Umbrellas are used not only blocking the rain. If we err umbrella we can use to hit the pickpocket by, but the situation was rare.
Then ask the photographer what other functions besides an umbrella, holding the blazing heat, and rainfall. They will answer immediately that the umbrella is useful for the installation of photographic images. Especially helpful flashbulbs from photographers, and also helpful for the function of the arrangement of lighting lamps.
The inside of the umbrella will absorb, casting, refract the light back blitz, and the light of the rules of other lamps, produce a more equitable ekposure to the object to be photographed