Lighting 102: Assignment | Work That CTO

We've talked about the primary use for the CTO warming gel -- balancing strobe, which is (close to) daylight balanced to the color of incandescent light. In a tungsten room you CTO your flash, set your WB to incandescent, and Bob's your uncle.

But the CTO is such a useful, sweet little gel to have around, we can't stop there...

CTO Overdrive

Pictured above is Shadi, whose stunning good looks proved to be such a distraction to the ladies in the Dubai intermediate class that we had to move outside to disguise the fact that he was clearly making them all hot under the collar.

And hot it was. Dubai is about 172 degrees in the shade in the afternoon. But they make up for it by sucking all of the color out of the sky for your photographing pleasure. To call this sky a hazy grey is to do grey a disservice.

But that didn't stop us from getting a rich-blue, ad-hoc portrait of Shadi in the courtyard. We had to be quick -- people typically start to burst into flames after about five minutes outdoors in the afternoon there. So to get this shot of Shadi, we walked three SB-800s out, already on stands, and set him up in a triangle configuration.

We essentially dialed in the blue background by shifting the camera's white balance to incandescent, even though we were shooting in a daylight environment. The white balance "fixes" tungsten light by throwing a lot of blue in there. Hence our newfound color.

The back flashes were with no gel. We let them push a little bluish rim light to accentuate the sinewy muscles that define Shadi's neck. Ladies, you may wish to sit down and/or grab a glass of water at this point.

But take a look at that area, because that's what an ungelled flash gives you on a tungsten/incandescent WB setting. You can see the photo bigger in a new window here.

To light Shadi's face, we had to get the light from that flash to be appropriate in our new, tungsten WB setting. So we warmed it up with our CTO, turning it into the "correct" light for this setting. In effect, one little orange piece of acetate turned this whole environment blue.

Well, two pieces, actually, as I added another 1/2 CTO to bring the flash beyond "correct" and have it warm-light Shadi's face against the blue. This is a neat trick to whip out on a crappy day (or at twilight on a no-show sunset) when you need some atmosphere. I have used it for food shots and moody portraits alike.

You may also notice that we are underexposing the ambient by a couple of stops to get a good, rich color. It is not enough just to shift it -- you have to knock it down, too. We could have easily warmed up the rim lights, but I like the steely effect of that blue rim. Especially for a man who just oozes confidence as does Shadi.

You can do it indoors, too, with the daylight streaming through a window.

I faved this photo a ways back, 'cause I just loved it. Turned out it was shot in Dubai by none other than Sid Siva, (AKA Sid the WonderVAL) who I would be shooting with out in the UAE desert only weeks later. Small world, huh?

Sid used the exact same color shift technique on this biz portrait in Dubai. Set the camera to incandescent. Crank the exposure until it looks rich, and throw some CTO-gelled flash in where it counts.

Sid for the win.

You're Getting Warmer... Warmer...

So the CTO (plus another 1/2 CTO) thing is a staple for me when I need to drop back and punt on a colorless day. But I have been seeing some stuff come upstream from you guys which is making me wanna use my CTOs even more.

Check out this climbing photo, by Dr. Benny. This photo rocks. Just pushed a little CTO up in to there with the camera set on daylight. The CTO gives you the familiar warm of a tungsten bulb -- or that last hint of golden light at the end of the day when it gets really red.

That splash of light just totally makes the photo. Just a little beam of last-minute sun coming through a hole in the unseen rocks. Only not quite, you see as you take a second look. Because the daylight is coming from up top. The crosslight thing he has going on is totally sweet.

Think light balancing for a second while looking at this photo. What makes it sing is where The Doctor chose to expose the ambient light before adding in the CTO splash. He could expose for the highlights, let the rocks go darkish, and build that CTO right up in there.


And this photo, voted by me as the "Photo I am Most Likely to Rip Off" of the month. Mazzapix mixed some CTO light (through a straw grid) with some straight light from another flash in a daylight WB shot, and made a quick test for a headshot look like a movie poster.

That is what I am talking about.

You may sense that I get just a wee bit excited when I start talking about gels. And why shouldn't I? All of these photos were made with the help of a tiny little piece of orange acetate. And the samples are free. How can you not like that?

Your Turn

We have not done an assignment on L102 in a while, so it is time to break out the cameras.

This time, you'll be using a CTO gel in one of the two ways described above -- both technically "rule breakers," if you will. You'll either be doing the tungsten WB shift thing in a daylight environment, or throwing some CTO into a daylight WB setting in a daylight environment.

