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Measuring the Tint of Lights


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#1 craig bass

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Posted 26 May 2017 - 02:01 PM

I have spent a year, on and off, attempting to find a way to measure the tint of my LED's and Fluorescents. I rented a Sekonic C-700, only to find that this was not capable of reading the green to magenta bias. This was roughly a year ago. I just called Sekonic customer support to ask if an update had been made: whoever I spoke with told me that the meter was only capable of reading Kelvin.

 

I have also purchased the Luxi Metering Sphere for the iPhone, pairing it both with the Luxi App and the Cine Meter II App. Every time I take a reading with this device, I receive a different response. I could stand in the exact same spot, and take the same reading twice only to receive 2 different answers.

 

I am at a point where I am totally lost, and feel that I cannot maximize the potential of my entire lighting arsenal. 

 

Can anyone help?

 

Thanks!

 

Craig


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#2 Yann Cainjo

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Posted 28 May 2017 - 11:59 AM

Hi Craig

 

We made last year an independent study on photometric and colorimetric performance of LED lights published by CST in France (English & Spanish translations included) :

http://www.<span>cst...Internet-v2.pdf

 

For this study we used 4 different spectrophotometers :

 

Sekonic C700

UPRTEK MK350N+

Minolta CL-500A  (laboratory spectrophotometer)

Specbos 1211 (laboratory spectrophotometer)

 

We measured the Magenta/Green bias with the UPRTEK, because it was the more accurate.

 

There are 2 UPRTEK spectrophotometers usable for film industry with the Magenta/green calculation :

UPRTEK MK350N+

UPRTEK CV-600

 

We didn't use the SEKONIC C-700 to evaluate the magenta/green bias because there was a problem with the former C-700 firmwares.

 

Maybe the last firmware update solve it ?

 

Regards

 

Yann Cainjo
DP, Photographer | Paris


Edited by Yann Cainjo, 28 May 2017 - 11:59 AM.

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#3 Stuart Allman

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Posted 30 May 2017 - 01:55 PM

Craig,

 

What the C-700 can do is measure the color of your light and suggest a Lee filter gel to get you to a target Kelvin color temperature.  I don't have very much experience using this feature, but I think it should be able to specify plus and minus green gels.

 

Stuart Allman

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