Gelling the flash to balance for other light temps - how?

Hi,

I often have to take pictures in circumstances where I need to balance flash with other light sources. So far I've never tried to compensate for this, but I am starting to see I need to do this now. I have a set of gels (actually two sets), but now I am trying to understand how to use them.

Can anyone point me to a tutorial to help me understand this better?

Specific questions would be:

• On this forum I see terms like CTO. But my Nikon flash-gels have names like 'TN-A1' and 'FL-G1'. What is what?

• How do I know which gel to use? I imagine I have to set the camera to the temperature of the existing light, and then gel my flash appropriately to match that?

• I do have a grey-card. It's a few years and mainly sits in my camera-bag. From what I've read on this forum I get the impression that such a card can suffer from discolouration and no longer be accurate. Is that true? The card seems pretty grey to me still. How much can the deviation be?

• When I am in circumstances where there is tungsten and fluorescent at the same time, which do I try to match?
• Are spot lights in theaters and clubs usually tungsten?

Thanks for any help you might be able to offer!

Rogier

--
Rogier Bos
Rotterdam, The Netherlands
Digital communication and imaging
web: http://www.rogierbos.com/
photoblog: http://ourjourney.typepad.com/photo/

get this
http://www.rosco.com/includes/technotes/filters/FilterFacts_06.pdf

Lee Filters may have something similar

RogierBos said:

• On this forum I see terms like CTO. But my Nikon flash-gels have
names like 'TN-A1' and 'FL-G1'. What is what?

Click to expand...

that's just Nikon's product number... look at the color
TN-A1 are roughly CTO... dunno what stop though
FL-G1 are roughtly plusgreen, not sure what the stop is either

--

We have art that we do not die of the truth.
--Friedrich Nietzsche

spots in theatres/clubs will be tungsten (unless gelled). With tungsten and flourescent then gel to the dominant. You can always shoot a few frames with daylight white balance to find out what the colour looks like. It will probably vary from area to area. Depending on what you are doing then you might want to get rid of the ambient light to get away from the mixed lighting issue. Its not always possible to balance to mixed lighting and get anything useable.
----
http://www.dazedproductions.co.uk

Are there rules of thumb for when to use 1/8 CTO vs 1/4, 1/2, etc.? That is something that I have never quite figured out other than playing around and hoping for the best.

That's exactly how its done, you experiment on site. Over time you'll develope a feel for the amount to use in any given situation but ultimately you just experiment and make adjustments on site.

One of my favorite quotes ever comes from Joe McNally. He mentions always using the "WAG" method in sorting out lighting....Wild A** Guess.
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BigPixel / Hawaii

that is some ugly light

Only if I"m using a flash for fill, and the fluorescent is the major light. I try to use my strobes for light, and over power, or avoid using fluorescent.

Putting gels on flashes is always a guess because the different tungsten light sources are rarely the same color temp. You will almost always end up with some color casts. In most instances, all you can do is, as mentioned, gel to try to match the dominant tungsten source. And always shoot RAW.

Probably the easiest is to kill the ambient light with a high shutterspeed.

Fastest flash sync is usually around 1/250 sec depending on the camera.

Obviously you may not be able to do this depending on the subject, in which case you will have to resort to gels.
--
Phil_L

--thank you

http://en.wikipedia.org/wiki/Color_correction

--

We have art that we do not die of the truth.
--Friedrich Nietzsche

Welcome to the wonderful world of flash photography. I am kind of a newcomer also and I urge you to visit strobist.com - it's got tons of info, examples and tutorials about small flash photography.

Also, check out authors like Joe McNally (big PJ pro, shoots Nikon and uses mainly Nikon speedlights in his photos.

Cheers,
Nuno B.

An 81 get will balance your flash to tungsten light. Gel your flash and set your camera to tungsten WB. The gel will cut the output of the flash somewhat (1-1/3 stops if my memory is working correctly).

