Aperture-priority lens shutter apparatus for a camera

An aperture-priority lens shutter apparatus for a camera comprising:

• a lens mount including a hollow cylindrical portion defining an opening and a flange fixed on said cylindrical portion;
• at least two sheet-like lens shutter blades rotatably mounted on said flange of the lens mount on a side opposite said cylindrical portion to cover over the opening, and of which an open degree is decided in accordance with an F number and of which an open time is decided in accordance with an exposure time;
• a first means for driving the lens shutter blades;
• a second means for setting the F number manually;
• a light measuring means for producing a signal corresponding to the amount of light available to photograph an object;
• and
• a central processing unit including an exposure control time table in which the F number for exposure in a suitable exposure value in accordance with the measured value by said light measuring means and exposure time data are inputted, an operator which recognizes the F number set manually in a semiautomatic mode, receives the data from the exposure control time table corresponding to a signal from said light measuring means, calculates a time for maintaining the exposure state in the set F number, adds the exposure time from the exposure control time table to the time for maintaining the exposure state and calculating a total exposure time, and a driver for driving the first means in accordance with a result from the operator.