Q: What are the "beehive" and "beam tube" in photographic equipment used for?

Beehives are used to produce parallel light, which can produce shadows with clear boundaries. A point light source can create a shadow with a clear boundary, and a parallel light is a point light source at infinity. )

Beam barrel is used to reduce the irradiation area of light source and distribute light locally.

The combination of the two can produce shadows with clear local boundaries.