| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter device for observing the sun, capable of achieving a stable light shielding property at low cost.SOLUTION: The filter device for observing the sun, which can be attached to an object side of a lens barrel or a finder of a telescope includes: a cylindrical housing 1; and an absorption type filter part 2 stored in the housing 1. The filter part 2 includes two glass filters 2A, 2B. Transmittance at a near-infrared region, of each of the filters 2A, 2B is 0.5 percent or less. In a state where the two filters 2A, 2B are overlapped with each other, transmittance at a visible region is 0.003 percent or less. |
