FIELD OF THE INVENTION 
   The present invention relates to a lens-fitted photo film unit that is preloaded with a roll of unexposed photo film and has simple photographic mechanisms, and more particularly to a lens-fitted photo film unit with an exposure value switching device. 
   BACKGROUND ART 
   Various lens-fitted photo film units preloaded with photo films are on the market. Among such lens-fitted photo film units, those which improve their imaging characteristics by enabling selecting photography modes according to brightness are known. For example “Night &amp; Day” (a trade name) is produced and sold by the present applicant. 
   The above-mentioned lens-fitted photo film unit is loaded with a high-speed photo film, and is provided with three photography modes: a day-light photography mode (with no flash light) and a day-light synch-flash photography mode (with flash light) to deal with photographing in such a bright place as outdoors in the daytime and a night-view synch-flash photography mode to deal with photographing such a dark subject as a night view or photographing with flash light a main subject like people with a dark background like a night view or a dark inside of a room while reproducing the background at an appropriate density. 
   To be more precise, a film speed of the photo film is ISO1600. The day-light and day-light synch-flash photography modes set a shutter speed at 1/120 seconds and an aperture size at f/14 in f-number. The night-view synch-flash photography mode sets the shutter speed at 1/45 seconds and the aperture size at f/6.2. According to this, as an exposure value (EV) is based on ISO100, an appropriate exposure value is EV10.8 in the day-light and day-light synch-flash photography modes and EV7.0 in the night synch-flash photography mode. 
   Using the above-mentioned high-speed photo film allows widening the range of brightness the night-view synch-flash photography mode can deal with while maintaining the usefulness. However in the event that the appropriate exposure value is switched by two stages as described above, it is impossible to fully exploit advantages of using the high-speed photo film. For example, it becomes possible to photograph quite dark scenes by lowering the shutter speed so far as it would not induce shaking and making the aperture size as large as possible for the night-view synch-flash photography mode. 
   In that case, however, such a brightness range that is beyond capacity of the camera would turn up between a brightness range covered by the night-view synch-flash photography mode and one covered by the day-light and day-light synch-flash photography modes set for photographing outdoors in the daytime. For example a preferable imaging characteristics cannot be gained in a dim inside of a room even in any photography modes. On the contrary, setting the proper exposure value for the night-view synch-flash photography mode closer to one for the day-light and day-light synch-flash photography modes makes it impossible to photograph a darker scene that is to be dealt with by the night-view synch-flash mode while maintaining the usefulness. 
   SUMMARY OF THE INVENTION 
   In view of the foregoing, a primary object of the present invention is to provide In view of the foregoing problems, an object of the present invention is to provide a lens-fitted photo film unit that can photograph scenes under a wider range of brightness taking full advantage of using a high-speed photo film. 
   To achieve the above and other objects, according to the present invention, a lens-fitted photo film unit is loaded with a photo film whose film speed is over ISO1600, and more preferably over ISO3200, and comprises a photography mode selection member for selecting one from among first to third photography modes and an exposure value switching device for switching proper exposure values in accordance with the selected photography mode, wherein the proper exposure values for the first to third photography modes satisfy the following conditions:
 
9 ≦EV 1≦12, 6.5 ≦EV 2&lt;9, 4 ≦EV 3&lt;6.5
 
wherein EV 1 , EV 2  and EV 3  represent said proper exposure values for said first to third photography modes calculated based on ISO100 respectively.
 
   This enables us to photograph under a wide range of brightness from such a dark scene as a night view to such a bright scene as outdoors during the day, exploiting the characteristics of the high-speed photo film. 
   According to a preferred embodiment, the exposure value switching device comprises an aperture size switching mechanism and a shutter speed switching mechanism, which switch over the aperture size and the shutter speed in accordance with the photography mode selected by the photography mode selection member. 
   The shutter speed switching mechanism preferably satisfies the following conditions:
 
 1/30 seconds≧ T 1≧ 1/60 seconds, 1/100 seconds≧ T 2
 
wherein T 1 and T   2  represent the low shutter speed and the high shutter speed respectively.
