There is no direct conversion between candlepower and lumens because they measure different things.
Candlepower, also known as candelas, is a measure of the intensity of light in a particular direction, while lumens measure the total amount of visible light emitted by a source in all directions.
The relationship between the two units depends on the angle of the light source. To convert lumens to candlepower for a specific angle, you would need to use the formula:
Candlepower = Lumens / (Solid Angle in Steradians)
The solid angle is a measure of the size of the cone of light emitted by the source, with 1 steradian being the solid angle of a cone that encloses one unit of area on a sphere with a radius of one unit.
For example, if a flashlight emits 500 lumens of light in a beam with a solid angle of 0.1 steradians, the candlepower of the flashlight in that direction would be:
Candlepower = 500 lumens / 0.1 steradians = 5000 candelas
However, if the flashlight emits the same 500 lumens of light in all directions, the candlepower would be different depending on the angle of measurement. In this case, you would need to measure the intensity of the light at a specific angle to calculate the candlepower.
So, the answer to the question “how much candlepower is in a lumen?” depends on the angle of the light source and the solid angle of the measurement.