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Color Temperature Meter


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#1 Jeremy Drake

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Posted 29 January 2008 - 12:08 AM

Or if you have one... how well does it work?


I'd really like to get my hands on one and try it out.
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#2 Chris Keth

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Posted 29 January 2008 - 12:50 AM

Or if you have one... how well does it work?


I'd really like to get my hands on one and try it out.


Well, I would expect most places that carry light meters would carry color temp meters. Minolta used to make one that became quite the standard.

They work. I don't know what I'm supposed to say. :blink:
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#3 Mike Williamson

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Posted 29 January 2008 - 01:01 AM

I think Filmtools has one, look under Gossen meters.

www.filmtools.com

I've used one meter before, I think it was a Minolta. It gives you two readings: one for color temperature, one for the magenta/green axis. I've found them to be pretty accurate for the limited uses I've put them to which has mostly been checking lamps at the rental house, but I don't own one and I've never brought one to set. I'd imagine that their weakness would be with lights that have a discontinuous spectrum, specifically fluorescents, mercury vapor or sodium vapor lights, but that's a guess.
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#4 John Brawley

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Posted 29 January 2008 - 04:04 AM

Or if you have one... how well does it work?


I'd really like to get my hands on one and try it out.



I have a Minolta Colour temp meter. It's a model II which i bought second hand for $500. The III was selling for over 3k (all aussie dollars)

So they are by far the most expensive meter you'll will probably own. Most gaffers will carry one anyways, and few DP's feel the need to carry them.

I bought mine because it was cheap and i was mucking around with trying to build LED based lights for film and TV applications, so I wanted to be able to check the colour temp of supposedly daylight white LED's.

So what a colour temp meter will tell you is the white point, in degK to make an image look white on a given shooting format, digital or film.

It will also tell you if there is a bias towards magenta or green at that white point. You might find a fluro source that is 4000 degK but has +15 points of green

It's common for example to bowl into a location like a shopping centre where you have ti use the existing light, and you want to then match the light with your own lights.

So a colour temp meter will tell you what the white point is, and how much green (usually) there is in those pesky fluros. You can then calculate what you need to do to match your own lights to this white point and offset.

What it WON'T tell you is the CRI or Colour reference/rendition index. In other words, how even across the spectrum of colours the light source is. Fluro's usually are very deficient in red for example. So even though you may know the colour temp and the green spike, it won't show you that it's only emitting 85%of the available spectrum of colour. Your coke can won't look so great, even though you've got the white balance spot on and there's no green cast.

jb
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#5 Hal Smith

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Posted 29 January 2008 - 10:21 PM

I bought a Minolta Colormeter II off eBay for $325 and had it calibrated at Quality Light-Metric in Hollywood. It now reads new GE Chroma 50 5000K fluorescents between 4950 and 5050K and fresh 3200K quartz lights right on the money. Sunlight varies but guess what? Sunlight IS variable.

I wouldn't buy a used meter without planning on getting it calibrated. I have heard that the newer Colormeter III's cannot be calibrated because Minolta never released the calibration software to independent calibration labs.
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#6 Jon Rosenbloom

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Posted 30 January 2008 - 10:28 PM

I'm still smarting from the $1400 I spent on my Gossen 3 color temp meter a few weeks ago. Minolta no longer makes light meters, and there were none at the used equipment counter. But I'd been putting off that purchase film after film. I'm not yet convinced that it's worth it. I checked out an hmi today and found that it was running very cool, so I had the rental house give me a piece of 1/4 orange to go with it. Big deal. As for the green/magenta scale, I have to wait until I see dailies. I corrected some flo's according to what the meter read, but to my eye it looked as if I was going way into magenta. We'll see.
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#7 Hal Smith

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Posted 30 January 2008 - 11:31 PM

I'm still smarting from the $1400 I spent on my Gossen 3 color temp meter a few weeks ago. Minolta no longer makes light meters, and there were none at the used equipment counter. But I'd been putting off that purchase film after film. I'm not yet convinced that it's worth it. I checked out an hmi today and found that it was running very cool, so I had the rental house give me a piece of 1/4 orange to go with it. Big deal. As for the green/magenta scale, I have to wait until I see dailies. I corrected some flo's according to what the meter read, but to my eye it looked as if I was going way into magenta. We'll see.

One thing I've noticed about my Minolta is that its latitude is a bit restricted. I haven't run any scientific tests yet but it seems it goes whacky at very low and very high light levels. I'd guess about 10 FC low end and 1000 FC high end. For instance this starts to show up if you get real close to a bright light source in the desire to block out other sources.
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#8 John Brawley

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Posted 30 January 2008 - 11:37 PM

I'm still smarting from the $1400 I spent on my Gossen 3 color temp meter a few weeks ago. Minolta no longer makes light meters, and there were none at the used equipment counter. But I'd been putting off that purchase film after film. I'm not yet convinced that it's worth it. I checked out an hmi today and found that it was running very cool, so I had the rental house give me a piece of 1/4 orange to go with it. Big deal. As for the green/magenta scale, I have to wait until I see dailies. I corrected some flo's according to what the meter read, but to my eye it looked as if I was going way into magenta. We'll see.



I think it's always hard to trust your eyes.....I find the meter is normally right in these situations.