 
   The aperture size switching mechanism preferably satisfies the following conditions:
 
 f/ 13.0 ≦A 1,  f/ 2.8 ≦A 3≦ f/ 8.0
 
wherein A 1  and A 3  represent the small aperture size for said first photography mode and the large aperture size for said third photography mode in terms of f-number.
 
   In a lens-fitted photo film unit that comprises a flash device, the flash device is turned ON or OFF in cooperation with the photography mode selection member, and the flash device has a guide number of 4 (ISO100·m) or less. A main capacitor of the flash device preferably has a capacitance of 40 μF or less. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and advantages will be more apparent from the following detailed description of the preferred embodiments when read in connection with the accompanied drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, and wherein: 
       FIG. 1  is an external perspective view of a lens-fitted photo film unit in a standard photography mode according to an embodiment of the present invention; 
       FIG. 2  is an external perspective view of the lens-fitted photo film unit in an indoor photography mode; 
       FIG. 3  is an external perspective view of the lens-fitted photo film unit in a night-view photography mode; 
       FIG. 4  is an exploded perspective view illustrating the lens-fitted photo film unit; 
       FIG. 5  is an exploded perspective view illustrating an aperture size switching mechanism and a shutter speed switching mechanism; 
       FIG. 6  is an explanatory view illustrating a high shutter speed position of a stop lever; 
       FIG. 7  is an explanatory view illustrating a low shutter speed position of the stop lever; 
       FIG. 8  is an explanatory view illustrating a shutter release operation in the high shutter speed position; 
       FIG. 9  is an explanatory view illustrating a shutter release operation in the low shutter speed position; 
       FIG. 10  is an explanatory view illustrating the aperture size and the shutter speed switching mechanisms in the standard photography mode; 
       FIG. 11  is an explanatory view illustrating the aperture size and the shutter speed switching mechanisms in the indoor photography mode; 
       FIG. 12  is an explanatory view illustrating the aperture size and the shutter speed switching mechanisms in the night-view photography mode; 
       FIG. 13  is an explanatory view illustrating an aperture size switching mechanism and a shutter speed switching mechanism in a standard photography mode, according to a second embodiment with two kinds of aperture sizes; 
       FIG. 14  is an explanatory view illustrating the aperture size and the shutter speed switching mechanisms in an indoor photography mode of the second embodiment; and 
       FIG. 15  is an explanatory view illustrating the aperture size and the shutter speed switching mechanisms in a night-view photography mode of the second embodiment. 
   


   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows an external view of a lens-fitted photo film unit according to an embodiment of the present invention. The lens-fitted photo film unit  2  consists of a unit body  3  incorporating various photographic mechanisms, a film cartridge loaded in the unit body  3  in the factory and an attached label  4  wrapping around outer circumference of the unit body  3 . The label  4  has apertures to expose some parts of the unit body  3 . 
   The unit body  3  is provided with a taking lens  5 , a viewfinder  6 , a flash projector  7  and a photography mode selector  8  at the front. The unit body  3  has a shutter button  9 , an exposure counter window  10  and a signaling aperture  11  on the top. A part of a film winding wheel  12  exposes from the back of the unit body  3 . 
   The photography mode selector  8  consists of an operation aperture  14  formed at the front of the unit body  3  and an almost oval operation member  15  which is movable within the operation aperture  14 . The operation member  15  as a photography mode selecting member moves among a first operational position located lower in the operation aperture  14  shown in  FIG. 1 , a second operational position slid upward from the first operational position shown in  FIG. 2  and a third operational position turned clockwise from the second operational position shown in  FIG. 3 . 
   When the operation member  15  is in the first operational position, the lens-fitted photo film unit  2  is in a standard photography mode (a first photography mode) with no flash light, a small aperture and a high shutter speed. When the operation member  15  is in the second operational position as shown in  FIG. 2 , the lens-fitted photo film unit  2  is in an indoor photography mode (a second photography mode) with flash light, a middle aperture and the high shutter speed. In the indoor photography mode, a signaling member  17  is protruded from the top of the lens-fitted photo film unit  2 . The signaling member  17  is a light guide that guides light from a light emitting element, which emits on completion of charging a flash lamp, to outside the unit body  3 , informing of being ready for photographing. 
