How Do Video Lights REALLY Perform?

One of our reps left a neat toy in the shop for us to play with; a UPRTek MK350N Spectrometer.  This handy dandy tool measures spectral response, correlated color temperature, color rendering index, light output, dominant wavelength, and CIE coordinates.  It's every lighting geek's dream!

 

Many video lights claim to have a 5500K or 3200K CCT, but do they really?  How good are LED and fluorescent bulbs...really?  The data below doesn't lie.  I've labelled each data set for convenience and comparison.

 

Here are a few points to watch.

1. Tungsten still produces the highest/best color rendering but the color temperature drops quickly with dimming.  Also note that the color temperature isn't necessarily 3200K as most people assume.
2. LEDs are reasonably stable over dimming.  Note that all "daylight" LEDs have a large blue spike around 450nm and die off starting around 640nm.  Of the group, the Mole-Richardson fixture had the most on-target CCT and best spectral characteristics.
3. The CCT of the HMI fixture depends on which mode you have the ballast set to run in.  The CCT also changes with dimming.
4. All fluorescent bulbs have a spike in green and blue, as shown in the Kino-flo pictures below.  We have tested a couple fixtures and found it's pretty typical for the Kino-flo K55 tubes to actually be closer to 7000K!  Commercial lighting fluorescent bulbs (not shown, but I tested them too) are much, much worse!



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Arri 650W full brightness.

 

Arri 650W dimmed by about 50%.

Film Gear HMI with ballast set to flicker free

 

Film Gear HMI with ballast set to flicker free and dimmed 50%

 

Film Gear HMI with ballast set to 300Hz operation.

Film Gear HMI with ballast set to silent

 

Film Gear LED

 

Film Gear LED dimmed to 50%

 

Kino-flo Diva with K55 fluorescent bulbs

 

Kino-Flo Diva with K32 fluorescent bulbs.

 

Mole-Richardson LED Tweenie daylight

 

Mole-Richardson LED Tweenie daylight dimmed to 50%

 

Nila Varsa

 

Nila Varsa dimmed to 50%

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