Camera system capable of interchanging its objective lens

In a camera system having a camera body and an interchangeable objective lens removably coupled with the camera body, the improvement which comprises:

• means, located in the camera body, for manually setting exposure time;
• means, located in the camera body, for manually setting aperture value;
• means, located in the camera body, for restricting the manual aperture value setting within an aperture value range;
• means, located in the camera body, for measuring light through the interchangeable objective lens with its aperture fully open;
• means, located in the camera body, for selecting one of manual, shutter priority, aperture priority and program exposure modes;
• means for retaining the manually set exposure time and the manually set aperture value regardless of a selection among the manual, shutter priority, aperture priority and program exposure modes;
• means, located in the camera body, for practicing an automatic exposure control calculation in one of the shutter priority, aperture priority and program exposure modes in response to at lest necessary one of the measuring means, the manually set exposure time and the manually set aperture value so that the calculated aperture value is restricted within the aperture value range;
• first means located in the camera body, for controlling the shutter speed in response to the manually set or calculated exposure time;
• second means, located in the camera body, for controlling the aperture size in response to the manually set or calculated aperture value;
• a common electric terminal located in the interchangeable lens;
• means, located in the interchangeable objective lens, for transmitting a first electric data representative of the fully open aperture size and a second electric data representative of the minimum available aperture size peculiar to the objective lens, through said common electric terminal to the camera body for the use in the restriction of manual aperture value setting in the camera body and for the use in the automatic exposure control calculation, and
• means, located in the interchangeable objective lens, for adjusting the aperture size always in response to the second controlling means in any one of the manual, shutter priority, aperture priority and program exposure modes without any source of manually controlling the adjusting means within the interchangeable objective lens.

In a camera system capable of a manual and an automatic exposure control having a camera body and an interchangeable objective lens removably coupled with the camera body, the interchangeable objective lens comprising:

• a camera electric terminal;
• means for transmitting a first electric data representative of the fully open aperture size and a second electric data representative of the minimum available aperture size peculiar to the objective lens, through said common electric terminal to the camera body for the use in a restriction of manual aperture value setting in the camera body within an aperture value range defined between the first and second electric data and for use in an automatic exposure control calculation in the camera body;
• means for transmitting a third electric data representative of the focal length of the interchangeable objective lens, through said common terminal to the camera body;
• means for transmitting a fourth electric data representative of an error in fully open aperture metering which is to be caused by using the interchangeable objective lens, through said common terminal, and
• means for adjusting the aperture size always under the control of the camera body in any one of the manual and automatic exposure control mode without any source of manually controlling the adjusting means within the interchangeable objective lens.

In a camera system capable of a manual and automatic exposure control having a camera body and an interchangeable objective lens removably coupled with the camera body, the interchangeable objective lens comprising:

• a common electric terminal;
• means for transmitting a first electric data representative of the fully open aperture size and a second electric data representative of the minimum available aperture size peculiar to the objective lens, through said common electric terminal to the camera body for use in a restriction of manual aperture value setting in the camera body within an aperture value range defined between the first and second electric data and for use in an automatic exposure control calculation in the camera body;
• means for transmitting a third electric data representative of the focal length of the interchangeable objective lens, through said common electric terminal to the camera body;
• means for transmitting a predetermined data common to all of the available interchangeable objective lenses in the system, through said common terminal to the camera body, and
• means for adjusting the aperture size always under the control of the camera body in any one of the manual and automatic exposure control modes without any source of manually controlling the adjusting means within the interchangeable objective lens.

In a camera system capable of a manual and automatic exposure having a camera body and an interchangeable objective lens removably coupled with the camera body, the improvement comprising:

• means, located in the interchangeable objective lens, for adjusting the aperture size of the lens without any source of manually controlling the adjusting means within the interchangeable objective lens;
• a common electric terminal for data transmission for the interchangeable objective lens to the camera body;
• means, located in the interchangeable objective lens, for transmitting a first electric data representative of the fully open aperture size and a second data representative of the minimum available aperture size peculiar to the objective lens, through said common electric terminal to the camera body;
• means, located in the interchangeable objective lens, for transmitting a third electric data representative of the focal length of the interchangeable objective lens through said common electric terminal to the camera body;
• means, located in the camera body, for measuring light through the interchangeable objective lens with its aperture kept fully open;
• means, located in the interchangeable objective lens, for transmitting a fourth electric data representative of an error in the fully open aperture light measurement which is inevitable depending on the interchangeable objective lens coupled with the camera body;
• means, located in the camera body, for selecting between the manual exposure control mode and a program exposure control mode in which both exposure time and the aperture size are automatically controlled;
• means, located in the camera body, for manually setting exposure time;
• means, located in the camera body, for manually setting aperture value;
• means, located in the camera body, for restricting the manual aperture value setting within an aperture value range defined between the first and second electrical data transmitted from the interchangeable objective lens;
• means, located in the camera body, for calculating both the exposure time and aperture value free from the fully open aperture light measurement error in the program exposure control mode in response to said measuring means and said first, second and fourth data so that the calculated aperture value is restricted within the aperture value range defined between the first and second electric data, said calculating means including a plurality of exposure programs and means for adopting one of the programs in response to said third electric data, the first and second electric data being effective to restrict the calculated aperture value regardless of the selection of the program;
• means, located in the camera body, for performing a calculation for the manual exposure control mode in response to said manual exposure time setting means and said manual aperture value setting means;
• a shutter means located in the camera body;
• first means, located in the camera body, for controlling said shutter means in response to the manually set or automatically calculated exposure time, and
• second means, located in the camera body, for controlling said adjusting means in response to the manually set or automatically calculated aperture value.