   When the operation member  15  is in the third operational position as shown in  FIG. 3 , the lens-fitted photo film unit  2  is in a night-view photography mode (a third photography mode) with the flash, a large aperture and a low shutter speed. In the night-view photography mode, a tabular darkening member  19  is inserted from below to the front of the flash projector  7  so as to reduce the quantity of flash light. A circular index disc  20  is also protruded to the front of the viewfinder  6 . To make a visual identification of the index disc  20  in the viewfinder  6  enables a photographer to know that the lens-fitted photo film unit  2  is in the night-view photography mode. 
     FIG. 4  is an exploded perspective view illustrating the unit body  3 . The unit body  3  consists of a body base  23  where a 135-type film cartridge  22  is loaded, a flash device  24  attached at the front of the body base  23 , an interconnection mechanism  25  to switch the photography modes in conjunction with the operation member  15 , a front cover  26  and a rear cover  27  set at the front and back of the body base  23 . 
   The film cartridge  22  consists of a photo film  22   a  and a cartridge shell  22   b . As for the photo film  22   a , a high-speed film of over ISO1600 is preferable, one of over ISO3200 is more preferable. According to this embodiment, a film speed of the photo film  22   a  is ISO3200. 
   The flash device  24  has a printed circuit board  29  which is attached with various electric parts including a main capacitor  28  and forms a flash circuit and the flash projector  7  consisting of a flash discharge tube, a reflector and a diffuser. The printed circuit board  29  is provided with a sync-flash switch  30  which turns on in synchronism with opening and closing of a shutter blade, a metal contact strip  31  constituting a flash charge switch which turns on or off with the move of the operation member  15  in the photography mode selector  8 , and a battery contact strip  33  which connects a battery  32 , a power source of the flash device  24 , with the flash circuit. 
   Turning on the flash charge switch allows the flash circuit to charge the main capacitor  28  with high voltage. Turning on the sync-flash switch  30  makes the charge stored in the main capacitor  28  discharge through the flash discharge tube, letting the flash discharge tube project the flash light. When the flash charge switch is off, the flash light is not projected because the main capacitor  28  doesn&#39;t discharge even if the sync-flash switch  30  is turned on. 
   As for the flash device  24 , the quantity of flash light is set smaller and a guide number is less then 4 (ISO100·m) responding to using the high-speed film as the photo film  22   a . According to this embodiment, the guide number is normally 2.8 (ISO100·m) and is reduced to 2.0 (ISO100·m) when the darkening member  19  is inserted to the front of the flash projector  7 . 
   The quantity of flash light is set smaller by use of a smaller capacitance of the main capacitor  28  than conventional, which at the same time offers an advantage in miniaturization. Because the smaller quantity of flash light reduces electric power consumption, a smaller battery than conventional can be used as the battery  32  while maintaining the same battery life as ever before, which is also beneficial to miniaturization. The capacitance of the main capacitor  28  is preferably not more than 40 μF. As the battery  32 , the same or smaller size than the AAA-size is preferable and for example an N-size battery is desirable. 
   At the center front of the body base  23 , an image tunnel  35  is provided. Around the image tunnel  35 , a shutter charging mechanism, a shutter mechanism, a film winding mechanism, a film winding-lock mechanism, a frame counter mechanism, an imaging optical system, a viewfinder optical system, an exposure value switching device being constituted of an aperture size switching mechanism and a shutter speed switching mechanism are built in. 
     FIG. 5  is an exploded perspective view illustrating the shutter mechanism, the aperture size switching mechanism, the shutter speed switching mechanism and the imaging optical system built in around the image tunnel  35 . At the front of the image tunnel  35 , a rectangle picture aperture  36  is formed. At the side, a pin  38  which pivotally holds a shutter blade  37  and another pin  40  on which an end of a spring  39  is hooked are provided. 
