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How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)
  
 
Bartlett Pair
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p.1 #1 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


I started gelling for tungsten to combat incandescent recently. However, I've found myself blindly always using 1/2 CTO by default. Sometime the light seems a little 'muddy,' which leads me to believe there is a color difference between the gel/ambient. Is there a best/fast technique to determine which gel strength to use? We do mostly weddings, so we need to quickly figure out the ambient color of a church etc.

Also, if I'm bouncing gelled flash off of something like a wood/beige ceiling, how should I adjust? Or what if the ceiling is blue, etc?



Sep 05, 2013 at 04:31 PM
Turbohamster
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p.1 #2 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


The only way to really tell exactly what colour temp the ambient light is to shoot a grey card using the ambient light.

You could then match your gels to the white balance reading as close as you can. Although I think thats really a bit of overkill for events.

Easiest way for me is to take a few pics with 1/2 cto gel and then look @ the ambient light in the shot, if it appears more orange than your subject lit by your flash, then you need to step up to 3/4 cto. If the ambient is more blue then you need to step down to 1/4 cto and so on.

If the ceiling is a weird colour you are probably better off setting up flashes on light stands in the corners of the room or using direct flash.

But as ever experimentation is key



Sep 05, 2013 at 04:55 PM
irish-george
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p.1 #3 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Minolta Color Meters will give you the filter to balance... Of course, you've got to find a nice, used one. (I'm not sure how similar the Kenko iteration of the Minolta meter is, but that may be another option.)


Sep 05, 2013 at 05:44 PM
Policar
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p.1 #4 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Color temperature meter then refer to MIRED shift.

Not cheap, but not too expensive. $800 or so, if I remember right.

Consider other correction gels. CTS might have closer to the color you like than CTO. 1/2 CTO seems a bit strong (you should need 1/4 to 1/8) but obviously there are other factors. Also consider dimmers as they will drop the voltage and give you the "natural" look of under-driven incandescent filaments and you can just turn a knob and adjust to taste.

Harbor Freight sells "router speed adjusters" or something that are $20 dimmers for 650w lights and under, probably even ok on 1ks. Our local grip house marks them up and sells the so you know they're good. Variacs, imo, are too expensive, and non-film-specific variacs are often weird hybrids that are unpredictable (or so gaffers tell me).

You can check out this online toy to get an idea:

http://www.leefilters.com/lighting/mired-shift-calculator.html

I like 1/4 and 1/2 CTS.

There will always be variances in color temperature what with bounce and mixed lighting. Getting close enough should be close enough.

I'd get a small gel kit as a back up but my approach would be to buy a few cheap ($20/each) dimmers and adjust by eye to get the color temperature, then use scrims to adjust intensity. Seems like the easiest and cheapest approach, though color temperature meters are so cool and handy for adjusting magenta/green balance, too.



Sep 05, 2013 at 06:03 PM
Bearmann
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p.1 #5 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


I'm not sure how quickly you could do this, but take a photo in the ambient light of the room at a certain Kelvin temp. white balance (with no flash). Maybe start at about 2800 if it's fully incandescent lights. Check the photo on your camera. If the image is too warm, lower the temp and reshoot. If the image is too cool, raise it and reshoot. When you get something that looks right, make a note of the temp. Your gels should come with sheet which states what temp they convert 5500K flash to. Pick the gel that gets the closest.

Some prefer to shoot people with a half gel in incandescent light, ballance for that, and let the background take on a warmer glow.

Some people prefer CTS (straw) over CTO for their skin tones.

When bouncing off colored surfaces, I think you just have use your best guess, especially if the amount of colored surface may change from shot to shot, e.g. bouncing off a colored wall and white ceiling simultaneously.



Sep 05, 2013 at 10:08 PM
markd61
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p.1 #6 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


I use CTS as CTO always gives me blue/magenta shift.

That said, the real issue with event lighting is that it varies wildly. The problem is compounded with any bouncing.

A "muddy" color sounds more like low contrast and underexposure more than a real imbalance. A sample would help. Most lighting, if it is tungsten, is at about 2200K or even lower. Now we see a lot of CFLs that can be almost any color. They generally need about 1/4 magenta to compensate but that varies a lot.

There are endless numbers associated with our craft and endless ways to measure and TRY to compensate for them. At bottom you will make a compromise and shoot RAW to fine tune your images.

The fact that you gel at all means that you already have moved the color balance of your image to a far more pleasing tone (I hope) than your competition. Minor tweaking and some skill in post will get you the rest of the way.



Sep 06, 2013 at 04:30 AM
BrianO
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p.1 #7 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Turbohamster wrote:
The only way to really tell exactly what colour temp the ambient light is to shoot a grey card using the ambient light.


That's a pretty bold statement, and -- as with most absolute statements -- it's not true. It's one way, but not the only way.

Someone already mentioned using a used Minolta color meter, and there is also the current-production Sekonic equivalent:

http://www.sekonic.com/products/c-500r/overview.aspx







Of course, at almost $1400 MSRP this is an expensive solution, but it is very precise, and very fast.



Sep 06, 2013 at 05:10 AM
 

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Elan II
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p.1 #8 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Another vote for CTS gels in place of CTO. Color temperature can be achieved with different tones of equal warmth, so a Kelvin measure alone is not guaranteed to produce a true color match. CTS is closer in tone to incandescent lighting than CTO is.

