In most photography and all telescopy, where the subject is essentially infinitely far away, longer focal length (lower optical power) leads to higher magnification and a narrower angle of view conversely, shorter focal length or higher optical power is associated with lower magnification and a wider angle of view. For more general optical systems, the focal length has no intuitive meaning it is simply the inverse of the system's optical power. For the special case of a thin lens in air, a positive focal length is the distance over which initially collimated (parallel) rays are brought to a focus, or alternatively a negative focal length indicates how far in front of the lens a point source must be located to form a collimated beam. A system with a shorter focal length bends the rays more sharply, bringing them to a focus in a shorter distance or diverging them more quickly. A positive focal length indicates that a system converges light, while a negative focal length indicates that the system diverges light. The focal length of an optical system is a measure of how strongly the system converges or diverges light it is the inverse of the system's optical power. The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |