How many lumens is the brightness of the photographic flash?

Flash is measured by an index, not by lumens, but if you have to use lumens as a unit, you can convert it.

Take the 32-finger flash as an example:

When the illumination is 40000 lux, the exposure of the aperture 4 is11000 seconds, which is about ISO 100.

If the flash with index 32 uses ISO 100 aperture 4 within1000, the distance is 32/4 = 8m.

The shooting area of 8 meters under a 35mm lens is 62 square meters.

Therefore, the instantaneous luminous flux of a flash lamp with an index of 32 is 40,000 lux * 62 m2 = the instantaneous brightness is 2.5 million lumens.

(PS: 1 is the theoretical calculation result; 2 Different calculation methods may result in slightly different results. )