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Archive 2012 · WB & CTO
  
 
esanchez
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p.1 #1 · WB & CTO


What WB should I use when using 1/2 CTO or CTO Gels? If I use 3200 the CTO will be balanced correctly. So I should I use Flash WB or what WB can be used to get the warming effect?


Jul 23, 2012 at 03:56 AM
brett maxwell
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p.1 #2 · WB & CTO


Whatever looks good to you. I use 1/2 and full CTS (very similar to CTO, just a little less red) a lot for wedding receptions and I like a warm look to the photos, so I'm usually at 4500-5000K with 1/2 and 3300-3800 with full.


Jul 23, 2012 at 04:07 AM
cgardner
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p.1 #3 · WB & CTO


Depends on what your goals are for the balance of the flash and ambient.

I gel my flash with 1/2 CTO when shooting in tungsten ambient light. My primary goal is normal WB on the flash lit faces in the foreground and avoiding the unnatural looking orange background I'd get if using ungelled flash with Flash WB.

Since I want "normal" (i.e. neutral) WB on the faces I put 1/2 CTO gels on my flashes then set WB off a gray card using the gelled flash.







That ensures that any face in the flash lit foreground the more important ones look normal. The 1/2 CTO may not be an exact match to the background tungsten color temp because that varies so much. I find that rendering the background on the warm side, versus an exact match to the flash, creates ambience in the photo that matches my adaptive vision in person. That's why I use 1/2 CTO vs full CTO which would create a closer match.

In the shot below the key and rim lighting is the tungsten stage lighting. The stage fill in the shadows had a heavy magenta cast so I used 1/2 CTO gelled flash on my bracket from the shadow side to overpower and eliminate it. You can still see hints of it in the shadows the flash didn't reach:







Same stage, different situation. The lighting was set-up flat and rather bland for a teen talent show so I decided to put my OCF on stage to the left to create some 3D rim lighting the stage lighting lacked, using frontal fill from my flash on bracket. Gelling the flash with 1/2 CTO allowed it to blend more seamlessly with the stage spots and lighting on the people further back lit only by the ambient.













So the goal of the exercise in using the gels for me is to balance the flash temp to the ambient temp with the gels to eliminate the mixed lighting problem. Since I'm intentionally not going for an exact match, using 1/2 vs Full CTO simply setting the camera to Tungsten WB wouldn't give me neutral WB on flash lit faces, which is why I take the 30 sec. it takes to set Custom WB.

It's also important to note that while I set Custom WB to the gray card for consistent predictable WB at capture I may adjust the faces off that neutral baseline in PP. But shooting RAW with consistent WB at capture allows me to correct the first file to taste, then copy / paste that adjustment into the other RAW files. In most cases I don't find I need to adjust the WB when using that workflow.

FWIW - Something to be aware of if a Canon shooter using Canon flash is that the flash sends WB information to the flash in AWB and Flash WB modes. As the power of the flash changes the it's WB shifts. That introduces a variable you can't monitor or control. That auto adjustment isn't in play when other presets or Custom WB is used.



Jul 23, 2012 at 03:27 PM
BrianO
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p.1 #4 · WB & CTO


esanchez wrote:
What WB should I use when using 1/2 CTO or CTO Gels? ...should I use Flash WB or what WB can be used to get the warming effect?


If you set "Flash" white balance, the camera will adjust the colors so that a bare flash -- which is normally somewhat bluish -- will look neutral. If you then add a warming filter to the light, but leave the WB set to "Flash," the resulting image will be warmed by the amount of the gel -- either 1/2 or full in your example.

If you change the WB setting, it will change the amount of warming. You'll have to experiment to find what other settings you may like or dislike.



Jul 24, 2012 at 06:55 AM
 

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unknown_photog
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p.1 #5 · WB & CTO


Correction gels are mainly used to balance out the flash temperature with the ambient temperature. But you can also use them to change the ambient and control the flash.

The white balance setting on your camera will depend on the effect that you want to do.

If you are playing with kelvins a good tip to keep in mind is:

Warm it up and Cool it down. Raise your kelvins to warm the image, lower the kelvins to cool the image.

At a kelvin of 3200 the CTO is corrected because when you lower your kelvin you are telling your camera that you are shooting in very yellow light so it adds blue to correct it, hence neutralizing your gel.

If you want the gel to be exactly as you see it you can put the camera on daylight, or 5500k. This will tell the camera not to correct the WB and will show you the true effects of the gel. When you set your WB to flash, you are telling your camera that you are shooting in a little bluer light, so the WB in your camera will actually add yellow to compensate. So if you have a CTO on your flash and you set your WB to flash it will be "warmer" than the CTO gel is.

Hopefully that makes sense. Just remember that the WB on your camera is actually a correction and it's opposite of the true color temperature of light. So when you are adjusting your cameras WB you should be thinking backwards.

For example, a candle is very yellow light, in reality the kelvin temperature of the candle is around 2800 kelvin. But in your camera if you where to set it to 2800 kelvin and you aren't shooting in candle light, then the photo would look blue. This is because the WB is actually a correction and adds the opposite color of what you are shooting in to correct the whites.

Andy



Jul 24, 2012 at 07:04 AM
esanchez
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p.1 #6 · WB & CTO


Thanks Andy makes total sense now. Never thought about it that way.


Jul 29, 2012 at 05:35 PM
unknown_photog
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p.1 #7 · WB & CTO


@esanchez, glad it helped!!


Jul 29, 2012 at 05:45 PM





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