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Measuring Light

Posted By: renosteinke

Measuring Light - 02/19/09 02:01 AM

A recent job made me wonder ...

First, I do have a use for a light meter, to measure overall lighting levels. No problem there; sources are many.

However ... is there any reasonably portable, and affordable, way to measure the color temperature of the existing lights?

I ask this, having just gone through a great deal of frustration on a job ... apart from the issue of removing a bulb for examination, it seems that many bulbs are not identified as to their color temp - making matching a challenge.
Posted By: HotLine1

Re: Measuring Light - 02/19/09 02:31 AM

Hmmm. I gave a quick check of GELighting.com; no mention of anything to measure color temp, just an explanation.

I can't remember ever seeing any type of meter to do that. All I have ever used (and thought of) was a basic light meter.

I have a BEHA, small handheld analog, that's OK. For serious work a BEHA digital 93-1065F. Both are 'old' and have served me well. I still have both.

Posted By: Trumpy

Re: Measuring Light - 02/19/09 03:27 AM

John,
Photographers use colour temperature meters, if that is any help.
Posted By: renosteinke

Re: Measuring Light - 02/19/09 04:05 AM

Thanks for the hint, Mike .... alas, those things are selling for over a thousand dollars! Not quite my idea of 'affordable.'
Posted By: JoeTestingEngr

Re: Measuring Light - 02/19/09 05:29 AM

I haven't really considered color temperatures since my broadcasting and post-production days. There, you really want all your monitors setup the same way. If you already have to buy a light meter, you might be able to determine color temperature using filters: 1st reading, no filter. 2nd reading, red filter. 3rd reading, blue filter. I think that the transmissivities would shift from red towards blue with increasing color temperature. I don't know if there are convenient charts out there for specific density filters or not. You could probably check light sources of known color temperature, note the percentages, and develope your own reference.
Joe
Posted By: frenchelectrican

Re: Measuring Light - 02/19/09 06:06 AM

John., here one item i will post it for now and when I find more items I will add to the list here


Here the first one .,, colour temp chart

Merci,Marc
Posted By: Trumpy

Re: Measuring Light - 02/19/09 07:47 AM

John,
One thing that is hardly ever touched upon, is the CRI (Colour Rendering Index) of a light source.
At the worst end of the scale is light sources like Sodium (low and high pressure) up to lamps like Metal-Halide and tri-phosphour(sp?) fluorescent tubes.
I think a few years back I wanted a discussion on this very subject, but it died, lighting has come a long way over the last couple of years, more lumens/watt and with a better choice of colours.
Posted By: SteveFehr

Re: Measuring Light - 02/19/09 01:53 PM

I wonder... a lot of digital cameras these days feature histograms and automatic white balance. Do any have a built-in color temperature reading? Maybe you just need a new camera!
Posted By: ghost307

Re: Measuring Light - 02/19/09 03:39 PM

That brings back memories of the "dumbest smart person" I ever met.

We were designing a workshop in a large office complex and the directive from the guys who would be working in that shop was to use 4100 degree fluorescent lighting in 1 particular room.
The Architette (AKA Ms. Architect) asked if we needed to increase the HVAC in that room if the lights were going to be that hot.

smile smile smile
Posted By: Retired_Helper

Re: Measuring Light - 02/19/09 07:45 PM

Originally Posted by ghost307
That brings back memories of the "dumbest smart person" I ever met.

We were designing a workshop in a large office complex and the directive from the guys who would be working in that shop was to use 4100 degree fluorescent lighting in 1 particular room.
The Architette (AKA Ms. Architect) asked if we needed to increase the HVAC in that room if the lights were going to be that hot.

smile smile smile


By any chance a RISD grad? wink
Posted By: ChicoC10

Re: Measuring Light - 02/21/09 01:40 AM

I just bought my wife a new camera that shows histograms. I have to look into that.

One of my favorite things (not) is attempting to explain why warm white is 3000K and cool white is 4100K.
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