   The shutter blade  37  constituting the shutter mechanism consists of a base section  42  which forms a hole  42   a  for insertion of the pin  38 , a blade section  43  which is arranged in front of the picture aperture  36  and opens and closes the picture aperture  36 , and a connecting section  44  between the base section  42  and the blade section  43 . The base section  42  is provided with a pin  42   b  on which the other end of the spring  39  is hooked, a projection  42   c  kicked by a shutter drive lever  45  and a synchronizing projection  42   d . The shutter blade  37  is hold in a closing position to cover in the picture aperture  36  with bias of the spring  39 . 
   The shutter drive lever  45 , a part of the shutter mechanism, turns in an opposite direction to an arrow D 1  in the drawing by the shutter charging mechanism and is set in a charging position. And responding to the shutter release button  9  being pressed, the shutter drive lever  45  turns in a direction of the arrow D 1  toward a charge releasing position and kicks the projection  42   c  of the shutter blade  37  during the turn. As being kicked by the shutter drive lever  45 , the shutter blade  37  swings in an opposite direction to an arrow D 2  in the drawing against the bias of the spring  39 , fully opens the picture aperture  36  and then returns to the closing position with the bias of the spring  39 . Via the full-open position where the picture aperture  36  fully opens, the shutter blade  37  can swing to a terminal position where it contacts with a stopper pin  53   a  (see  FIGS. 8 and 9 ) provided inside a lens holder  53 . 
   While swinging to the terminal position, the shutter blade  37  presses an upper metal contact strip  30   a  of the sync-flash switch  30  by the synchronizing projection  42   d , to bring it into contact with a lower metal contact strip  30   b . The contact of the pair of metal contact strips  30   a  and  30   b  turns on the sync-flash switch  30 . 
   On the top of the lens holder  53 , a pin  47  which pivotally holds a stop lever  46  is formed. The stop lever  46  consists of a boss  48  held by the pin  47  and arms  49  and  50  protruded from the side of the boss  48 . A top of the arm  49  is provided with a pad  49   a.    
   The stop lever  46  turns between a high shutter speed position where the pad  49   a  is inserted below and touches a free end of the lower metal contact strip  30   b  as shown in  FIG. 6 , and a low shutter speed position where the pad  49   a  is retreated from below of the lower metal contact strip  30   b  as shown in  FIG. 7 . 
   While the stop lever  46  is in the high shutter speed position as shown in  FIG. 8 , the shutter release lets the flash light be projected because the upper metal contact strip  30   a  is pressed by the synchronizing projection  42   d  of the shutter blade  37 , to contact with the lower metal contact strip  30   b  of the sync-flash switch  30 . Because the lower metal contact strip  30   b  is in contact with the pad  49   a , the swing of the shutter blade  37  is stopped at the full-open position on the way to the terminal position. For this reason, the shutter blade  37  returns to the closing position in a short time, which makes it possible to gain a high shutter speed of 1/100 seconds. 
   When the stop lever  46  is in the low shutter speed position as shown in  FIG. 9 , the shutter blade  37  can swing to the terminal position, so it swings through a larger range. It is because the elastic deformation of the lower metal contact strip  30   b  becomes free. As a result, it takes longer for the shutter blade  37  to return to the closing position, providing a lower shutter speed of 1/45 sec. 
   As shown in  FIG. 5 , the lens holder  53  is mounted in front of the image tunnel  35 . At the center front of the lens holder  53 , a tubular lens barrel  54  is formed. An aperture  55  is formed inside the lens barrel  54 , and a notch  56  on the side of the lens barrel  54 . A first lens  5   a  and a second lens  5   b  constituting the taking lens  5  are housed in the lens barrel  54 . Between the first and second lenses  5   a  and  5   b  are held a large aperture blade  60 , a first aperture size switching blade  61 , a second aperture size switching blade  62  and a spacer  64  to ensure a space for the insertion of the aperture size switching blades  61  and  62 , constituting the aperture size switching mechanism. The large aperture blade  60  is a circular, thin blade and has a large stop aperture  60   a  of a large diameter in the center. An aperture of the spacer  64  is larger than the large stop aperture  60   a  in diameter. 
   To the front of the lens holder  53  is attached a lens holder plate  66  in order not to have the taking lens  5  and other parts housed in the lens barrel  54  and a switching ring  65  mounted around outer circumference of the lens barrel  54  drop off. 
