| 摘要 |
The purpose of the present invention is to provide an imaging optical system that has a small F number less than or equal to 1.1, is equipped with a bandpass filter having a half bandwidth less than or equal to ±100 nanometers, and is capable of preventing a decrease in the transmittance of the bandpass filter. The imaging optical system according to the present invention comprises, in order from the object side toward the image side: a first lens which is a negative lens; a second lens which is a meniscus lens with a convex surface facing the image side; a diaphragm; two or more lenses between the diaphragm and the image surface, including at least one positive lens. The imaging optical system further comprises a bandpass filter having a half bandwidth less than or equal to ±100 nanometers, provided adjacent to the diaphragm on the object side or the image side. The F number thereof is less than or equal to 1.1. |
