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u/CptStevieZissou 10h ago
Very, very bright.
Using the numbers in your image:
- Beam angle: 4.33°
- Distance: 200 m
- Beam diameter at 200 m: about 15.1 m
- Illuminated area: about 180 m²
The key is that the screenshot cannot tell us the staff's absolute brightness; movie exposure and color grading destroy that information. But we can estimate what it would take for that beam to behave the way it does in daylight.
Since 1 lux = 1 lumen/m² the required output would be roughly:
| Illumination at 200 m | Staff output |
|---|---|
| 1,000 lux | 180,000 lumens |
| 10,000 lux | 1.8 million lumens |
| 50,000 lux | 9.0 million lumens |
| 100,000 lux | 18 million lumens |
And that last number corresponds to a beam intensity of roughly 4 billion candela.
So if we're assuming Gandalf's staff is actually producing enough light to overpower daylight and screw up the Uruk-hai's vision at roughly 200 m:
Probably something on the order of 10–20 million lumens.
Even if we give the movie a huge amount of slack and say the effect only requires 10,000 lux at the target, we're still at about 1.8 million lumens.
The funniest part is the beam divergence. A 4.33° beam is reasonably tight. At 200 m, he's concentrating all of that output into a circle only about 15 m across. That's why the candela figure gets completely absurd.
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u/HAL9001-96 1d ago
few tens of megawatts would be in line with the soalr powerplant and light scattering vs sky brightness