it is an object to provide an inexpensive digital camera having a simple constitution in which before photographing , perspective is being observed and is simultaneously adjusted suitably , and distortion of an image such as high building is prevented so that a satisfactory picture . this object is realized by providing a perspective control mechanism that moves an image pickup element to a direction vertical to an optical axis of a photographing lens and longitudinal and lateral directions which are perpendicular to each other so as to adjust the image pickup element . in the best embodiment of the present invention , the digital camera includes a longitudinal direction position adjusting mechanism and a lateral direction position adjusting mechanism that press to attach an image pickup substrate mounted with the image pickup element to be attached to a front surface or a rear surface of a frame ( body frame ) in a camera main body using a plate spring or the like and independently move the image pickup substrate to a longitudinal direction and a lateral direction of the image pickup substrate . as a result , the position of the image pickup element can be adjusted so that an image projected by the photographing lens is imaged in a predetermined position on the image pickup element . the image pickup substrate mounted with the image pickup element is mounted to the frame of the camera main body in a sliding state , and a rack is mounted to both ends of the image pickup substrate . the racks can be driven and adjusted directly by one pinion , and in this case , a posture of the image pickup substrate is restrained and a position of the image pickup substrate in a lengthwise direction of the pinion is fee . similarly , a rack and a pinion are provided to one end in a direction perpendicular to the above racks and the pinion , and the position of the image pickup substrate in the direction perpendicular to above - mentioned direction can be adjusted to a free position by these provided rack and pinion . the position of image pickup element mounted to the image pickup substrate is , therefore , adjusted to the perpendicular two directions independently , so that the perspective of the image can be controlled . a perspective control device may be mechanistically constituted so as to be capable of moving and adjusting the image pickup element in the above manner , but its adjusting state should be easily and visually checked . in the case where , for example , an object is a building , at a determination whether the perspective is adjusted , all vertical lines of an image should be parallel . further , all horizontal lines should be parallel depending on photographing scene . needless to say , since a picture is one kind of expression , the present invention is not always limited to this . in a conventional single - lens reflex camera , a lattice is printed ( carved ) on a focusing glass , but since the lattice on the focusing glass is fixed , the lattice does not mostly match with the vertical lines or the horizontal lines of an object image such as building . this makes accurate adjustment difficult . an image captured by the image pickup element is , therefore , displayed as a finder image on an electronic display , but at this time , one or a plurality of indicator line ( s ) is ( are ) displayed as software display in the longitudinal and lateral directions . the indicator lines are moved to be displayed over an entire display surface of the electronic display by an operating member such as an operation key . as a result , the indicator lines are matched with an arbitrary position of the finder image , and the perspective is visually checked to be adjusted to an optimal state . as one example of a dust intrusion preventing measure , a transparent glass or a resin plate is mounted to the front surface of the camera , so that a sealed structure is obtained . in this case , in order to improve a dew condensation preventing effect , a dry air ( nitrogen , argon gas or the like if possible ) is injected into a sealed portion , so that an airtight structure is obtained . even in the case of the airtight structure , a pressure difference occurs between an inside of the camera and atmospheric air due to temperature change or altitude difference , and thus a strong force is applied a dustproof plate such as a glass plate . further , even if a o ring is mounted to a portion where the pinion shaft or the like of the perspective control mechanism pierces an outer wall of the camera main body , there is a fear that a movable portion such as the o ring cannot tolerate long - term pressure . in order to solve this problem , the pressure difference inside and outside the camera main body is eliminated . in order to eliminate the pressure difference , a diaphragm , a closed - end cylindrical bellows , or a flexible partition ( flexible partitioning member ) such as a resin film is provided between a mechanism portion that should maintain airtightness of the camera main body and atmospheric air . the digital camera having the perspective control mechanism according to a concrete embodiment of the present invention is explained below . this embodiment is the digital camera in which before photographing , an image to be imaged on the image pickup element is being visually checked on the electronic display , and simultaneously the perspective is controlled so that the image is photographed . the image pickup substrate mounted with the image pickup element is pressed to the front surface or the rear surface of the body frame of the camera by the plate spring and is mounted thereto so that an image is imaged on the image pickup element . first racks are fixed to vicinities of both ends of the image