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Quick, what’s the difference between the light from your flash, the sun, those crazy, twisted light bulbs and the not so crazy twisted light bulbs? Easy answer: degrees Kelvin, or the color the lights give off. Not all light is equal and those who have done any amount of photography know how radically different light sources can be. Even the sun light coming to the Earth’s atmosphere changes temperature as measured in degrees Kelvin as the Earth rotates. This became glaringly apparent when color film came on the scene. Special films were made to match the color range of certain lights. Then came digital and its ability to magically switch between light color temperatures on the fly.
As handy as the digital revolution has been for color balancing, it still can’t make much of an impact when a flash is used in conjunction another temperature of light, like incandescent indoor lights. We’ve all seen the photos with a slight blue-white color cast on a face and the scene behind is a sickly orange-yellow. Or the green light given off by florescent lights. So what are we to do to make our camera happy with the color balance selection?
The simple answer is color gels. Specifically, color gels that approximate the color temperature of specific light sources. There are a number of sources on the internet where these gels can be purchased and the easiest kits I’ve found come from Photogels.com. Complete with color correction gels as well as special effects gels, and enough velcro to attach them to a standard flash, I purchased a three pack to cover all my flashes. There are three shades of each color correction gel to help match the temperature of ambient light (NOTE: You can put velcro on both sides of the gels and stack them to further fine tune the correction) and the kit comes with gels for matching sunlight (blue in the picture above), incandescent(orange) and florescent(green).
In practice the use of gels is simple. Just add and remove to your flash as you see fit. The gels can even be stored on the flash, out of the way, when not in use. To give you a better idea of how gels can affect light, I tested them out in a few different configurations when using the orange gels for incandescent (indoor) light.
First, let’s start with a baseline picture. (Thanks to my daughter for unknowingly donating some of her travel gifts)
(50mm, 1 second, f/11, ISO 100) I took a custom white balance for the overhead incandescent lights. As the lights are directly overhead and this setup is shot on a counter, heavy shadows are cast and you can’t even see the Statue Of Liberty’s face. So let’s use the flash to fill in what’s missing.
(50mm, 1/2 second, f/11, ISO 100) Yikes!! With the same white balance as before, the flash is killing this picture. The shutter is longer to get better depth of field with the closeness of the subject matter. Well then, let’s change the white balance to flash and get rid of the blue cast.
(50mm, 1/2 second, f/11, ISO 100) Getting a little closer with the white balance now set to the flash temperature. The depth of field is still causing the shutter to remain open for half a second. This allows the overhead lights to cast their (now ugly) orange light on the scene. Hmmmm, what if we cut the shutter speed down to get rid of that overhead cast?
(50mm, 1/250 second, f/4, ISO 100) Increasing the shutter speed cut down on the orange cast, but the depth of field is horrible. It’s time to try out the gels on the flash. First we’ll use the lightest gel and work our way up. For reference sake, let’s call the lightest gel a +1, then +2 for medium and +3 for the darkest gel.
(50mm, 1/2 second, f/11, ISO 100) We’re back to the custom white balance for the overhead lights. The flash is firing but now there is a +1 gel on the flash. Comparing this to the second photo above (no gel, but custom white balanced the same and flash firing) there isn’t a ton of difference. Let’s take off the +1 and try +2.
(50mm, 1/2 second, f/11, ISO 100) With a +2 filter and custom white balance, we’re getting a little less blue cast from the flash, but need to keep going.
(50mm, 1/2 second, f/11, ISO 100) +3 now and the color, while not popping out (truth be know, the overall white balance could be adjusted slightly, but incandescent bulbs aren’t always known for their wonderful color renditions) is noticeably less blue cast from the flash. Let’s combine the +3 with the +1 for a +4.
(50mm, 1/2 second, f/11, ISO 100) We’re at +4 and, on my screen, the background is starting to become a tad orange from the power of the flash. But not horribly so.
(50mm, 1/2 second, f/11, ISO 100) Now for +5 (the darkest gel combined with the medium gel). The background is indeed getting orange cast and the duck is looking even more sickly. No one likes a sickly duck. Or llama.
