Field of the Invention
The present invention relates to a lens apparatus appropriate for, for example, a video camera, a digital still camera, and a TV camera, each having the function of performing close distance photography at approximately 1:1 magnification, and also relates to an image pickup apparatus including such a lens apparatus.
Description of the Related Art
A known image pickup optical system mainly for close distance photography is a macro lens. In general, close distance photography has a small distance from an object to an image pickup optical system, and thus, the image pickup optical system or a photographer can cast shadow over the object side in some cases. To prevent this, lighting is often needed in close distance photography. As a conventional illumination light source for image pickup, a flash light emission using a xenon lamp is used. Since the flash light emission using a xenon lamp is an instantaneous pulse light emission, however, there arises a problem that an illuminated object image cannot be seen through a finder or the like.
In such situations, light emitting diodes having a wide wavelength band in a visible range have been put into practical use in recent years. Japanese Patent Application Laid-Open No. 2006-337422 and Japanese Patent Application Laid-Open No. 2011-247978 describe illumination apparatuses in each of which a light emitting diode is disposed on a holding frame that holds a lens closest to an object side in an image pickup optical system to illuminate the object side.
Japanese Patent Application Laid-Open No. 2006-337422 describes an illumination apparatus in which a plurality of white light emitting diodes are arranged in an annular shape on an outer peripheral portion of the holding frame that holds the lens disposed closest to an object side. Japanese Patent Application Laid-Open No. 2011-247978 describes an illumination apparatus using a light guide part in which an optical path through which light propagates is formed in an annular shape. Japanese Patent Application Laid-Open No. 2011-247978 also describes that the amount of light applied from the illumination apparatus is changed by changing the location of a light source in an optical axis direction.
In the illumination apparatus described in Japanese Patent Application Laid-Open No. 2006-337422, each light source is disposed to have a light emission plane of the light source oriented in the optical axis direction of the image pickup apparatus. Thus, to uniformly illuminate an object, a large number of light sources are needed.
In the illumination apparatus described in Japanese Patent Application Laid-Open No. 2011-247978, a short distance between two light sources makes it difficult to uniformly illuminate an object.
USPTO Backgrounds
USPTO Backgrounds