   The first aperture size switching blade  61  has a middle aperture section  61   a  at one end to cover the large stop aperture  60   a , and the middle aperture section  61   a  has a middle stop aperture  61   b  of a smaller diameter than the large stop aperture  60   a . The first aperture size switching blade  61  also has a hole  61   c  and a crooked slot  61   d  at the other end. The hole  61   c  is pivotally fit on a pin  67  formed near the lens barrel  54  of the lens holder  53 . The first aperture size switching blade  61  turns between an inserting position where the middle stop aperture  61   b  is located on an optical axis of the taking lens and a retreating position where the middle aperture section  61   a  retreats from the notch  56  to outside of the lens barrel  54  to expose the large stop aperture  60   a.    
   The second aperture size switching blade  62  has a small aperture section  62   a  of the almost same size as the middle aperture section  61   a  at one end. In the middle of the small aperture section  62   a  is formed a small stop aperture  62   b  of a smaller diameter than the middle stop aperture  61   b . The second aperture size switching blade  62  also has an engaging pin  62   c  at the other end. The second aperture size switching blade  62  is pivotally held as a hole  62   d  of the second aperture size switching blade  62  is fit on a pin  68  formed on the lens holder  53 . 
   Along with the first aperture size switching blade  61 , the second aperture size switching blade  62  turns between an inserting position where the small stop aperture  62   b  is located on the optical axis of the taking lens and a retreating position where the small aperture section  62   a  retreats from the notch  56  to outside of the lens barrel  54  and comes into contact with a pin  69  formed on the lens holder  53 . A spring  70  makes the second aperture size switching blade  62  biased to the retreating position with one end being hooked on the second aperture size switching blade  62  and the other end on a pin  71  formed on the lens holder  53 . 
   The switching ring  65  is fit on and turns around outer circumference of the lens barrel  54 . The switching ring  65  is provided with a pin  65   a  where an end of a spring  73  is hooked, a link pin  65   b  which is inserted into the slot  61   d  of the first aperture size switching blade  61 , a pair of nipping pins  65   c  which nip the other arm  50  of the stop lever  46 , and a driven pin  65   d  protruded to the back side. 
   The spring  73  biases the switching ring  65  to turn in a direction of an arrow D 3  in the drawing, with one end being hooked on a pin  74  formed at a lower front position of the lens holder  53 . The switching ring  65  biased by the spring  73  is held in a given position by the first aperture size switching blade  61 . 
   The operation member  15  is integrated with an almost oval switching blade  76  which is integrated with a press lever  77  protruded in a horizontal direction. The engaging pin  62   c  of the second aperture size switching blade  62  is located on a moving track of the press lever  77  when the operation member  15  slides between the first and second operational positions. And the driven pin  65   d  of the switching ring  65  is located on the turning track of the press lever  77  when the operation member  15  turns between the second and third operational positions. 
     FIG. 10  illustrates a state in the standard photography mode. When the operation member  15  is in the first operational position, the press lever  77  is not in contact with the driven pin  65   d  of the switching ring  65 . For this reason, the switching ring  65  is held in an initial position by the first aperture size switching blade  61 . 
   When the switching ring  65  is in the initial position, the pair of nipping pins  65   c  holds the stop lever  46  in the high shutter speed position. And the first aperture size switching blade  61  is in the inserting position by the link pin  65   b  where the middle aperture section  61   a  is inserted into the lens barrel  57 . Moreover the second aperture size switching blade  62  biased by the spring  71  is in the inserting position where the small aperture section  62   b  is inserted into the lens barrel  57  by the engaging pin  62   c  as it is engaged with the lower portion of the press lever  77 . This provides a small aperture state where the quantity of light is limited at the small stop aperture  62   c.    
     FIG. 11  illustrates a state in the indoor photography mode. When the operation member  15  is in the second operational position, the switching ring  65  is held in the initial position by the first aperture size switching blade  61  because the press lever  77  does not contact the driven pin  65   d  like as in the first operational position. For this reason, the stop lever  46  is in the high shutter speed position and the first aperture size switching blade  61  is in the inserting position. On the other hand, the second aperture size switching blade  62  turns with the movement of the press lever  77  to the retreating position where it is in contact with the pin  69 , biased by the spring  71 . This allows the small aperture section  62   b  to retreat from the lens barrel  54  and makes an aperture state where the quantity of light is limited at the middle stop aperture  61   c.    
