CBSE Class 12-science Answered

Huygens eyepieces consist of two plano-convex lenses with the plane sides towards the eye separated by an air gap. The lenses are called the eye lens and the field lens. It is usually designed for zero transverse chromatic aberration. The focal plane is located between the two lenses

comprises two plano convex lenses with the same focal length and glass, placed less than one focal length apart. The separation varies between different designs, but is typically somewhere between 7/10 and 7/8 of the focal length of the lenses, the choice being a trade off between residual transverse chromatic aberration (at low values) and at high values running the risk of the field lens touching the focal plane when used by an observer who works with a close virtual image such as a myopic observer,