Do cheap-ish lights for slow motion exist?

[Michael Carter]

Well, I wasn't suggesting that the entire thing be lit with one 150W light, but they're cheap enough to rank up.

Hey, I love my 150's. A 3" HID fresnel is a handy thing to have. I even have several of those alzo 150 fixtures that take Bowens accessories, and two of their bulb and ballast combos that work for practicals and china balls. Well, when they work, sometimes they're like "naah, not today".

 

[Grug]

For 240fps work I've been able to get away with 2kw Blondes and 650w Dedolights - and lights don't come much cheaper than those to rent. It's really more the 500-1500fps range that you run into serious issues with light.

 

[ReelFilmGeek]

What about tungsten lamps? A Mole Baby Jr 2K fresnel probably won't flicker much, if at all, considering the large filament. The general rule is that the larger the filament, the less prone to flicker it is, since it takes longer for the lamp to cool down. Beyond that, crystal sync HMIs should work, since 240 is just a multiple of 24. There's also LEDs from Aadyn, Arri, Mole, and Cineo to consider.

Tungsten is the cheapest, HMIs are more, and quality LEDs (that don't flicker) are even more expensive. You can typically rent tungsten lamps for cheap, and find them used inexpensively, too.

So would that be the reason why my 650 and 300 watt fresnels were causing flickering when I was shooting slow motion with the FS5? Example seen here (haven't got to edit yet since it was a experiment and I've been busy so its just a bunch of slow mo clips)

https://www.youtube.com/watch?v=KOVvpsO_qkA

 

[Mitch Gross]

AC power is short for Alternating Current, which means that the power coming through the line is switching polarity in cycles of either 50 times or 60 times per second (depending on the country you live in). The power frequency is a sine wave, with full power at the top in one direction and full power at the bottom in the opposing direction and zero power in the middle. The power goes up and down either way 50 or 60 times each second for a total of 100 or 120 cycles every second (how many peaks and valleys). So for all those times the power is full blast in one direction or the other, it also has to pass through zero juice to get from one end to the other. 50 or 60 times each second the lamp is receiving no power at all.

On a small wattage bulb, when the power goes away the bulb begins to cool and dim. Then the power comes back up and the light regains brightness. This happens so fast that you don't notice it, but when you shoot high speed and then play it back in slow motion the process becomes quite apparent. The reason higher wattage bulbs don't flicker is that the filament is so crazy freaking hot that it simply doesn't have time to cool off and dim noticeably before the next wave of power comes along.

Compare all this to DC power, direct current. That's just continuous power always feeding in. No flicker at all. DC power is great for batteries and simple circuits, but it doesn't travel well very far. AC power is better for long distance and power grid systems.

An aside -- DC power was Edison and AC power was Tesla & Westinghouse. Edison didn't actually understand AC power at first, and tried to scare people away from it by portraying it as unsafe. He's the reason the Electric Chair was invented, because he wanted to show how dangerous AC power could be. Of course it was nonsense and either one could be just as dangerous, and eventually AC power won out as the logical way to run power lines throughout cities and eventually the world. DC is only good for extremely local power, like in a single device or even a car.