The subject matter is open, meaning that some of you will namby-pamby your way through it with a teddy bear, or a mannequin or an egg (please, oh please, not an egg.) But others will use this as an excuse to stretch. And you know I live for stretches.

Here's the Deal

For this assignment, your tags will be:

Lighting102 (note, no spaces)
WorkThatCTO (no spaces)

You can see all of the photos from this assignment here. Discussion for the assignment is here.

The assignment is due at the end of the day on June 24th.


Related Posts:

:: On Assignment: Spring Desserts ::
:: On Assignment: Man in a Boat ::

NEXT: Discussion - CTO Assignment


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Anonymous Anonymous said...

Discussion for the assignment link doesn't work.

June 03, 2008 1:15 AM  
Blogger Nald said...

i'll be joining this assignment. also, i now noticed how important avoiding Auto in WB. I've been RAWs but I now realized that CTO'ed flash & Auto WB is not an optimal combo.

June 03, 2008 1:17 AM  
Anonymous ncwalker1 said...

As always a brilliant post, only this time extra special having been on location with you for the shot (with a G9 in high speed sync).

I'm surprised Shadi hasn't made comment yet!

June 03, 2008 1:25 AM  
Anonymous Ramstech said...

Gremlin crept in.
That second url should be edited
with ' removed'

Links to discussion for this assignment.

June 03, 2008 1:37 AM  
Anonymous Scott Regan said...

Hahaha "this photo ROCKS" - get it?

they're climbing rocks?

I guess I just find subtle puns funny...

June 03, 2008 2:56 AM  
Anonymous Davidoff said...

I'm glad the 102 is back on track! Just wanted to point out there is an error in the link to the discussion thread. Regards!

June 03, 2008 3:12 AM  
Anonymous wedding photographer france said...

Could you have overpowered the Dubai sky without your G9. You were talking about high-speed sync, so I suppose you were working at 1/1000 sec or something like that.

On a classic dSLR rig and our limit of 1/200 or 1/250 of a sec could we still have accomplished this shot without having to close the aperture incredibly and therefore use even more flashes?

June 03, 2008 3:40 AM  
Blogger Emmett Photography said...

The link to the Flicker discussion thread is incorrect - "You can see all of the photos from this assignment here. Discussion for the assignment is here."

It currently links to

and should like to


June 03, 2008 4:19 AM  
Anonymous matt burns said...

In the paragraph starting "To light Shadi's face..." you meant "with our CTO" not "with out CTO".
I'm sure most people would work that out, but a noob like me needs to think about it a bit to be sure ;)

ps. I read these blogs at work and it's really annoying because I want my camera and I want to start playing NOW!


June 03, 2008 5:31 AM  
Blogger David said...

Thanks for the link check! (Fixed)

June 03, 2008 7:38 AM  
Blogger Dave said...

You realize you are practically begging for a slew of egg shots, right??

June 03, 2008 9:57 AM  
Blogger Shadi said...

i just want to say I'm available for hire if anyone wants to replicate the shot above... i'm dumping photography for a pro modeling career (huh!) thanks to Mr. strobist himself.

not sure if it's only me, but being featured on feels pretty darn close to being knighted !


June 03, 2008 11:51 AM  
Anonymous Mason Trullinger said...

CTO gels come in several strengths (1/8, 1/4, 1/2, 3/4 and Full) which all correlate to different specific white balance temperatures. The white balance temperature for the incandescent/tungsten pre-set on most cameras is 3200K. So to use that pre-set and to get correct looking skin tones lit by a CTO'd flash, you'll want to use a 3/4 CTO gel which will shift your 5500K daylight balanced flash to 3200K. You can always stack a 1/2 CTO and a 1/4 CTO to reach this 3200K mark if you don't have a true 3/4 CTO gel in your bag.

The real power of using CTO (and CTB) gels is knowing the correct temperature they shift 5500K to and forcing your camera to use that specific white balance temp. Using the different intensities of CTO gels will allow you to control how deep of a blue you background will be at. The higher the CTO gel on your flash, the deeper the blue will be in your backgrounds.

Here is a chart outlining the different gels and the corresponding white balance temperatures you will need to dial into your camera or RAW processor:

Full CTO - converts 5500K to 2900K
3/4 CTO - converts 5500K to 3200K
1/2 CTO - converts 5500K to 3800K
1/4 CTO - converts 5500K to 4500K

On the other direction of the white balance scale, CTB gels are useful if you are shooting outdoors on an overcast day. The clouds shift sunlight to the blue end of the spectrum so you use a CTB gel to match the light in overcast situations. Of you can use CTB gels in normal daylight to shift the background to orange.