   As shown in  FIG. 12 , in the night-view photography mode, the press lever  77  presses the driven pin  65   d  from below and turns the switching ring- 65  counterclockwise in the drawing when the operation member  15  turns from the second operational position to the third operational position. With the turn of the switching ring  65 , the first aperture size switching blade  61  pressed by the link pin  65   b  turns clockwise in the drawing, which makes a large aperture state where the middle aperture section  61   a  retreats from the optical axis and the quantity of light is limited at the large stop aperture  60   a  of the aperture blade  60 . And the pair of nipping pin  65   c  turns the stop lever  46  and sets it in the low shutter speed position. 
   The signaling member  17 , the darkening member  19 , the index disc  20  and the metal contact strip  31  constituting a charging switch are interconnected with the operation member  15  by the interconnection mechanism. As the operation member  15  slides between the first and second operational positions, the signaling member  17  moves up and down and the charging switch turns on or off. And as the operation member  15  turns between the second and third operational positions, the index disc  20  and the darkening member  19  are inserted into or retreated from the front of the viewfinder  6  and the flash projector  7 , respectively. 
   The above-mentioned lens-fitted photo film unit  2  uses the photo film  22   b  whose film speed is ISO3200. In the standard photography mode, the shutter speed is 1/100 sec., an aperture size is f/16 in f-number, and no flash light is projected. And in the indoor photography mode, the shutter speed is 1/100 sec., the aperture size is f/5.6 and a flash light of GN2.8 (ISO100·m) is projected. Moreover in the night-view photography mode, the shutter speed is 1/45 sec., the aperture size is f/4.0 and a flash light of GN2.0 (ISO100·m) is projected. 
   In the standard photography mode, an appropriate exposure value is EV9.6 as the EV is based on ISO100. In the same way, the appropriate EV is EV6.6 in the indoor photography mode and EV4.5 in the night-view photography mode. With consideration for latitude of the photo film  22   b , this enables us to photograph under a wide range of brightness from such a dark scene as a night view to an ordinary photographic scene in the outdoors during the day. It is to be noted that the appropriate exposure value EV on the basis of ISO100 is represented by the following formula: EV=log2 (F2/T)−log2 (S/100) wherein F represents an aperture size, T represents the shutter speed (sec.) and S represents a film speed. 
   The aperture sizes and the shutter speeds for the respective photography modes are not limited to the above-mentioned combinations insofar as the respective proper exposure values satisfy the following conditions: 9≦EV1≦12, 6.5≦EV2≦9, 4=EV3=6.5, wherein the proper exposure values for the standard photography mode (the first photography mode), the indoor photography mode (the second photography mode) and the night-view photography mode (the third photography mode) are designated as EV1, EV2 and EV3, respectively. With consideration for shaking and a depth of field, however, it is preferable to use the film speed of over ISO1600, and more preferable over ISO3200 as mentioned above, and set the high shutter speed equal to or higher than 1/100 sec., set the low shutter speed at a value between 1/30 and 1/60 sec., make the small aperture size over f/13 and the large aperture size between f/2.8 and f/8 in f-number. 
   With ISO3200, the aperture size is f/5.6 and the guide number is 2.8 (ISO100·m) in the indoor photography mode, whereas in the night-view photography mode the aperture size is f/4.0 and the guide number is 2.0 (ISO100·m). In both photography modes, it is possible to photograph a subject at a photographic distance of about 2.8 m at an appropriate exposure amount with the flash light. And with consideration for the latitude of the photo film and allowance of under-exposure of about 1.5 EV, it is also possible to photograph with the flash light a subject within a subject distance of about 5 m in a satisfactory quality level. 
   Next, the operation of the above-described embodiment will be explained. When photographing in such a bright place as outdoors on a sunny day, the standard photography mode is selected by sliding the operation member  15  down to the first operational position in the operation aperture  14  as shown in  FIG. 1 . 
