Digital still camera

Abstract

Prior to a photographing operation, an image blur quantity indicating the extent to which the image becomes blurred during the photographing operation is calculated based upon an image-capturing sensitivity having been set, and a decision is made as to whether or not the image-capturing sensitivity needs to be adjusted based upon the calculated image blur quantity. If it is decided that the sensitivity level needs to be adjusted, the image-capturing sensitivity is adjusted and the photographing operation is executed at the shutter speed calculated based upon the adjusted image-capturing sensitivity.

What is claimed is:  
     
         1 . A digital still camera comprising: 
 a sensitivity setting device that sets an image-capturing sensitivity;    a photographing device having an image-capturing element that receives a light flux transmitted through a photographic lens and executes photoelectric conversion on the received light flux;    a control device that engages the photographing device in operation at a shutter speed corresponding to the image-capturing sensitivity set by the sensitivity setting device;    an image blur calculation device that calculates an image blur quantity indicating an extent to which an image becomes blurred during a photographing operation based upon the image-capturing sensitivity having been set prior to the photographing operation; and    a determination device that makes a decision as to whether the image-capturing sensitivity needs to be adjusted based upon the image blur quantity calculated by the image blur calculation device, wherein:    the sensitivity setting device adjusts the image-capturing sensitivity if the determination device determines that the image-capturing sensitivity needs to be adjusted; and    if the image-capturing sensitivity is adjusted, the control device engages the photographing device in operation at a shutter speed corresponding to the adjusted image-capturing sensitivity.    
     
     
         2 . A digital still camera according to  claim 1 , wherein: 
 if the calculated image blur quantity exceeds a predetermined limit value, the sensitivity setting device shifts the image-capturing sensitivity to a higher level so as to lower the image blur quantity to a value equal to or less than the limit value.    
     
     
         3 . A digital still camera according to  claim 1 , wherein: 
 the image blur calculation device includes a vibration detection sensor that detects an extent of vibration to which the digital camera is subjected, and calculates the image blur quantity indicating the extent to which the image becomes blurred during the photographing operation based upon detection results provided by the vibration detection sensor and the shutter speed determined in conformance to photometering results obtained by photometering a photographic field and the image-capturing sensitivity having been set.    
     
     
         4 . A digital still camera according to  claim 3 , further comprising: 
 an optical image blur correction mechanism that reduces the extent of image blur based upon an output from the vibration detection sensor, wherein;    the determination device determines that the image-capturing sensitivity needs to be adjusted if the image blur quantity cannot be lowered to a value equal to or less than a predetermined limit value through an image blur correction alone executed by the optical image blur correction mechanism.    
     
     
         5 . A digital still camera according to  claim 1 , wherein: 
 the sensitivity setting device sets the image-capturing sensitivity to a lowest possible sensitivity level within a range over which the calculated image blur quantity does not exceed a predetermined limit value.    
     
     
         6 . A digital still camera according to  claim 2 , wherein: 
 the image blur calculation device includes a vibration detection sensor that detects an extent of vibration to which the digital camera is subjected, and calculates the image blur quantity indicating the extent to which the image becomes blurred during the photographing operation based upon detection results provided by the vibration detection sensor and the shutter speed determined in conformance to photometering results obtained by photometering a photographic field and the image-capturing sensitivity having been set.    
     
     
         7 . A digital still camera according to  claim 6 , further comprising: 
 an optical image blur correction mechanism that reduces the extent of image blur based upon an output from the vibration detection sensor, wherein:    the determination device determines that the image-capturing sensitivity level needs to be adjusted if the image blur quantity cannot be lowered to a value equal to or less than the limit value through an image blur correction alone executed by the optical image blur correction mechanism.    
     
     
         8 . An image blur correction apparatus comprising: 
 a sensitivity setting device that sets an image-capturing sensitivity;    an image capturing command output device that outputs a signal for engaging an image-capturing element in photoelectric conversion at a shutter speed corresponding to the image-capturing sensitivity set by the sensitivity setting device;    an image blur calculation device that calculates an image blur quantity indicating an extent to which an image becomes blurred during a photographing operation based upon the image-capturing sensitivity having been set, prior to the photographing operation; and    a determination device that makes a decision as to whether the image-capturing sensitivity needs to be adjusted based upon the image blur quantity calculated by the image blur calculation device, wherein:    the sensitivity setting device adjusts the image-capturing sensitivity if the determination device determines that the image-capturing sensitivity needs to be adjusted; and    when the image-capturing sensitivity is adjusted, the image capturing command output device outputs the signal to the image-capturing element to engage the image-capturing element in photoelectric conversion at the shutter speed corresponding to the adjusted image-capturing sensitivity.    
     
     
         9 . An image blur correction apparatus according to  claim 8 , further comprising: 
 a blur preventing mode switch operated to set/clear a blur preventing mode in which control is implemented to reduce the extent of image blur by adjusting the image-capturing sensitivity.