I don't understand, if those lights are so powerful then how do actors survive under their light?
One thing I learned while webcasting Yves St. Laurent's fashion show in the mid 90's is that the flowers wilt within minutes of being placed due to all of the heat from the lights. So the way they dealt with that is that backstage there is an absolutely enormous amount of flowers ready to be deployed and they just cycle through flower arrangements continuously for the duration of the show so that the flowers are always fresh. It's tens of people walking to and fro without pause.
https://en.wikipedia.org/wiki/The_Thin_Man_(film)#Filming
(Great movie BTW!)
As to the number of takes and food: one particular set I recall was for a cookie brand, they did endless re-takes and the actress that had to eat the cookies started to get sick enough to vomit. We were all pretty happy when the director was finally satisfied with what must have been his masterpiece.
Second, these weren't ordinary stage lights. These were lights for use outdoors to simulate natural sunlight, which is much brighter (and hotter) than what you'd normally use indoors.
Third, they were probably positioned too close, and left on for too long. Just a guess on this one.
Maybe this kind of foam isn't entirely up to the spec either.
It’s an surmountable problem, but can be expensive if it doesn’t need to be overcome often.
(All speculation on my part)
I've become much less of a fan of the "switchilinear" approach. The control loop of a linear regulator isn't fast enough to respond to fast switching frequencies; the regulator is effectively just a resistor in a filter network at that point.
Even if your switching frequency is in the regulator's loop bandwidth, the loop's gain at that frequency is almost certainly very low.
Assuming you're using a global shutter camera: even if the ripple is completely unfiltered, the only remaining intensity effect would be that some frames get 8000 "blinks" in a frame and some get 8001.
Already, stage and film lighting is a relatively small market compared to the entire lighting market, but it's not so small that NRE can't be spread across a lot of units.
I believe the time constant for most small lamps is 30ms and longer for bigger lamps. 1 / (2 * pi * 30ms) is 5Hz, so 120 Hz will be about 30 dB down. This is probably just barely big enough to matter.
I wonder what the filament looks like.
E.g. I have both fluorescent and HID lamps with this characteristic; they take a couple minutes to reach full brightness, but still will dim when a big load kicks on and turn off immediately when I flip the switch.
Is the limiting factor the technology to make a 4500W LED bulb in the same form-factor/focus as the 18kW halogen, or does it just become prohibitively expensive to do so?
https://en.wikipedia.org/wiki/Color_rendering_index#Film_and...
But otherwise yes they would be less hot.
Light is energy, and filming requires a lot of light, so there's always going to be significant visible energy available to heat things up. (Unless you're filming a mirror, but in that case why are you illuminating it?)
Incandescent lights emit a lot of invisible energy in the form of infrared radiation, while LEDs are designed to emit most of their energy in the visible spectrum. This means LEDs need less energy to produce the same visual effect, and therefore impart less heat. Another option is to slap a "hot mirror" or "cold mirror" (like the one from the dentist's office) in front of your lights that separates the visible from IR.
Cold mirrors that large are expensive and it's just complexity/something to break or need servicing (cleaning) so I doubt they were stocked much by rental companies or saw much usage in tv/movie production.
Spotlights like these though, you might as well be holding a giant magnifying glass. The beam is culminated and will cook whatever it’s pointing at. Will it cook a human? Yes if you stand there, still, for long enough. You will definitely get sun burned. If you get within 10 feet it will feel like your standing in an oven. Within 5 feet and your skin could boil.