Image surface illuminance varying apparatus, exposure correcting apparatus, and exposure correcting method

Abstract

An image surface illuminance varying apparatus includes a variable power optical system in which the optical power thereof can be varied by changing a relative position of a plurality of optical elements thereof; and a light-quantity ratio varying optical element whose transmittance varies in a direction perpendicular to an optical axis of the variable power optical system, the light-quantity ratio varying optical element being located in a light path of the variable power optical system to reduce an illuminance difference of an imaging surface. A distance from the light-quantity ratio varying optical element, which is moved along the optical axis, to a diaphragm or a shutter is varied in accordance with the power varying operation.

1 . An image surface illuminance varying apparatus comprising: 
 a variable power optical system in which the optical power thereof can be varied by changing a relative position of a plurality of optical elements thereof; and    a light-quantity ratio varying optical element whose transmittance varies in a direction perpendicular to an optical axis of the variable power optical system, said light-quantity ratio varying optical element being located in a light path of the variable power optical system to reduce an illuminance difference of an imaging surface,    wherein a distance from the light-quantity ratio varying optical element, which is moved along the optical axis, to a diaphragm or a shutter is varied in accordance with the power varying operation.    
   
   
       2 . The image surface illuminance varying apparatus according to  claim 1 , wherein the light-quantity ratio varying optical element has a transmittance which is increased in a radial direction perpendicular to the optical axis.  
   
   
       3 . The image surface illuminance varying apparatus according to  claim 1 , wherein the light-quantity ratio varying optical element is moved toward said diaphragm or shutter when said optical power is varied toward the long focal length side, and the light-quantity ratio varying optical element is moved away from said diaphragm or shutter when said optical power is varied toward the short focal length side, in association with the power varying operation of said variable power optical system.  
   
   
       4 . The image surface illuminance varying apparatus according to  claim 1 , wherein said light-quantity varying optical element is moved together with an optical element located in front of said diaphragm or shutter in accordance with the power varying operation, and wherein said optical element in which the light-quantity ratio varying optical element is provided is moved along a moving path different from that of an optical element which is moved together with said diaphragm or shutter.  
   
   
       5 . The image surface illuminance varying apparatus according to  claim 1 , wherein said light-quantity ratio varying optical element comprises one lens element of a plurality of lens elements which constitute said variable power optical system.  
   
   
       6 . The image surface illuminance varying apparatus according to  claim 1 , wherein an object light bundle which passes through said variable power optical system and forms a central image is transmitted through a paraxial area of said light quantity varying optical element, and an object light bundle which passes through said variable power optical system and forms a peripheral image is transmitted through the peripheral area of said light-quantity ratio varying optical element; and 
 wherein said object light bundle forming said peripheral image is transmitted through a peripheral area far away from the paraxial area on the short focal length side and through a peripheral area close to the paraxial area on the long focal length side, respectively.    
   
   
       7 . An exposure correcting apparatus for a photographing apparatus comprising: 
 a photometer;    an optical element whose transmittance varies depending on the position at which light is transmitted therethrough, provided in a photographing optical system;    a diaphragm; and    a controller that corrects an exposure;    wherein said controller determines an appropriate exposure based on a photometering measurement of said photometer to set a control diaphragm value, wherein the appropriate exposure is obtained in accordance with the quantity of light transmitted through said optical element which is moved in accordance with the set said control diaphragm value.    
   
   
       8 . The exposure correcting apparatus according to  claim 7 , wherein an amount of exposure correction corresponding to said control diaphragm value is predetermined and stored in a memory.  
   
   
       9 . The exposure correcting apparatus according to  claim 7 , wherein said photographing apparatus is provided in a camera body having a detachable photographing lens, and an amount of exposure correction corresponding to the control diaphragm value is predetermined and stored in a memory provided in the photographing lens.  
   
   
       10 . An exposure correcting apparatus for a photographing apparatus comprising: 
 a zoom lens with an optical element whose transmittance varies depending on the position at which light is transmitted therethrough; and    a controller for correcting an exposure in accordance with a quality of light transmitted through said optical element which is moved in accordance with a change in a focal length of said zoom lens.    
   