pickup substrate in the longitudinal direction , respectively . meanwhile , a bearing that supports a first pinion is annexed to body frame portions on both outsides to which the image pickup substrate is mounted , and the first pinion is engaged with the first racks so that the posture of the image pickup substrate is guided . at the same time , the first pinion is constituted so as to be capable of locating the image pickup substrate to a direction tangential with respect to its pitch circle and a direction vertical to the optical axis of the photographing lens . similarly , a second pinion perpendicular to the first pinion and second rack are provided , and the second pinion is engaged with the second rack only at one end . the image pickup substrate is constituted so as to be capable of being located to a direction perpendicular to the direction adjusted by the first pinion . a first operation knob ( first operation member ) annexed to the first pinion and a second operation knob ( second operation member ) annexed to the second pinion are independently turned , so that the image pickup element mounted to the image pickup substrate is adjusted to arbitrary positions in the perpendicular directions vertical to the optical axis of the photographing lens . a photographer visually checks and adjusts the perspective on the electronic display and then photographs an object . as the indicator lines on the electronic display , one or a plurality of lines is ( are ) displayed as software display in the vertical direction and the lateral direction , and the vertical and lateral lines are constituted so as to be capable of being independently moved to be adjusted in the arbitrary positions . further , in a lens interchangeable digital camera , the dustproof glass or the resin plate is fixed as the dustproof plate to a position just after the interchangeable lens in the camera main body , so that the inside of the camera main body has the sealed structure . as a result , dust is prevented from adhering to the surface of the image pickup element provided into the camera main body . the diaphragm which deflects freely and the close - end cylindrical bellows or a screen made of resin or the like is provided between the mechanism portion and a casing of the camera , so that the camera mechanism portion is shielded against air and is sealed . at the same time , a mechanism that reduces the pressure difference between the inside of the camera and atmospheric air due to temperature change , altitude change and the other weather conditions is provided . a concrete constitutional example of the digital camera 14 according to the present invention is shown in fig1 . fig1 is a sectional view illustrating a state viewed from a rear side ( photographer side ) of the digital camera 14 , but the same constitution as the state shown in fig1 can be used in the front side ( photographing lens side ) of the digital camera 14 . in this case , however , the image pickup element 3 shown by a broken line in fig1 is naturally mounted so that an exposing surface of the image pickup element 3 faces a front side on the sheet surface of fig1 ( shown by a solid line ) an opening 4 is provided to a center of an inner rear surface of the body frame 1 in the camera , and the square image pickup substrate 2 mounted with the image pickup element 3 is attached to a flat surface around the opening 4 . in this case , the image pickup substrate 2 is held to the flat surface by the plate springs ( pressing members ) 5 whose base ends are fixed to the camera main body in the pressed and fixed state . as a result , the image pickup substrate 2 is accurately located to the optically axial direction of the photographing lens , not shown , and even if an external force such as deadweight or slight impact is applied thereto , the position of the image pickup element 3 is fixed in an unmovable state . the first racks 8 are fixed to the vicinities of the right and left ends above the image pickup substrate 2 in the up - down direction ( the longitudinal direction of the image pickup substrate 2 ). both the ends of the first pinion 7 extended to the right - left direction ( the lateral direction of the image pickup substrate 2 ) are engaged with the right and left racks 8 , and the right and left ends of the pinion 7 are supported by the bearings 9 on the side of the camera main body rotatively . movement of the image pickup substrate 2 to the rotating direction is , therefore , restrained with respect to the optical axis of the photographing lens , and its position in the up - down direction in the drawing is restricted by the pinion 7 . further , the operation knob 6 for rotation is annexed to the left end of the pinion 7 . when the pinion 7 is rotated by the operation knob 6 , the position of the image pickup substrate 2 in the up - down direction can be suitably driven to be adjusted via the racks 8 . the second rack 12 is fixed to the vicinity of the upper end of the image pickup substrate 2 in the right - left direction ( the lateral direction of the image pickup substrate 2 ). the second pinion 11 extended to the up - down direction is engaged with the rack 12 , and the pinion 11 is supported by the bearing 13 on the side of the camera main body rotatively . further , an operation knob 10 for rotation is annexed to the upper end of the pinion 11 . when the pinion 11 is rotated by the operation knob 10 , the position of the image pickup substrate 2 can be suitably driven to be adjusted via the rack 12 . at the time of photographing , therefore , when the operation knob 6 annexed to the pinion 7 and the operation knob 10 annexed to the pinion 11 are independently turned , the image pickup element 3 mounted to the image pickup substrate 