Photography & Cinematography 101 -
It's All About The Light - 3
There are numerous types of cinema lights. Each has strengths and drawbacks.
Except for LED lighting, the main types of set/studio lights were created to work with film.
Film needs light. It needs LOTS of light.
Whereas digital formats are very sensitive to light over-exposure. This is due to a parameter called "Latitude" and I'll explain it in a different card.
The light in this shot is an HMI Light. HMI stands for Hydrargyrum Medium-arc Iodide. It is a direct current light source. Meaning it has a large ballast that plugs into a large electrical outlet that converts AC current (what we are used to using in our homes) to DC - direct current.
The result is a dramatic increase in wattage to light output and loss of light-energy through heat - 300-400% in efficiency.
A 4K HMI light is as powerful as a 10K Tungsten bulb light.
HMI's tend to shift more towards daylight temperature range. So this has to be compensated for.
And if you are not trained on how to use one - they are instantly deadly. You have to completely shut off the circuit and power to the ballast unit to unplug the light head. If you don't, you'll electrocute yourself - and not a small shock. It's the kind of power that stops your heart and doesn't allow you to be resuscitated.
This is why there are gaffers - specialists to handle electrically powered items - on movie sets. They've been trained to identify and manage these devices safely.