   
       11 . The exposure correcting apparatus according to  claim 10 , wherein an amount of exposure correction corresponding to the focal length is predetermined and stored in a memory.  
   
   
       12 . The exposure correcting apparatus according to  claim 10 , wherein said photographing apparatus is provided in a camera body to which said zoom lens is detachably attached, and wherein an amount of said exposure correction corresponding to the focal length is predetermined and stored in a memory provided in said zoom lens.  
   
   
       13 . An exposure correcting apparatus for a photographing apparatus comprising: 
 a photometer;    a zoom lens having an optical element whose transmittance varies depending on the position at which light is transmitted therethrough, provided in a photographing optical system of said photographing apparatus; and    a controller for correcting an exposure so that an appropriate exposure is obtained in accordance with a quantity of light transmitted through said optical element which is moved in accordance with a control diaphragm value set based on a photometering measurement by said photometer and the quantity of light transmitted through said optical element which is moved in accordance with a change in a focal length of said zoom lens.    
   
   
       14 . The exposure correcting apparatus according to  claim 7 , wherein an amount of exposure correction corresponding to a focal length of said photographing optical system and an amount of exposure correction corresponding to the control diaphragm value are predetermined and stored in a memory.  
   
   
       15 . The exposure correcting apparatus according to  claim 13 , wherein said photographing apparatus is provided in a camera body to which said zoom lens is detachably attached, and wherein an amount of exposure correction corresponding to the focal length and an amount of exposure correction corresponding to the control diaphragm value are predetermined and stored in a memory provided in said zoom lens.  
   
   
       16 . The exposure correcting apparatus according to  claim 7 , wherein when the exposure is corrected, a shutter speed is controlled without correcting said control diaphragm value.  
   
   
       17 . The exposure correcting apparatus according to  claim 7 , wherein said photographing optical system comprises a variable power optical system in which the optical power thereof can be varied, and wherein said optical element comprises a light-quantity ratio varying optical element whose transmittance varies in a direction perpendicular to an optical axis of said variable power optical system, said light-quantity ratio varying optical element being located in the light path of said variable power optical system and varies a distance from a diaphragm or a shutter which is moved along the optical axis in accordance with the power varying operation.  
   
   
       18 . The exposure correcting apparatus according to  claim 10 , wherein the zoom lens comprises a variable power optical system in which the optical power can be varied by changing a relative position of a plurality of optical elements; 
 wherein said optical element comprises a light-quantity ratio varying optical element whose transmittance varies in a direction perpendicular to an optical axis of the variable power optical system, said light-quantity ratio varying optical element being located in an optical element which is provided in the light path of said variable power optical system and which varies a distance from a diaphragm or a shutter which is moved along the optical axis in accordance with the power varying operation.    
   
   
       19 . An exposure correcting method for a photographing apparatus having a photometer, an optical element whose transmittance varies depending on the position at which light is transmitted therethrough, provided in a photographing optical system, and a diaphragm, comprising: 
 determining an appropriate exposure based on the photometering measurement of said photometer to thereby set a control diaphragm value; and    correcting an exposure so that said appropriate exposure is obtained in accordance with the quantity of light transmitted through the optical element which is moved in accordance with the set said control diaphragm value.    
   
   
       20 . An exposure correcting method for a photographing apparatus having a photometer and a zoom lens having an optical element whose transmittance varies depending on the position at which light is transmitted therethrough, provided in a photographing optical system, comprising: 
 correcting an exposure in accordance with a quantity of light transmitted through said optical element which is moved in accordance with a change in a focal length of said zoom lens.    
   
   
       21 . An exposure correcting method for a photographing apparatus having a photometer, and a zoom lens having an optical element whose transmittance varies depending on the position at which light is transmitted therethrough, provided in a photographing optical system, comprising: 
 correcting an exposure so that an appropriate exposure is obtained in accordance with a quantity of light transmitted through the optical element which is moved in accordance with the control diaphragm value set based on a photometering measurement of said photometer, and the quantity of light transmitted through the optical element which is moved in accordance with a change in a focal length of said zoom lens.