to buy the gels in sheets and cut them down to size. B&H (as well as other photo retailers) sell Rosco gels in 20x24 sheets for $6.50 each plus shipping. I usually chop them down to get 4 10x12" inch pieces from one sheet.

Buy what you need, not what you don't.

December 23, 2010 12:40 PM  
Blogger Keith Woodhall Photographer said...


That sounds like the best deal. Thanks for the info.


December 27, 2010 6:48 PM  
Blogger Dan said...

Hey dh, just want to say thanks for this and all other posts. It's been such a wonderful resource to help me get acquainted with the vastness of photo-related information out there. Happy new year to you and your family. This post was particularly inspiring, and here's the result!

December 30, 2010 12:29 PM  
Blogger Willem de Vlaming said...

First of All
Happy New Year

This is my first post, but I´ve been browsing your blog for a little while. I´m just starting to find my way using my one and only off camera strobe. Sometimes in combination with the pop up.

Your blog isn´t just very good information, but also a great inspiration for experimenting.


Willem de Vlaming

January 03, 2011 3:46 AM  
Blogger Ian Pack said...

I've posted a couple of shots on my blog showing the effect of Rosco ToughPlus Green gelled flash on a dull grey English sky I would have liked a decent sunset, but hey, this is England, the land of liquid sunshine.

January 07, 2011 5:46 AM  

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