I've just been watching the West Indies and Sri-Lanka match on SKY (June 2018) and the game's just been stopped because of poor light. The 3rd umpire came out with a light meter and measured the light and the on-field umpires called a halt to the game.
As a photographer who knows a lot about light and characteristics of light I was interested in knowing what the light reading might be in terms of the EV (Exposure value). From what you can see when the reading is taken, it looks like a bog standard light meter using an incident reading e.g. the meter reads the light that falls on the meter measured through a translucent dome.
Doing a little research I found a few articles and they offered nothing. In fact the whole thing sounds a bit wishy washy, when in fact in terms of the light which can be measured exceptionally accurately with a basic light meter costing in the region of about £150 it should be a really basic and rigid set of parameters.
Light, having traveled 93,000,000 miles or so from the sun is amazingly even right across the globe because of some basic physics - 'Inverse square law'. There's a basic premise in photography based around this physics aspect generally known as the Kodak Rule . The light having traveled so far hardly differs in EV terms from The Arctic to the equator and if the sun is out and you have a blue sky the Exposure value is F16 at 1/125 at 100 iso. Anyone who's ever taken pictures and taken it a step or two from point and shoot will recognise these values. The thing to take from this is that irrespective or whether you're at Headingly or Newlands the light in those conditions is the same.
It gets more complicated once there is cloud cover and then more so once the sun dips in the sky. As the sun dips in the sky and the atmosphere cools, the air becomes saturated with moisture (Dew) and the sunlight increasingly has to pass through this now dense moisture laden atmosphere. This makes the light diffuse and so softens and reduces the lights intensity giving a lower EV reading (less light). Furthermore, the lower atmosphere is also laden with pollution particles and the combination of both dew and the pollution enables us to be able to stare at the sun in it sets and is rendered warm and orange by all these atmospheric factors.
The thing that bamboozles most people is the fact that unlike light meters and photographic equipment, our eyes have more than 65,000,000 years of development behind them. This means they're pretty well equipped to work in a massive range of light levels before we start to recognise that it's pretty dark. Given that we want to see a Test match out to the very end, our eyes would be looking at the light levels in many of these scenarios and concluding that it's still light enough to play. Needless to say this form of measurement is very subjective and differs from one person to another dependent on how good your eyesight is and how well your cones work.
What I was hoping to find on the web was an EV value that most of us could make sense of. If you shoot a lot of pictures and try to do so at high quality you'd be using light sensitive capture mediums that are working at 100 iso. In which case you'd probably know that in the poor light scenario it starts to get sketchy at a point when you're having to shoot at F2.8 at 1/60 at 100 iso. But to the human eye this still looks pretty bright.
Looking at this article here this paragraph kind of indicates how daft this law is...
"Instead, the instrument only indicates whether the light conditions have improved or worsened, and it is the prerogative of the umpires to make the judgement on whether play can go on or not in the given conditions. What the light meters do offer is the option to the umpires to back up their subjective assessment of the playing conditions with the light meter readings as their justification".
Given that it comes down to the subjective opinion of the umpire, the game is then subject to age of the umpire and the condition of the cones in his eyes. If he's an older umpire his cones are going to be potentially shot and he'll be calling the game off in potentially moderately poor light that a young person would still easily be able to play in.
But, if it came down to a precise reading from a light meter, you're then subject to the vagaries of the light and the fact that it is massively affected by the atmospherics, primarily cloud cover and movement. The light over a matter of minutes in the middle of the day can go from a exceptionally good value to a very poor value and back again. The question would be - do you stop the game as soon as the light dips below the 'Official meter reading' if one existed, or do you rely on the umpires judgement?