   When the operation member  15  is in the first operational position, the switching ring  65  is in the initial position biased by the spring  73  and the first aperture size switching blade  61  is set in the inserting position as shown in  FIG. 10 . The second aperture size switching blade  62  is set in the inserting position because the engaging pin  62   c  engages with the press lever  77 . In addition, the stop lever  46  is set in the high shutter speed position as shown in  FIG. 6 . 
   Moreover in the standard photography mode, the metal contact strip  31  of the charging switch of the flash device  24  isn&#39;t pressed, the signaling member  17  doesn&#39;t protrude from an upper face of the unit body  3 , and the darkening member  19  and the index disc  20  aren&#39;t exposed at the front of the lens-fitted photo film unit  2 . 
   When the shutter button  9  is pressed to photograph in the standard photography mode, the shutter blade  37  starts to turn from the closing position, but the turn is stopped on the way by the stop lever  46  via the sync-flash switch  30 . Consequently, the shutter blade  37  returns to the closing position after turning to the full-open position as shown in  FIG. 8 , so the shutter speed becomes higher. And since the second aperture size switching blade  62  is in the inserting position, the light entering through the taking lens  5  is limited at the stop aperture  62   a . Moreover as the charging switch is off, any flash light isn&#39;t projected even if the sync-flash switch  30  is turned on. Thus photographs are taken with 1/100 seconds of the shutter speed and f/16 of the aperture size and without flash light. 
   To photograph a dim place as indoors or people indoors while reproducing a background at appropriate density, the indoor photography mode is selected by sliding the operation member  15  up to the second operational position in the operation aperture  14  as shown in  FIG. 2 . 
   When the operation member  15  is in the second operational position, the charging switch turns on and the signaling member  17  protrudes from the upper face of the unit body  3 , but the switching ring  65  is in the initial position and the first aperture size switching blade  61  is set in the inserting position. On the other hand, the second aperture size switching blade  62  turns to the retreating position biased by the spring  71  because the press lever  77  engaged with the engaging pin  62   c  moves upward. Consequently, the light entering through the taking lens  5  is limited by the middle stop aperture  61   b  of the first aperture size switching blade  61 . Thus in the indoor photography mode, photographs are taken with 1/100 seconds of the shutter speed, f/5.6 of the aperture size and flash light with the quantity of 2.8 in guide number. 
   When photographing such a dark subject as the night view or photographing a main subject like a person with a background of the night view while reproducing the background at appropriate density, the night-view photography mode is selected turning the operation member  15  from the second operational position to the third operational position as shown in  FIG. 3 . 
   When the operation member  15  turns to the third operational position, the press lever  77  presses the driven pin  65   a  from below. For this reason, the switching ring  65  turns from the initial position against the bias of the spring  73 . With the turn of the switching ring  65 , the first aperture size switching blade  61  turns to the retreating position. The stop lever  46  is set in the low shutter position as shown in  FIG. 7 . 
   In conjunction with the turn of the operation member  15  from the second operational position to the third operational position, the darkening member  19  is placed in front of the flash projector  7  and the index disc  20  is placed in front of the viewfinder  6 . In addition, the charging switch is kept on and the signaling member  17  is also kept protruded from the upper face of the unit body  3 . 
   When photographing in the night-view photography mode, the shutter opens and closes at the low shutter speed of 1/45 seconds and the flash light is projected in sync with this. The quantity of light is limited at the large stop aperture  60   a  that is at the aperture size of f/4.0 because the light from the subject entering through the taking lens  5  exposes the photo film through the large stop aperture  60   a  during the shutter blade  22  opens and closes. The flash light is projected reduced by the darkening member  19  and as a result the quantity of flash light of the guide number 2.0 illuminates the subject. 
   It is possible to photograph well under the wide range of brightness for example in the bright place as outdoors on the sunny day, in the dim place as indoors, or in the dark place as outdoors at night by selecting respective photography modes as described above. In other words, it is possible to photograph well from a dark scene exploiting the high speed of the photo film  22   a  to such a bright scene as outdoors on the sunny day. 
