Exposure control system for a single lens reflex camera with an interchangeable objective lens

Claim 2

A single lens reflex camera, comprising, a camera body, a plurality of objective lenses of different focal lengths interchangeably mountable on said camera body, a light measuring system mounted in the camera body, said light measuring system including a plurality of electro-photosensitive elements exposed to light traversing an objective lens mounted on said camera body, said elements being positioned to sense the light from different local areas of the total light passing through the objective lens, compensating means fixed on each of said objective lenses, said compensating means each corresponding to one of said elements, said light measuring system including an operating circuit and detecting means responsive to said compensating means for connecting the corresponding one of said elements to said circuit.

Claim 3

A camera as in claim 1, wherein said circuit includes an ammeter responsive to light incident on the connected one of said elements.

Claim 4

A camera as in claim 2, wherein said circuit includes maximum-aperture responsive means for also varying the current through the ammeter in response to the maximum apertures of said objective lenses, said objective lenses each including setting means coupled to said maximum-aperture responsive means for transmitting the maximum-aperture of the objective lens to said responsive means.

Claim 5

A camera as in claim 3, wherein said detecting means includes a leaf switch.

Claim 6

A camera as in claim 1, wherein the number of said elements is at least equal to three, the first of said elements being positioned to receive approximately the center area of the light through the objective lens mounted on the camera, said second one of said lenses being positioned to receive approximately an upper area of light through the lens, a third one of said elements being positioned to receive approximately a lower area of light through the lens.

Claim 7

A camera as in claim 5, wherein said detecting means includes a leaf switch for connecting the corresponding one of said elements on the basis of said compensating means.

Claim 8

A camera as in claim 6, wherein the compensating means which connects the second of said elements to the circuit is on a wide angle lens and the compensating means which connects the third of said elements is on a wide angle lens.

Claim 9

An exposure control system as in claim 6, wherein said exposure determining means further includes at least one photoconductor to receive light through the mounted lens and said variable resistive means include electrode means for short circuiting said sliders and connecting the photoconductor with said power source.

Claim 10

A system as in claim 8, wherein said exposure determining system further includes a timer device mountable on the camera body and having an input terminal with said means for short circuiting the sliders and the photoconductor as well as the power source.

Claim 11

A camera as in Claim 5, wherein the detecting means connects the corresponding one of said elements together with a least one other one of said elements.

Claim 12

A camera as in claim 10, wherein said detecting means connects the second of said elements with the corresponding one of said first and third elements

Claim 13

A camera as in claim 10 wherein the number of elements is four and said detecting means connects the fourth and second of said elements together with the corresponding of the first and third of said elements.

Claim 14

A camera as in claim 1, wherein said detecting means includes a leaf switch for connecting one of the elements, and said circuit means includes an ammeter responsive to the light incident on the element connected by said switch to said circuit.

Claim 15

A camera as in claim 1, wherein said circuit includes a voltage source and said light responsive elements include photo-conductive transducers.

Claim 16

A camera as in claim , 1 wherein said light measuring system includes a power source, an ammeter for indicating exposure conditions connectable with said power source, variable resistive means connected with said ammeter and said power source, engagement means for engaging the focusing ring on the lens when it is mounted to said variable resistive means, said resistive means including a plurality of resistors each having a terminal, said variable resistive means including a pair of sliders for sliding from terminal to terminal, the spacing between the sliders corresponding to the difference of the rotating angle of the mounted lens.

Claim 17

A system as in claim 15, wherein said exposure determining system further includes an actuating switch connected in series with said power source and said ammeter and capable of being switched on and off, and engageable means having an engaging member operably mounted and associated with the actuating switch to turn it on only when it engages the focusing ring.

Claim 18

A camera as in claim 16, wherein said switching means includes a leaf switch member operatively connected with said projection means fixed on said lens and having an initial position, said projection means having two different lengths in accordance with the focal length and maximum operature value of said lens, said circuit having first and second fixed electrodes one of which is connected with said first element and the other of which is connected with said second element and the leaf switch member in its initial position, said first electrode being connected with said leaf switch member through the projection member of said telephoto lens and said second electrode being disconnected from said leaf switch member through the projection means of the standard lens.

Claim 19

An exposure control system as in claim 15, wherein said exposure determining system includes diaphragm means for said objective lens, said diaphragm means being adjustable by said ammeter.

Claim 20

A camera as in claim 15, wherein said compensating means on each lens includes a projection fixed on each lens, the projection a wide angle lens having a different length from the projection on a telephoto lens.

Claim 21

A camera as in claim 15, wherein said switching means includes on a leaf switch for connecting one of said first and second elements together with said third element with said galvanometer.

Claim 22

A camera as in claim 15 wherein said operating circuit includes a voltage source and said electro-photosensitive elements are photoconductive transducers.

Claim 23

A single lens reflex camera, comprising: a camera body, a plurality of objective lenses of different focal lengths interchangeably mountable on said camera body, a light measuring system mounted in the camera body, said light measuring system including a plurality of electro-photosensitive elements exposed to light traversing an objective lens mounted on said camera body; said elements being positioned to sense the light from different local areas of the total light passing through the objective lens, a first of said elements being Positioned in the camera body to receive light from an upper vertical portion of a subject, a second element positioned in the camera body to receive light from a lower vertical portion of a subject and a third element positioned in the camera body to receive light from a center vertical portion of a subject, an operating circuit including exposure indicating means having a galvanometer connected in said operating circuit, switching means selectively connecting said third element and one of other elements, with said galvanometer, and compensating means fixed on each of said lenses and operatively connected with said switching means for switching said switching means according to the focal length and maximum operature value of each lens mounted on the camera body, the compensating means on a wide angle objective lens of said lenses switching said switching means so that said galvanometer is actuated substantially by said second element, the compensating means on a telephoto objective lens of said lenses switching the switching means so the galvanometer is acuated substantially by said first element.

Claim 24

A single lens reflex camera, comprising: a camera body, a plurality of objective lenses of different focal lengths interchangeably mountable on said camera body, a light measuring system mounted in the camera body, said light measuring system including a plurality of electro-photosensitive elements exposed to light traversing an objective lens mounted on said camera body; said elements being positioned to sense the light from different local areas of the total light passing through the objective lens, a first of said elements being Positioned in the camera body to receive light from an upper vertical portion of a subject, a second element positioned in the camera body to receive light from a lower vertical portion of a subject and a third element positioned in the camera body to receive light from a center vertical portion of a subject, an operating circuit including exposure indicating means having a galvanometer connected in said operating circuit, switching means selectively connecting said third element and one of other elements, with said galvanometer, and compensating means fixed on each of said lenses and operatively connected with said switching means for switching said switching means according to the focal length and maximum operature value of each lens mounted on the camera body, the compensating means on a wide angle objective lens of said lenses switching said switching means so that said galvanometer is actuated substantially by said second element, the compensating means on a telephoto objective lens of said lenses switching the switching means so the galvanometer is acuated substantially by said first element.