The other time you really want a CT meter, is when you have multiple HMI's of the same lamp repeating something. Say, a row of 4K pars at a regular interval off into the distance. You want them to all look the same. Pefect example of when you want to meter to match them all.

jb
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#9 Tony Brown

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Posted 31 January 2008 - 02:28 AM

Minolta no longer makes light meters,


The meters are still made but branded Kenco.... http://www.adorama.com/KNKCM3100.html
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#10 Mike Williamson

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Posted 31 January 2008 - 02:51 AM

What's your feeling on color meters Tony? Do you use them much on set?
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#11 Tony Brown

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Posted 31 January 2008 - 04:34 AM

What's your feeling on color meters Tony? Do you use them much on set?


Maybe once every 3 years... you can drive yourself nuts with them. On most occasions I'd rather trust my eyes as far as blue/orange goes though I find that harder for Magenta/green. I used mine recently in a bank in Istanbul where it was impossible to replace the all the overheads and it looked ridiculous switching them off. However the meter indicated I need half minus green which looked WAY too much. The gaffer checked with his meter - same reading. I went with quarter and it bugged me all day... still looked way over the top. Sure enough in the grade there was a little magenta/pink where the sources were reflected in their housings but the rest graded ok. Trouble is if you dont carry one you'll need it, carry it and you dont trust it anyway..... better to have the information and make a reasoned decision than just guess though....

Luckily I rarely find myself in a situation where I need one. Obviously the best option is to test. I know its usually a time factor but it really only takes a few feet of film.... even through a still camera loaded with some vision 2......
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#12 Jon Rosenbloom

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Posted 01 February 2008 - 06:05 PM

I remember working for Vilmos Zsigmond on Melinda & Melinda, and he seemed quite the stickler for precise color-temp readings. If there's anyone to emulate ...
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#13 John Allen

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Posted 02 February 2008 - 10:15 AM

ebay.com......you can get just about anything on ebay and it's cheaper.
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#14 Scott Willis

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Posted 10 February 2008 - 12:46 PM

What it WON'T tell you is the CRI or Colour reference/rendition index. In other words, how even across the spectrum of colours the light source is. Fluro's usually are very deficient in red for example. So even though you may know the colour temp and the green spike, it won't show you that it's only emitting 85%of the available spectrum of colour. Your coke can won't look so great, even though you've got the white balance spot on and there's no green cast.


question. why is it that the human eye doesn't detect the missing red under consumer fluorescents? is the internalized color correction that good?

just curious.
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#15 John Brawley

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Posted 10 February 2008 - 03:06 PM

question. why is it that the human eye doesn't detect the missing red under consumer fluorescents? is the internalized color correction that good?


That's the whole point. Basically because that part of the spectrum is missing from the light that's being cast off by the fluro. Not all of it, but it's got a flat spot compared with other sections of the spectrum. It's not that our eyes aren't able to detect it. The actual light doesn't output the same amount of red light compared to green and blue say, which can then illuminate that part of the spectrum so that we can perceive the colour. If the light doesn't throw off any red light or is feeble, then anything red in the scene isn't receiving the same amount as something that is green or blue.

jb
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#16 Hal Smith

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Posted 10 February 2008 - 03:20 PM

ebay.com......you can get just about anything on ebay and it's cheaper.

But get it calibrated, my eBay Minola Colormeter II was way off but came back from Quality Light-Metric right on the money.
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#17 John Sprung

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Posted 12 February 2008 - 02:59 PM

question. why is it that the human eye doesn't detect the missing red under consumer fluorescents? is the internalized color correction that good?

Yes, and it's mostly your brain that's doing the compensation. Part of it is that the cone pigments and observed matching functions have a lot more overlap, and less sensitivity under 400 nanometers than the three layers of color film, too. Even more amazing, your brain handles the extreme green mercury spike at 546 nanometers.

There are some low budget alternatives to the expensive color meter. If you can white balance a little video camera to a known source and lock it in, the picture will tell you what color you're getting. Just try gels on the lights until it looks OK. The spectral spikes of mercury or sodium you can see by using diffraction off a junk CD or DVD. You'll know what the problem is, just not how big it is. What the fancy CT meters do is measure through extreme red and blue filters, and look up the CT from the ratio of red to blue. I haven't tried this, but in theory you could do that by hand, just by measuring through extreme red and blue gels, and making a table of ratios to known CT's. Worth a try, but the one possible issue is that even the best light meters may not be precise enough.



-- J.S.
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#18 Alexandros Angelopoulos Apostolos

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Posted 11 January 2016 - 12:07 PM

I remember working for Vilmos Zsigmond on Melinda & Melinda, and he seemed quite the stickler for precise color-temp readings. If there's anyone to emulate ...

 

What kind of readings did he used to do?


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#19 Adrian Sierkowski

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Posted 11 January 2016 - 02:27 PM

I have a color meter-- and I do use it. Not a lot, not a ton, but it comes out here and again. It's a Minolta II which I got for $300 I believe, used. I will eventually upgrade to the new Sekonic model.
I use it for floros, I use it on multiple HMIs (when it really matters-- which isn't as often as I thought) and I can justify carrying the damn thing because what's easier-- paying for it and using it maybe once on one gig where, damn, it made it look great, or not using it, trying to do it without all the available information, and then having a really pissed client who certainly won't be raving about your work-- hell, which one of those is cheaper to absorb in the end?

 

Just like a light meter-- which I also still carry and only sometimes used-- because after awhile you just know if you have enough exposure and how it looks-- it's a tool which gives you information which you then make the choices on how to act upon based on more variables than one cares to count. Can you shoot without one-- sure you can-- will you be constantly checking every light-- no of course not, but you'll use it, sooner or later.


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