(50mm, 1/2 second, f/11, ISO 100) And now for +6, all the gels combined. By this time it’s too much, but there are cases when you may need to use all three gels.
While this demonstration is a bit simplistic, I hope it helps you understand how flash gels can be used to balance out ambient light. While there are other adjustments that can be made (such as increasing the flash output when more gels are applied as I don’t feel the E-TTL compensated enough), it serves to show how just the color can be balance. The other colored gels work the same for outdoor light and fluorescent light. Just note that you can’t use multiple colors at one time to balance out multiple light temperatures.
May 12, 2012 07:26 pm
Those gels are pretty handsome for some wedding situations, especially when shooting on cloudy day.
Before mastering the gel techniques it took me several months to perform some nice shots.
Don't ever shoot in JPEG if you want to reajust color balance in post product.
March 23, 2012 05:53 pm
Does this guy really think that shutter speed affects depth of field? Or was he trying to say that closing down the aperture to get the desired depth of field required a longer shutter speed?
June 18, 2010 04:38 am
@John no it wouldn't help because it would be like you have a yellow ball and a blue ball and trying to make them be the same color. Image #3 should have the color metered to what is believed to be correct.
June 18, 2010 01:44 am
Perhaps I don't understand this totally but it seems like this could be accomplished doing a custom white balance with either a gray card or something like an expodisc. Woudn't either of those items help with multiple light sources?
June 15, 2010 01:13 am
I find a great combo a Lumiquest FXtra together with Rosco Strobist kit.
June 14, 2010 02:51 am
I've been playing with color gels quite a bit since I got a set of three (by Lee Filters) for free from a photography magazine (I think it was Digital Photo). Here are three sample shots of mine with the three different gels I have:
Overall, I find the warming filter to be most useful.
June 13, 2010 01:26 pm
Admittedly, I would like to know what the photographer needs to do to get the final image to have the same colors as 3 and 4. Actually 3 really wasn't all that bad.
I finally realized that of course it needs a little bit of photoshopping. So I took the last image into photoshop, I forgot how to do a white balance on photoshop, so I just slid the magenta down till the magenta hue wasn't visible to my eyes. Then I did a much needed brightening of the image. I then upped the contrast to try to make it appear to have the same color as the image with just the flash. I hope I got it close. But that finally puts me at ease, that the job was accomplished, and you get the result that was intended.
[eimg link='http://www.flickr.com/photos/stevehurl88/4695167294/' title='final' url='http://farm5.static.flickr.com/4002/4695167294_9d833938b7.jpg']
June 13, 2010 12:47 pm
@Ludwig if the shutter wasn't open for half a second, there wouldn't be a problem needing solving. He notes the flash wasn't strong enough by saying "While there are other adjustments that can be made (such as increasing the flash output when more gels are applied as I don’t feel the E-TTL compensated enough)"
Of course that more explains why the image is a bit dark, with all three gels added to it. I'm not lucky enough to own my speedlights, but I think the solution to that problem would be setting the flash exposure compensation up a bracket? I do this sometimes when I'm bouncing light off the ceiling or wall. Using strobes though, you don't get the metering, so you can only control your flash's output.
Anyway, points aside on how to fix the flash issue, there needed to be a problem for there to be an article explaining the fix. As we saw in the image where it was taken at 1/250th, there wasn't ambient light showing up.
In a similar example of fixing the ambient light and flash to be on the same color temperature, a friend of mine was photographing a basketball game inside a poorly lit gym. I believe he used like 800 ISO, and I forget what the shutter speed was, but he was getting both ambient and flash to light the scene, and he used gels to keep the color the same. It's a very practical solution.
June 12, 2010 08:09 am
"The depth of field is still causing the shutter to remain open for half a second." ...? WTF?
You know you can just set the the shutter speed to 1/200s, set your aperture to f11 and increase the flash output, right?
I liked the introduction about the gels and vecro-ing them to your flash very much, however :) Your writing is very pleasant to read.