Flourescent lights are much trickier, depending what kind of bulbs you are dealing with. Even will vary with the manufacturer.
--
unc

~ The only things stopping us from reaching our goals are the limitations we place on ourselves ~

http://strobist.blogspot.com/2006/03/lighting-101-using-gels-to-correct.html

My 2 cents:

You should indeed gel your flash according to the light source and camera WB, e.g. tungsten = CTO - Color Temperature Orange.

When you have different kinds of lights, e.g. fluroescent+tungsten, you should capitalize on one of them and try to supress the other.. those situations are usualy a nightmare for correctly white balancing.

Your grey card is always a good bet in tough situations, although in my little experience I can say that you must be very careful, for example if your subject moves a little closer to a given light source than before and moves away from another, or if your shooting angle/distance-to-subject varies, etc.. In those situations I think one should take new and frequent readings from the card.

Hope this helped.

Cheers!
Nuno B.

Thanks for all the responses so far. I've looked at the referenced links and sorted through my gels. Got my CTO and my FL (Window) green to compensate for Tungsten and Fluorescent.

Which brings up a new question: if flash is 5400K, direct sunlight is 5200K, shade is 8000K and a cloudy day is 6000K, do I compensate the flash with gels for those situations?

It seems to me that direct sunlight and flash are close enough (are they?), but I should compensate the flash for shade and clouds. But with what colour?

Appreciate your help!
Rogier

--
Rogier Bos
Rotterdam, The Netherlands
Digital communication and imaging
web: http://www.rogierbos.com/
photoblog: http://ourjourney.typepad.com/photo/

RogierBos said:

Which brings up a new question: if flash is 5400K, direct sunlight is
5200K, shade is 8000K and a cloudy day is 6000K, do I compensate the
flash with gels for those situations?

It seems to me that direct sunlight and flash are close enough (are
they?)

Click to expand...

Yes, I guess you can say that, because the flash light is meant to be 'white', just like daylight.

RogierBos said:

, but I should compensate the flash for shade and clouds. But
with what colour?

Click to expand...

If the ambient is much 'hotter' than the flash light, if un-gelled, its light will cool out your subject so, if you don't want that, you'll need to balance it all again with CTO (1 or 1/2 or maybe just 1/4 - you should try every gel until you are satisfied).

good answers here; gels & wb setting brings you in the ballpark. i might add that however mixed the light is shoot your grey card (or any white/grey surface) - positioned as your subject will be - and just use the custom wb on your dslr. Another way is to start the shoot with the grey card included in the scene (just the 1st shot) and then in pp you will always have a reference point. if the conditions change do it again... hth, sz

Situation: Taking pictures in an indoor arena with florescent lighting

Question:

If you use an Expodisc to set the custom white balance in your camera because the environment you’re taking the picture in creates a color cast AND you plan on using a flash, do you still need to use a flash gel to compensate for the color cast the flash will detect?

Correcting flash for ambient light can be challenging, but I've had really good results from a product I discovered call sticky filters. I use them nearly every day for my newspaper assignments. Check out stickyfilters.com
The inventor, Kent, is a cool guy. Tell 'em Rex refered you.

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BigPixel / Hawaii

Objection, your Honor!

With most cameras the use of the Expodisc, if done properly, will indeed set the WB of the "bad" light right. However if you then add flash to the shoot the light emitted by the flash unit, when it hits the sensor, will of course be subject to the same amount of "correction" that has been manually set, with the result that the colours of whatever in the scene happens to be illuminated by the flash will turn out to be wrong!

There are a very few cameras around that can custom set the WB when a flash is fired. The Sony 828 for example, a model that unfortunately has no comparable successor currently made, is one of these and if you happen to be able to use such a not too popular tool the issue becomes a non-problem in a flash (pun intended!)

Been there, done that..... in fact doing it almost daily, as you might have properly deduced I am the happy owner of an 828.

Kind regards,

Johannes