| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the hunting phenomenon of a stop blade in closeup photography, etc., by stabilizing the variation rate of the quantity of lighting to the operation quantity of the stop blade. SOLUTION: This device includes a gate part 14, where a noncircular opening 13 varying the quantity of the light of a light source linearly is formed, one stop base 15, which stops down the passing light of the noncircular opening 13 of the gate part 14, and a motor 16 for driving the stop blade 15, V-shaped parts 13A and 13B in two stages are provided as the noncirualr opening 13, and an auxiliary opening 20, which passes part of the light is formed in the said stop bade 15. Variation in the quantity of output light with the operation quantity of the stop blade becomes linear even in an area, wherein the quantity of light is reduced small because of the V-shaped parts 13A and 13B and auxiliary opening 20 to prevent the hunting phenomenon. |