   Now, another embodiment of the present invention will be explained. As described below, this embodiment is the same as the above described embodiment except that it uses two kinds of aperture sizes and a higher shutter speed than that used in the first embodiment, so the explanation will be omitted by applying the same numbers to the same components. 
   States of an exposure value switching device in a standard photography mode, an indoor photography mode and a night-view photography mode are shown in  FIG. 13 ,  FIG. 14  and  FIG. 15 , respectively. On an optical axis of a taking lens, a large aperture blade  81  forming a large stop aperture  81   a  is arranged and the large stop aperture  81   a  is an aperture size of f/6.2. An aperture size switching blade  82  is provided with a small aperture section  82   a  whose size is enough to cover the large stop aperture  81   a  and which has a small stop aperture  82   b  in the middle. The small stop aperture  82   b  is an aperture size of f/14.0. 
   The aperture size switching blade  82  turns with the move of a operation member  15  as shown in  FIGS. 13 and 14  between an inserting position where the small stop aperture  82   b  is placed on the optical axis of the taking lens and a retreating position where the small aperture section  82   a  retreats outside a lens barrel  54  to expose the large stop aperture  81   a . The aperture size switching blade  82  is in the inserting position and in the retreating position when the operation member  15  is in a first operational position and in a second operational position, respectively. A mechanism which turns the aperture size switching blade  82  is the same as one which turns the second aperture size switching blade  62  according to the above described embodiment. 
   The strength of a spring  39  which biases a shutter blade  37  and position of a stopper  53   a  to control a rotary angle of the shutter blade  37  are adjusted so as to provide a shutter speed of 1/120 seconds (a high shutter speed) when a stop lever  46  is in a high shutter speed position, and a shutter speed of 1/45 seconds (a low shutter speed) when in a low shutter speed position. 
   In the same way as the above described embodiment, there is no flash light in a standard photography mode and the flash light is projected in a indoor and a night-view photography modes. In response that the same large aperture (an aperture size of f/6.2) is used both in the indoor and the night-view photography modes, the quantity of flash light is the same. According to this embodiment, a guide number is 3.0 and a darkening member  19  isn&#39;t placed in front of a flash projector  7  even in the night-view photography mode. In this case, it is also possible to photograph with the flash light a subject about 2.8 m away under an appropriate exposure amount and even a subject about 5 m away in a satisfactory level. 
   An above-mentioned lens-fitted  2  uses a photo film whose film speed is ISO3200. In the standard photography mode, the shutter speed is 1/120 sec., an aperture size is f/14.0 and no flash light is used. And in the indoor photography mode, the shutter speed is 1/120 sec., the aperture size is f/6.2 and the flash light of GN3.0 (ISO100·m) is projected. Moreover in the night-view photography mode, the shutter speed is 1/45 sec., the aperture size is f/6.2 and the flash light of GN3.0 (ISO100·m) is projected. 
   In the standard photography mode, an appropriate exposure value is EV9.5 as the EV is based on ISO100. In the same way, the appropriate exposure value is EV7.2 in the indoor photography mode, and EV5.8 in the night-view photography mode. With consideration for latitude of a photo film  22   b , this enables us to photograph under a wide range of brightness from at such a dark scene as a night view to at such a normal scene as outdoors during the day. 
   In the above described embodiment, photographing with the flash light is in the indoor and the night-view photography modes. It is possible, however, to photograph with no flash light in the standard and indoor photography modes and to photograph with the flash light in the night-view photography mode. It is also possible to photograph with no flash light in the standard and night-view photography modes and to photograph with the flash light in the indoor photography mode.
A lens-fitted photo film unit is preloaded with a roll of photo film whose film speed is ISO3200, and has a mode selection member that is manually operated to select one of a standard photography mode, an indoor photography mode and a night-view photography mode. In the standard photography mode, an exposure is made without flash with a small aperture size and at a high shutter speed. In the indoor photography mode, an exposure is made with a flashlight, with a middle aperture size and at a high shutter speed. In the night-view photography mode, an exposure is made with a flash light, with a large aperture size and at a low shutter speed.