In a dark room or at night, I use 1/2 CTS to bring 5600k flashes close to the ambient incandescent lighting. Keep in mind that my fill color temperature is actually higher, but the result pleases the eye and the tones are accurate. At worse I make a color temperature adjustment in post, but my tones are correct.






Sep 07, 2013 at 10:39 AM
rico
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p.1 #9 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


The C-900 is precise but does not cover the incandescent range. Perhaps a CTB could facilitate the measurement, but a correction factor would then be introduced. I keep mine in the studio for balancing xenon flash through modifiers. No instrumentation will guarantee color matching on-the-fly, especially when bouncing off blue walls. Ambient is a bitch.


Sep 08, 2013 at 06:58 AM
BrianO
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p.1 #10 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


rico wrote:
The C-900 is precise but does not cover the incandescent range.


If you mean the C-500, mentioned by me above, it has a measuring range of 2300K to 20,000K.

Incandescent lights are typically 27003300 K, so there should be no reason for a properly functioning colorimeter not to be able to measure that range.

Maybe something is wrong with yours.



Sep 08, 2013 at 05:20 PM
ukphotographer
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p.1 #11 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


My Minolta has been balancing ambient to film/digital and ambient to flash for many years. If you want something that will work in providing the correct colour correction in any given situation then a colour meter is what you need.

Whether you have the time or inclination to use it and then just want to guess - then thats your prerogative.



Sep 09, 2013 at 01:40 PM
JBPhotog
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p.1 #12 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Bartlett Pair wrote:
I started gelling for tungsten to combat incandescent recently. However, I've found myself blindly always using 1/2 CTO by default. Sometime the light seems a little 'muddy,' which leads me to believe there is a color difference between the gel/ambient. Is there a best/fast technique to determine which gel strength to use? We do mostly weddings, so we need to quickly figure out the ambient color of a church etc.

Also, if I'm bouncing gelled flash off of something like a wood/beige ceiling, how should I adjust? Or what if the ceiling is blue, etc?


Bouncing off any coloured wall will induce an unbalanced reflective light, it's just the way it is. Diligent work in post can resolve most of these issues if you have a known standard such as a grey card captured in the same lighting. Do a scout or arrive early to capture your grey card then fix it all in post.

Incandescent lighting can vary widely due to filament types, age and colour temperature, there is no one size fits all. It is why you see colour meters used in the movie industry, they will balance each light source to a specific temperature. Also with the advent of Low E and CFL's, mixed lighting is pretty much assured in most locations these days. You will never be able to build a filter pack for each scenario on the fly.



Sep 09, 2013 at 05:19 PM
Bartlett Pair
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p.1 #13 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


Bearmann wrote:
I'm not sure how quickly you could do this, but take a photo in the ambient light of the room at a certain Kelvin temp. white balance (with no flash). Maybe start at about 2800 if it's fully incandescent lights. Check the photo on your camera. If the image is too warm, lower the temp and reshoot. If the image is too cool, raise it and reshoot. When you get something that looks right, make a note of the temp. Your gels should come with sheet which states what temp they convert 5500K flash to. Pick the gel that gets
...Show more

Thanks everyone for the very helpful input! The color meters look awesome, but for now I'm just going to stick with Bearmann's approach. Also, I'll be switching from CTO->CTS, which seems to be the majority opinion across the web for Canon shooters to reduce red cast.

As for bouncing off of wood ceilings, I'm still trying to determine the best approach. For a wedding reception where I have two off-camera flashes gelled to the room's incandescent, should my on-camera bounce flash perhaps be ungelled since the ceiling will add warmth?

When bouncing off of a warm wall/ceiling, will adding a cooling gel help negate the warmth or are there too many variables to make this a viable solution?

Anyone have suggestions for the best place to buy CTS? I was thinking of buying full sheets like this Rosco Cingel 20x24 and cutting it myself, but if anyone has a precut/labeled solution that would be cool too.



Sep 10, 2013 at 03:27 PM
Bearmann
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p.1 #14 · How to Meter Exact Tungsten Gel (1/4 v 1/2 v 1)


I'll usually try shooting ungelled or with a half gel instead of a full gel when shooting off warm wood surfaces. It's still a matter of experimentation. Sometimes it works pretty well. Other times it doesn't look so great. If I have a colored wall which I know will give me a WB problem, I might turn up the iso, open the aperture, but primarily lower the shutter speed so that the ambient light to flash light ratio is increased (i.e. ambient primary with flash fill instead of flash primary with ambient fill). Of course, that's only when the ambient light is sufficient in quantity, looks nice, and is not strangely colored .If you are going to be bouncing off the same wood surface consistently (a succession of photos will have a similar WB), then do your experiment with the flash on while bouncing off that surface, then choose which gel to use. Of course, if you do that you will not be matching the ambient exactly, but trying to match the combination of mixed light. Any gel you add to change the flash will only be partially effective because you are only changing the flash part of the mixture, while the ambient remains unchanged. Really, after a while you just wing it, because you will have a feel for what's needed and what works.


Sep 10, 2013 at 03:53 PM





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