CRI ratings – Testing the Pergear MTL900 Pro LED Light

Matt Allard testing the Pergear MTL900 Pro light ©Uchujin-AdrianStorey2016

A while back I needed to buy a new light for shooting interviews that was compact, easy to carry (I’m usually shooting as a 1 man band – no client money for assistants) and yet soft and flattering on the subject. I’d been pretty impressed by the Westcott Ice light but was unwilling to pay the $500 or so they cost at the time so went searching for an alternative. As always the internet and China provides and I discovered the Pergear MTL900 Pro at only $70 and it seemed ideal, in fact in many ways it seemed a steal – 2 batteries included, IR remote control included, CTO gel included (a $30 extra for the Westcott) and a nice looking carrying bag – Ok, sold!
On receiving it I was pretty impressed. The build quality was excellent and the ability to run it from Sony NPF batteries or even from an external USB battery pack made it great for use on longer interviews.
But how was the light quality?
The problem of course with cheaper LED lights for video is the CRI rating (Colour Rendering Index – more on that in a second) or more specifically their ability to output a flat enough color spectrum to provide flattering skin tones, so I was a little concerned about the Pergear light.

In use it seemed pretty good, to my eye it looked great with no noticeable colour cast or weird skin tone issues. But as I well knew my eyes (especially these middle aged – god damn it I need bifocals eyes) could be decieving – but how to check it scientifically? I didn’t have access to a high end light meter/spectrometer that could analyze it.
I continued using it on a number of shoots and was always pleased with the results but that nagging voice shouting “What is the CRI rating??” wouldn’t go away.

Fast forward to a couple of days ago and I had arranged to tag along with Matt Allard (Slightly well know camera man from News shooter) to NAC rentals in Tokyo as he tested out a new Arri light panel using a Sektonic Spectromaster C-700 high end spectrometer (a mere $1,300!!)……An ideal opportunity to test the Pergear too!

Before we get into the results and a comparison of the Pergear to the Westcott Ice Light it is necessary for a brief aside about CRI ratings and light analysis.
There is a very real argument that says that the CRI ratings posted by most manufacturers are essentially meaningless in real terms as they only include the colour rendering results in the R1 – R8 part of the spectrum (see results below) and that of equal (if not more) importance for us as cinematographers are the R9 (Red) R13 (Caucasian skin tone) and R15 (Asian skin tone) bands, the results of which are rarely included in published CRI ratings.
It is also important that if a light says it is 5600K that it is actually 5600K and if there is any overall colour shift – known as the CCT rating (Corelated Colour Temperature), which for most LED lights is usually towards green – a very unflattering colour for skin tones.
For a more detailed explanation, Google is as always, your friend (in the”finding information” sense at least) but the CRI Wikipedia page is a good place to start.

The tests we performed were not completely scientific but we used a black non reflective room with no other light sources and measured both lights from 1m away.

Anyway lets look at some results!

First up Colour rendering:-

PERGEAR MTL90056_01_6193K_ColorRenderingWESTCOTT ICE V1_01_5202K_ColorRendering

As you can see the conventional CRI rating for both lights is pretty good 89.0 for the Pergear and 89.8 for the Westcott. Usually anything over 90 is considered very good, so both of these lights are good. In terms of the measured colour temperature which should be 5600K both lights are quite a bit out – 6193K for the Pergear and 5202K for the Westcott. Interestingly they both score well in the R9, R13 and R15 bands.

Spectral Distribution graphs:-

PERGEAR MTL90056_01_6193K_SpectralDistribution

WESTCOTT ICE V1_01_5202K_SpectralDistribution

Here we can see that the Westcott puts out a more even distribution of wavelengths and the fall off towards the red end is less pronounced and severe than the Pergear.

Side by side data from the Sektonics:-

 

Pergear MTL900 Pro Westcott Icelight vrs 1
Screen Shot 2016-03-25 at 09.57.00 Screen Shot 2016-03-25 at 09.56.42

Couple of things to note in these final tables – The Pergear is significantly brighter than the version 1 of the Icelight (look at the Illuminace figures). The Westcott has a very small overall shift to Magenta whilst the Pergear has a reasonably large shift towards green that probably negatively affects skin tones slightly (see the CC Index figures).

Overall from my admittedly not super well informed position I’d say the Pergear does remarkably well for a light that only cost me $70. Is the $500 Westcott better? well, yes slightly, but $430 better?
In the end it comes down to how it looks in use and after having used the Pergear for several months I have to say I’m happy with it.
Here are a couple of ungraded frame grabs from interviews shot using the Pergear as the key light.

Nakajima Hiroyuki interview screenshot

Shinzan Roshi interview - screen shot

And….just for fun a photo of me looking like an idiot wielding the Pergear like a lightsaber :)

 

Big thanks to Matt Allard for inviting me to come and test the Arri lights with him, for testing my Pergear light and his Westcott light, providing me with the figures from the Sektonics Spectrometer and for helping me to understand the results.

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