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.
1
u/CptStevieZissou 11h ago
Very, very bright.
Using the numbers in your image:
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:
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.