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Color Temperature Meter


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#1 Derek Leffew

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Posted 21 August 2007 - 11:51 AM

Can anyone recommend a cost-effective, hand held, color temperature meter for lighting for video? I posted in The LightNetwork and was told of the Minolta Colormeter III, but it has been discontinued.

I've run followspot for many shows, including network-televised award shows and HBO specials, and the only time I know of a Color Temp Meter being used was on the first leg of Bette Midler's Kiss My Brass tour; they used House Fixtures and House Operators. On the second leg they used 2 Lycian 1290s on a truss over the mix position and brought their own operators for Bette, and 4 House Spots, but I don't know how/if they metered them as I only worked the load-in.

Once I get the color temperature meter, how do I use it? Can anyone explain "mired shift" to me? Most of the corporate shows I do are heavy on Imag, and I have found that washing the stage with 750w Source4s with L202+R119; and 1/2 CTO + 1/4 Minus Green in the Super Trouper Followspots looks good on camera, depending on who's shading/op'ing the CCUs.


To everyone, what's YOUR favorite Color Correction trick? Do you tape a flavor of Minus Green to the front of followspots?



Thanks.



.
--------
visit my website at http://www.derekleffew.com
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#2 John Sprung

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Posted 21 August 2007 - 01:06 PM

The lowest cost way to go is just to use heavy red and blue filters with your regular light meter. Take a reading thru the red filter, and another thru the blue, and compute the ratio. Calibrate it using known good sources, or against a good borrowed meter.



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#3 Stephen Murphy

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Posted 21 August 2007 - 01:09 PM

You can still find Minoltas on ebay from time to time.
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#4 Barry Cheong

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Posted 21 August 2007 - 01:11 PM

There's a company called Kenko that seems to have taken over the design of the old Minolta IIIF color meter. They look almost identical.

Gossen also makes one. They're both pricey.
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#5 Michael Nash

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Posted 22 August 2007 - 05:31 PM

I do film/video not stage lighting, so I'm coming at this from a slightly different point of view.

The cheapest color meter I've found (and use) is my digital still camera. Don't laugh, it works -- instead of having to correlate numbers and densities of gels, it shows you in real time any color shifts you've got going relative to your chosen white balance. It may not be the precise color rendition of whichever film or video system you're using, but it gives you more than enough reference information to find errors. You just have to have a little experience to know where to start your color correction (orange-blue or green-magenta). If you want or need precise numbers (like when testing HMI's before a show), then you'll want a "real" color meter.

I've never noticed any green shift from xenon lights, but perhaps the combination of gels and the camera+projection shifts the color rendition a little. You're trying to balance what the audience sees live and what ends up on the screen, so the technical setup of the Imag is a big factor. If the cameras are white balanced for tungsten you need more CTO on your xenons to look "correct," but then the projection will probably be closer to 5600K, which will make everything look bluish under tungsten conditions. Your minusgreen lighting problem may well actually be a projector RGB problem! You really need to coordinate with the video engineers to see that the signal is correct at every step along the way, rather than second-guess color correction based on what you see projected.

The Minolta color meter reads color along two scales; orange-blue (color temperature) and green-magenta (the spike in the spectrum of fluorescent sources and the correction needed for it). There's a scale on the back that shows the density of gel needed to correct for the number shown.

Honestly in 20 years of shooting I've never used mireds to calculate any corrections. After a while you just learn the inherent color temperatures and spectral "spikes" of the various sources out there. Correcting one to another becomes pretty academic. But maybe that's just me.

http://en.wikipedia.org/wiki/Mired
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#6 Richard Andrewski

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Posted 23 August 2007 - 06:12 AM

There are used Gossen's on Ebay all the time and they're pretty reasonable...
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#7 Hal Smith

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Posted 23 August 2007 - 09:27 AM

I would recommend a Minolta Color Meter II if only because Quality Light Metric (323-467-2265) in Hollywood can calibrate them. Apparently the Color Meter III's require special software and test fixtures to calibrate and only Minolta had them.

I bought my II off eBay for $275 expecting to send it to Quality for calibration. They charged me $90 for a minor repair and calibration. Mine read new GE Chroma 50's at 4100K before calibration and now reads them between 4950 and 5050K. Like all precision test equipment it's recommended to calibrate a color meter yearly.
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#8 Derek Leffew

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Posted 23 August 2007 - 11:02 PM

<snip>

The cheapest color meter I've found (and use) is my digital still camera. Don't laugh, it works -- instead of having to correlate numbers and densities of gels, it shows you in real time any color shifts you've got going relative to your chosen white balance. <snip>


Thank you for your response. It helps me confirm I've been doing it right all along--the eye is the best "decider". I bought the Light Meter just to prove to myself that the sources were balanced to one another in intensity. Through experience I've learned that a 3250° incandescent source with 1/2 CTB and a Xenon Super Trouper (5600°) with 1/4 Minus Green and 1/2 CTO match pretty well. As you said, the camera, shader, switcher, and projector are all in the chain and each hurts or helps what I see on the big screen, or on my monitor (other than the projector).

I wasn't intending on spending $1000 on a Color Temp Meter that I might use once a month anyway. If I happen to come across a used one for a good price, I'll consider it.

Once again, thank you.

Derek
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#9 Derek Leffew

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Posted 26 August 2007 - 04:03 AM

I do film/video not stage lighting, so I'm coming at this from a slightly different point of view.

The cheapest color meter I've found (and use) is my digital still camera. Don't laugh, it works -- instead of having to correlate numbers and densities of gels, it shows you in real time any color shifts you've got going relative to your chosen white balance. It may not be the precise color rendition of whichever film or video system you're using, but it gives you more than enough reference information to find errors. You just have to have a little experience to know where to start your color correction (orange-blue or green-magenta). If you want or need precise numbers (like when testing HMI's before a show), then you'll want a "real" color meter.

You're absolutely correct. I inadvertently proved that when taking pictures of a white 5600°K Xenon Super Trouper beam with my camera on the wrong setting. And the picture showed blue halation around the beam that I could not see. Only problem was I had to import from the camera to the laptop to see the issues. The camera's built-in LCD screen just doesn't have the clarity.

See the pictures here. http://www.derekleffew.com/spotbaggy

Thanks for all the help,
Derek

Edited by Derek Leffew, 26 August 2007 - 04:04 AM.

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