a first embodiment of the present invention will be described with reference to fig5 . in fig5 the same members as those of fig4 are denoted by the same reference numerals . according to the figure , the display member 32 is situated lower than that of the conventional arrangement ( see fig4 ), and the light interrupting wing 6 b is disposed above the display member 32 . when the field frame is switched , the light interrupting wing 6 b interrupts the luminous flux b from the backlight 33 , so that information is not displayed in the finder . however , the time during which the luminous flux b is interrupted is extremely short and when the field frame switching is finished , information is displayed in the finder since the luminous flux b from the backlight 33 is not interrupted . thus , photographing can be performed without any problem . as described above , by disposing the light interrupting wing 6 b in a position that temporarily interrupts the luminous flux b from the backlight 33 , the space l 4 in the rear of the focusing screen 4 on the optical path of the luminous flux a from the subject can be reduced compared to the conventional arrangement ( see fig4 ). the light interrupting wings 6 a and 6 b of the above - described first embodiment can be driven , for example , by a mechanism as shown in fig6 a and 6b . fig6 a and 6b show a drive mechanism 60 provided at one end , along the length , of the light interrupting wings 6 a and 6 b . according to fig6 a , a focusing screen holder 62 for holding the focusing screen 4 so as to be positioned has two rotary members 64 and 65 integrated with rotation axes 64 a and 65 a and rotatable about the rotation axes 64 a and 65 a . the rotation axes 64 a and 65 a pass through the focusing screen holder 62 to be also integrated with the light interrupting wings 6 a and 6 b . the rotary members 64 and 65 have drive pins 66 and 67 . the light interrupting wings 6 a and 6 b are rotated by the rotation of the drive pins 66 and 67 . the focusing screen holder 62 also has a drive lever 63 being rotatable about a rotation center 63 c and engaging with an operation lever 61 that rotates about a rotation center 61 a . the drive lever 63 has guide grooves 63 a and 63 b for guiding the drive pins 66 and 67 . a return spring 68 engages with the drive lever 63 so that the drive lever 63 receives a force in the clockwise direction of the figure . when the operation lever 61 is rotated in the direction of the arrow e 1 , the drive lever 63 engaging with the operation lever 61 rotates in the counterclockwise direction , so that the drive pins 66 and 67 being guided by the guide grooves 63 a and 63 b are rotated in the directions of the arrows d 1 and d 2 . this moves the light interrupting wings 6 a and 6 b to the positions shown in fig6 b . under this condition , the operation lever 61 can be held at the position shown in fig6 b by a holding mechanism ( not shown ) such as a click mechanism . when the operation lever 61 is rotated from the position shown in fig6 b in the direction of the arrow e 2 , the drive lever 63 is rotated in the clockwise direction by the return spring 68 . this moves the light interrupting wings 6 a and 6 b to the positions shown in fig6 a . in the light interrupting wings 6 a and 6 b , arms 6 a 2 and 6 b 2 formed only on both ends , along the length , of wings 6 a 1 and 6 b 2 hold the wings 6 a 1 and 6 b 1 , so that the light interrupting wings 6 a and 6 b does not interrupt the luminous flux b from the backlight ( see fig5 ) when they are situated at the positions shown in fig6 a . by the above - described drive mechanism 60 , the light interrupting wing 6 b can be disposed above the display member 32 as shown in the previously - described fig5 so that space can be saved . the light interrupting wing 6 may be structured so as to move on a plane surface like in a second embodiment shown in fig7 or the display member 33 may be disposed parallel to the focusing screen like in third and fourth embodiments shown in fig8 and 9 . in any of these arrangements , by disposing the light interrupting wing 6 in a position that temporarily interrupts the luminous flux b from the backlight 33 , the spaces l 5 , l 6 and l 7 in the rear of the focusing screen 4 on the optical path of the luminous flux a from the subject can be reduced compared to the conventional arrangement . in fig7 and 9 , the same members as those of fig5 are denoted by the same reference numerals . subsequently , a fifth embodiment of the present invention will be described with reference to fig1 . fig1 shows an arrangement in which the distance l 3 between the ae sensor 10 and the focusing screen 4 is shorter than that in the conventional arrangement ( see fig2 ). according to the figure , by reducing the distance l 3 between the ae sensor 10 and the focusing screen 4 , the light interrupting wing 6 is rotated more than 90 degrees . in the rotation range g , the light interrupting wing 6 interrupts a luminous flux a 2 to be captured by the ae sensor 10 , so that automatic exposure adjustment is not performed . however , since the luminous flux a 2 to be captured by the ae sensor 10 is not interrupted at positions ( 6 c and 6 d ) where the light interrupting wing 6 is stationary , automatic exposure adjustment is performed when field frame switching is finished . therefore , photographing can be performed without any problem . in such a drive mechanism for the light interrupting wing 6 , it is difficult to rotate the light interrupting wing 6 more than 90 degrees by a drive method such that the drive pins 66 and 67 are rotated by being guided by the guide grooves 63 a and 63 b like in the above - described drive mechanism 60 shown in fig6 . therefore , the light interrupting wing 6 can be driven , for example , by a drive mechanism 40 as shown in fig1 a and 11b . according to fig1 a , the focusing screen holder 62 for holding the focusing screen ( see fig6 a and 6b ) so as to be positioned has two gears 45 and 49 integrated with rotation axes 45 a and 49 a and rotatable about the rotation axes 45 a and 49 a . the rotation axes 45 a and 49 a pass through the focusing screen holder 62 to be also integrated with the light interrupting wings 6 . the focusing screen holder 62 also has an operation lever 42 that rotates about a rotation center 42 a and drive levers 43 and 47 being rotatable about rotation centers 43 a and 47 a . the drive levers 43 and 47 have toothed portions 43 b and 47 b engaging with the gears 45 and 49 . an overcharge spring 46 is fixed to the operation lever 42 . the overcharge spring 46 engages with engagement portions 43 c and 47 c of the drive levers 43 and 47 so that the movement of the operation lever 42 is transmitted to the drive levers 43 and 47 . return springs 44 and 48 engage with the drive levers 43 and 47 , so that a force that rotates the drive levers 43 and 47 in the directions of the arrows m 1 and m 2 acts on the drive levers 43 and 47 . when the operation lever 42 is rotated in the direction of the arrow j 1 , the drive levers 43 and 47 engaging with the overcharge spring 46 rotate in the directions of the arrows h 1 and h 2 . since the pitch circle diameters of the gears 45 and 49 are smaller than the pitch circle diameters of the toothed portions 43 b and 47 b , the gears 45 and 49 are rotated through accordingly larger angles in the directions of the arrows k 1 and k 2 , so that the light interrupting wings 6 can be rotated more than 90 degrees as shown in fig1 b . under this condition , the operation lever 42 can be held at the position shown in fig1 b by a holding mechanism ( not shown ) such as a click mechanism . when the operation lever 42 is rotated in the direction of the arrow j 2 from the position shown in fig1 b , the drive levers 43 and 47 are rotated in the directions of the arrows m 1 and m 2 by the return springs 44 and 48 . this moves the light interrupting wings 6 to the positions shown in fig1 a . by the above - described drive mechanism 40 , the light interrupting wings 6 can be rotated more than 90 degrees and the ae sensor can be disposed close to the focusing screen 4 as shown in the previously - described fig1 , so that space can be saved . subsequently , a sixth embodiment of the present invention will be described with reference to fig1 . in fig1 , the light interrupting wings 6 of the fifth embodiment are replaced by l - shaped light interrupting wings 6 which are formed so that the field frame can be switched between a position ( 6 c ) that covers the field limiting portion 5 a of the fixed field frame 5 and a position ( 6 e ) that is retreated from the field limiting portion 5 a . by providing the l - shaped light interrupting wings 6 like in fig6 the rotation centers of the light interrupting wings 6 can be situated in the front of an imaging plane 4 a of the focusing screen 4 on the optical path of the luminous flux a from the subject , so that the space in the rear on the optical path of the luminous flux a which space is necessary for the rotation of the light interrupting wings 6 can be reduced . when the distance between the ae sensor 10 and the focusing screen 4 is reduced , since the position ( 6 e ) that is retreated from the field limiting portion 5 a interrupts the luminous flux a 2 to be captured by the ae sensor 10 , it is necessary to rotate the light interrupting wing 6 to the position 6 d and it is necessary to shift the ae sensor 10 from a position 10 a to a position 10 b to prevent interference between the light interrupting wing 6 and the ae sensor 10 . although this arrangement requires more space in the horizontal direction of the figure , the space in the vertical direction can be reduced by δl . when the field frame is switched , the light interrupting wing 6 crosses the luminous flux a 2 to be captured by the ae sensor 10 while being rotated in the rotation range f . however , the luminous flux a 2 is not interrupted when the light interrupting wing 6 is stationary ( at the positions 6 c and 6 d ), photographing can be performed without any problem arising in automatic exposure operation . the light interrupting wings 6 as shown in the figure can be driven by a mechanism similar to the drive mechanism of the first embodiment ( see fig6 a and 6 b ). subsequently , a seventh embodiment will be described with reference to fig1 . fig1 is a top view of a camera 1 having instead of the pentagonal dach mirror a relay lens optical system with an optical path bent in the shape of the letter n by a relay lens 71 . a luminous flux c from the subject reflected at a mirror 72 passes above the light interrupting wings 6 disposed on the left and right sides of the focusing screen 4 , and space in the camera can also be reduced by reducing the distance between the light interrupting wings 6 and the luminous flux c until the light interrupting wings 6 are situated in positions that cross the luminous flux c only when the field frame is just being switched . moreover , the light interrupting wings 6 can be disposed on a secondary imaging plane s in the figure . in the figure , reference numerals 73 and 74 represent a reflecting mirror and an eyepiece , respectively . obviously , many modifications and variations of the present invention are possible in light of the above teachings . it is therefore to be understood that within the scope of the appended claims , the invention may be practiced other than as specifically described .