Set of negative meniscus lenses, wide-angle optical system, image pickup apparatus, and projection apparatus

A set of negative meniscus lenses, comprising:

• a first meniscus lens;
• and
• a second meniscus lens;
• wherein
• the set of negative meniscus lenses has a predetermined lens surface,
• the set of negative meniscus lenses is used for an optical system having an angle of view not smaller than 240°,
• one negative meniscus lens in the set of negative meniscus lenses is located nearest to an object,
• the predetermined lens surface is a hemispherical surface or a surface extending beyond hemisphere,
• the first meniscus lens and the second meniscus lens are adjacent, and
• both the first meniscus lens and the second meniscus lens are meniscus lenses having a convex surface directed toward an object side.