PS: One might have included a link to David Hobby's spin on the topic:
June 12, 2010 07:14 am
I find this article pretty helpful. I've heard of balancing the color before, I haven't done it before, but I'm glad that now I know how. Aside from picture four, it was underexposed, probably because of the gels. But I think that's missing the point.
For those that haven't ever balanced the flash color with the ambient color, they should now know how to. Having the author get the perfect shot doesn't really matter, rather that now the readers have an idea of how to work towards getting that perfect shot. In my experience, I've just tried to over power the ambient light. I tend to end up with little tiny spots of yellow light. If I get my hands on gels, maybe I can fix that now.
June 12, 2010 05:18 am
Gels are not really just for fixing the white balance, you can do that in camera of on your computer, it's for matching your flash to the ambient light so the whole image can be evenly white balanced.
June 12, 2010 05:18 am
Dave, I'm not sure I understand your comment. First, these were shot in RAW. Second, take a look at the third photo as it has light at about 5000K and 3600K. You have to pick one white balance in that case, so which one (that photo is set to 5000K for reference). That is one of the problems when using a flash with ambient light. There are other tricks to get around the two light temperatures, but this post is just showing one of them using flash gels. Joe has some other excellent ideas and does great work.
June 12, 2010 05:14 am
heatergu, while that does work to some extent, it's still a compromise because the difference in color temperature, in degrees Kelvin, could be around 1000K. Using the gels brings the flash in range with the other light and thus not requiring a compromise. Or a sync cord. :)
June 12, 2010 05:11 am
Hi Jason - The 'perfect' shot would have been further enhanced in post processing, since this lighting situation is not a fancy studio setup. It was meant to show the range of color balance that can be achieved and for some people, it could be one of a couple of those images above. I chose not to perfectify (it's a new word :) ) the image, but just present real world results most of us can expect.
June 12, 2010 05:07 am
When shooting RAW white balance is not an issue if all the lights are the same color. But if you have florescent light and flash you might want to consider using gels. Other wise if you color balance for flash your background will be very orange or green, while if you color balance for florescent your foreground will be blue.
Other wise if you do use gels to correct the colors to each other, even if you do set the color balance wrong and shoot in RAW you will later be able to correct to the correct white balance.
June 12, 2010 04:58 am
When faced with this situation I do a custom white balance shooting the flash into the lens under the tungsten lights with great results. Of course, you will need an flash extension cord to accomplish this.
June 12, 2010 04:20 am
Generally, white balance is not an issue when shooting RAW if you have only one color to correct.
But if you have ambient light (e.g. in tungsten or fluorescent) and flash light with similar strength, you have two colors to correct. The shadows of the ambient light are filled by (blueish) flash light, and the shadows of the flash are filled by ambient light (orange-ish or green-ish). Try correcting that in post-processing is really difficult, especially if you have a whole series of photos to do!
By gelling your flash, you make the color of your flash match the color of the ambient light. Which leaves you with a single color to correct, which is simple when shooting RAW (or setting your white balance of your camera).
June 12, 2010 03:34 am
>>>White balance in general is not an issue when shooting RAW which anyone serious should be doing.<<<
"Anyone serious"-haha, says who? Dave, have you ever shot in a tungsten environment with your flash? The use of gels is the only way to get rid of the color cast! (If you don´t want to spent hours in photoshop messing around with brushes and masks).
June 12, 2010 03:14 am
I was expecting after scrolling all the way down to see the final, perfect shot. Hmm.
June 12, 2010 01:17 am
Interesting article--very useful. I have experimented with gels in still photography, but now I'll have to try some more ideas.
One small quibble: "Kelvin refers to a unit of measurement, not a scale. Light (like temperature) is measured in "Kelvins." There is no such thing as "degrees Kelvin."
June 12, 2010 01:14 am
White balance in general is not an issue when shooting RAW which anyone serious should be doing.
The thing that Joe McNally goes on about gels for is balancing colour - warming up the flash for indoor use and so on.
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