I remember the incredulous look on the face of my mother and family, when they learned that part of my uppity all-boys private school education was to spend a considerable amount of time at one point, on the hazards of drugs. But I sort of understood because I used to while away some of my homework hours listening to Dark Side Of The Moon. If you were a young person in the 70s, you didn’t need this sort of education because Pink Floyd was a living beacon of what recreational drugs could do to a person.
That album cover also happened to be some introduction to understanding light, weirdly. The famous beam of light hitting a Prism then showing the rainbow of colors within the beam coming out the other side. If you’re a freak, like me, you’ll probably estimate that that light bean is sunlight given the evenness of the colors coming from the other side. This brings us neatly to the often overlooked topic of the Color Rendering Index (CRI), and how its ratings are of far more importance than most tend to give them in the photographic world.
When thinking about light and light sources, we tend to think about them in terms of intensity, power, and temperature. This is all well and good and those are important factors to consider, but perhaps just as useful would be the measure of a light source’s color characteristics in terms of a CRI rating. In the most simple terms, CRI measures the ability of a light source to show an object’s color naturally or ‘realistically,’ typically measured compared to a standard reference source like daylight.
A CRI of 100 is the maximum and more perfect value, and you’ll typically get very high ratings in the high 90s from an incandescent light source, but fluorescent and LED lights typically have a much lower rating – between 60 and 75, from my experience. Generally, you’re looking for 85 and above for a good light for photography. So, the good folk over at DIY Photography have put together a video and associated post explaining a bit more about CRI, why it matters, how it’s measured using a Spectrometer, and how you can test it.
They’ve also tested various LED light panels to show how they are not all made equal. The cheapest of the lot came in around 71, and the most elite was 96, which is highly impressive. (Incidentally, the new Icelight V2 has a CRI of 96 also which is partially why it’s so impressive – learn about it here). It’s great to see on video just how much of a difference a high CRI rating makes a picture, and this is something that should be considered with every light you buy, especially in this age of LED product proliferation.
See the full post here, and the video below.