Full CTB - converts 5500K to 7800K
1/2 CTB - converts 5500K to 6400K
1/4 CTB - converts 5500K to 5800K

Mason Trullinger

June 03, 2008 12:06 PM  
Blogger lbattist said...

I have done this quite a bit too myself. Another thing to try is to use a green gel. This will make daylight become pink/magenta-ish.

June 03, 2008 1:03 PM  
Blogger BurroJoe said...

Thanks for the help.

I used my CTO recently:

June 03, 2008 1:52 PM  
Anonymous Max Surikov said...

Great info. I attended a training seminar yesterday lead by Bob Davis (Bob was Eva Langoria wedding photographer)
During the training he "blew everyone's mind" with his gel setups, mixinig and matching the various light sources and a variety flash props in a similar fashion to what was demonstrated in the post.



June 03, 2008 2:50 PM  
Anonymous Anonymous said...

i like the tungsten WB double CTO technique in daylight environment but since it is an obviously "created" look, also has the tendency to get old very quickly. i like it but find it overpowering the image at times. i mean the lighting part takes front seat to the image itself. i am also into cool techniques like that but often find myself going for a technique because it looks good regardless of content. tough to find the right balance there.

with the tungsten wb double cto combo in daylight environment i find the "yellowish/orange" face sometimes a bit of a "sickly" problem.

however, it really highlights how opposite colors used in combination do make the image pop.

thanks for your hard work dh.


June 03, 2008 7:03 PM  
Blogger Oliver Thomas said...

Oh man, thank you for this. I went to town on the idea, and am pretty sure ended up with the coolest photo I've ever taken of a cat.

Keep Strobing!

June 03, 2008 7:43 PM  
Blogger Eric said...

This is not an assignment entry, but I saw this photo and immediately thought of your post.

This girl is so wonderfully talented.

June 03, 2008 9:04 PM  
Blogger Dan said...

I'm new at this -- do I just need to upload and tag the photo, or do I also need to send it to the group?

June 03, 2008 10:56 PM  
Blogger Siddharth said...

and i was wondering why there were so many people visiting my flickr yesterday! lol! nice post David..

June 04, 2008 12:11 AM  
Anonymous ShaolinTiger said...

Heh funny, the shoot I did last weekend I was playing around with a CTO on my SB-800 through a white brolly to get a cooler bg. Worked out quite well. Here's one from the set:


June 04, 2008 4:13 AM  
Anonymous Jason said...

Thanks for the CTO scale...I also noticed in my Roscolux pack that they are numbered and also have a 1/8 CTO, so to add to the CTO scales:

3407: Full CTO - converts 5500K to 2900K
3411: 3/4 CTO - converts 5500K to 3200K
3408: 1/2 CTO - converts 5500K to 3800K
3409: 1/4 CTO - converts 5500K to 4500K
3410: 1/8 CTO - converts 5500K to 4900K

June 04, 2008 3:57 PM  
Blogger Bigpixel Photography said...

Great assignment. I don't have any CTO gels yet but they will be on the way. Thank you for all your great info, as always.

June 04, 2008 11:19 PM  
Blogger Damian said...

The advice for using camera white-balance to change a grey sky blue, then compensate with a gelled flash was like an epiphany for me. Can't wait to try it out, and no longer need fear cloud cover.

June 05, 2008 8:28 PM  
Blogger said...

Just shot Ivanka Trump with a cityscape background and a 1/2 CTO on my off camera SB-800. Not a great pic, but the result is still nice. I actually use this method with my wb set between 3100-3300 K, depending on the environment for everything I shoot.

Awesome assignment!

June 05, 2008 10:58 PM  
Blogger LuminonPhotography said...

This will be my first foray into participation but I am SO in!

June 08, 2008 8:39 PM  
Anonymous Scott A. Schowalter said...

I've been playing catch-up for about 6 months, but now I can finally make a deadline. I've been playing with this technique ever since the "How to photograph Christmas lights" post.

Thanks, David, for such an awesome resource!

June 09, 2008 2:22 PM  
Anonymous Rinkrat said...

I just read Lighting101 but then cheated and jumped ahead to the current subject after buying some remote flashes. I tried this technique using wifey as the victim and she loved the results. It's her new avatar. ;)

Took the pics at 12 noon under grey skies and it looks like she is in Hawaii under a deep blue sky.

Love this blog!!

June 09, 2008 9:33 PM  
Blogger LuminonPhotography said...

O.K. The photos have been taken. The assignments are in. All of us avid Jr. Strobists wait oh so patiently (or not! LOL!)

June 26, 2008 12:20 PM  

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