2 is suitably adjusted to arbitrary positions in the right - left direction and the up - down direction with respect to the optical axis of the photographing lens . the pinion 7 and the pinion 11 can be replaced by cams , and the racks 8 and the rack 12 can be replaced by cam followers . even in such a constitution , the position adjustment which is equivalent to the above one can be made . the lateral direction position adjusting mechanism and the longitudinal direction position adjusting mechanism of the present invention , namely , the driving mechanisms that independently move the image pickup substrate 2 to the right - left direction and the up - down direction are not limited to the rack and pinion type or cam type ones , and another types of driving mechanisms can be suitably adopted according to design . according to the embodiment in fig1 , before an object such as a tower block is photographed , the image pickup substrate 2 is independently moved to the longitudinal direction and the lateral direction so as to be located so that the image photographed by the photographing lens is imaged on the image pickup element 3 . for this reason , the image pickup element 3 is easily adjusted to desired positions in the longitudinal and lateral directions . the photographer , therefore , visually checks and adjusts the perspective state of the image on the electronic display , and can photograph the object , so as to be capable of getting a satisfactory picture without distortion of the photographed image . fig2 illustrates one example of the electronic display ( finder ) 21 of the digital camera 14 according to the present invention . vertical lines 22 and 23 as the vertical direction indicator lines are displayed as software display on the electronic display 21 , and lateral lines 24 and 25 as the lateral direction indicator lines are displayed as software display on the electronic display 21 . as to the indicator lines 22 to 25 , only the vertical lines 22 and 23 or the lateral lines 24 and 25 may be selectively displayed by using an operation switch , for example , at the time of photographing , or only one of the vertical lines 22 and 23 or one of the lateral lines 24 and 25 may be suitably displayed . in the example of the drawing , the positions of the vertical lines 22 and 23 and the lateral lines 24 and 25 can be independently moved to be adjusted by seesaw switches ( operating section for displaying vertical lines ) 202 and 203 and seesaw switches ( operating section for displaying lateral lines ) 204 and 205 . in this case , arrows or the like are marked on the surfaces of the seesaw switches 202 to 205 so as to display the moving directions of the indicator lines 22 to 25 corresponding to the switches . a form and a constitution of the operating members for adjusting the positions of the indicator lines 22 to 25 , namely , switches and buttons are not particularly limited , and thus publicly - known operating units such as switches and buttons can be widely adopted as long as they can independently move the indicator lines 22 to 25 to arbitrary positions . in the case of the example in fig2 , a finder image 26 of the object such as a tower block is displayed on the electronic display 21 , and for example , the vertical line 22 is moved to an arbitrary position in the lateral direction on the left portion of the finder image 26 by the switch 202 so as to be capable of being matched with the left end of the finder image 26 . similarly , the vertical line 23 is moved to an arbitrary position in the vertical direction on the right portion of the finer image 26 by the switch 203 so as to be capable of being matched with the right end of the finder image 26 . for example , when the perspective in the up - down direction is adjusted , the pinion 7 is pivoted by the operation knob 6 , so that the perspective in the up - down direction is adjusted to the optimal state . actually , when the operating knob 6 is pivoted so as to move the image pickup element 3 , only the finder image 26 is moved , and thus the direction of the optical axis of the camera should be changed . the vertical lines 22 and 23 are readjusted according to the adjustment state , and further may be finely adjusted by the operation knob 6 . fig2 illustrates a state in the middle of the perspective adjustment , and does not illustrate the complete adjusted state . in the complete perspective adjusted state , for example , an outline of the finer image 26 of the object such as tower block matches with the vertical lines 22 and 23 in parallel . similarly , when the perspective should be adjusted in the horizontal direction , the lateral lines 24 and 25 are matched with an upper edge and a lower edge ( upper end and lower end ) of the finder image 26 in the horizontal portion in the up - down direction . the operation knob 10 is operated so as to pivot the pinion 11 , and while the perspective in the horizontal direction is being visually checked , it may be adjusted to the optimal state . in this embodiment , the vertical lines 22 and 23 and the lateral lines 24 and 25 which are indicator lines are displayed as software display on the electronic display 21 , but the vertical lines 22 and 23 are independently move to arbitrary positions in the lateral direction on the entire surface of the electronic display 21 by the exclusive display operating section . this is applied also to the lateral lines 24 and 25 , and they are independently moved by the exclusive display operating section so that positions are adjusted . as a result , the indicator lines 22 to 25 are located with respect to the end portions of the finder image 26 , and the perspective state can be visually checked and adjusted . for this reason , visual check and adjustment can be carried out quickly and accurately . fig2 illustrates the case using a conventional liquid crystal screen for convenience of the explanation . it is , however , more preferable that a ferroelectric liquid crystal micro - display ( not shown ) is used as the finder so that the constitution may be similar to the state explained with reference to fig2 and the ferroelectric liquid crystal micro - display is magnified by a loupe . if necessary , a conventional liquid crystal screen is suitably used at the same time , thereby displaying an image . fig3 illustrates one example of a concrete constitution according to claim 3 of the present invention . a camera main body 31 has an image pickup element 32 on its inner surface on one side ( right surface or rear surface in fig3 ) ( the drawing and explanation of the finder and the other mechanisms are omitted ). a mount 35 having a constitution corresponding to a mount 36 of an interchangeable lens section 33 is mounted to the inner surface on the other side of the camera main body 31 ( left side or front side in fig3 ). a dustproof plate 34 made of glass or resin is fastened to the inner side of the mount 35 so as to prevent dust or the like from entering the camera main body 31 . an effect of the dust proof plate 34 is explained below . fig4 illustrates an imaging state of a projected image by means of a photographing lens 41 . as shown in fig4 , light beams , which are radiated from specified one point of an object and enter an entire aperture of the photographing lens 41 , are condensed to specified one point in a corresponding position to be an emission side if a distance to the object is farther than a focal length f of the photographing lens 41 . the light beams , which are radiated from the object 42 shown in fig4 and enter the photographing lens 41 , are , therefore , imaged as a projected image 43 in a specified corresponding position . when fig4 illustrates the imaged state by means of the photographing lens in the camera , the image 43 in fig4 is imaged on the image pickup element 32 in fig3 . as shown in fig3 , if dust 44 adheres onto the image pickup element 32 ( in fig4 , since it cannot be drawn with it overlapping with the image 43 , it is drawn in a position slightly close to the photographing lens 41 ), the image pickup element 32 captures the dust 44 directly as the image 43 . even a person who is not skilled in the art can understand this easily . if dust whose size is the same as the dust 44 is now present in a position designated by reference numeral 45 in fig4 , only a slight part of the light beams to be imaged as the image 43 is blocked . further , the light beam which is blocked by the dust 45 becomes a light beam in both directions towards a forward end and a base in an arrow direction of the image 43 in the drawing . that is to say , the entire image 43 is uniformly blocked , so that a specified portion of the image 43 is not blocked nor omitted . since the light beams which enter the entire aperture of the photographing lenses 41 from a specified point of the object 42 are condensed to one point in an imaging position , the incident light and the emitted light from the specified point of the object 42 are dissipated and converged into a conical shape . attenuation in a light amount due to the dust 45 becomes small in inverse proportion to the square of a distance from the imaging position ( position of the image pickup element 32 ). the dustproof plate 34 is , therefore , provided to a position shown in fig3 , so that a sealed structure is obtained . when the inside of the camera main body 31 is always kept in a clean state , even if the camera is used with slight dust adhering to the surface of the dustproof plate 34 ( an outer surface of the camera on the side of the photographing lens 41 ), an adverse problem hardly arises due to the adhesion of dust . the dustproof plate 34 is provided between the interchangeable lens section 33 and the camera main body 31 so that the camera main body 31 has the sealed structure , thereby preventing the dust from entering the camera main body 31 at the time of interchanging a lens . dust , therefore , does not adhere to the surface of the image pickup element 32 included in the camera main body 31 , and thus inappropriate photographing due to the adhesion of dust is prevented . further , even if the adhesion of dust and the contaminated state are terrible , the surface of the dustproof plate 34 just have to be wiped , so that the cleaning of dust is easy . the surface of the dustproof plate 34 may be hard coated for preventing scratch . it is natural the surface of the dustproof plate 34 is subject to a reflection preventing process . fig5 illustrates a constitutional example where a vent hole 53 that is communicatively connected to an external section ( atmospheric air ) of the camera main body 51 is formed on a side wall of the camera main body 51 and the closed - end cylindrical bellows 52 which is elastic is provided to an internal portion of the camera main body 51 corresponding to the vent hole 53 so that pressure of the vent hole 53 is applied thereto . with such a constitution , pressure outside the camera main body 51 is applied the vent hole 53 , and the bellows 52 extends and contracts elastically according to a pressure difference between the inside and the outside of the camera main body 51 . as a result , the pressure difference between the inside and the outside of the camera main body 51 is eliminated or is mitigated as quickly as possible by the elastic deforming function of the bellows 52 . element 54 designates the dustproof plate , such as a glass plate . fig6 illustrates a constitutional example where a vent hole 63 that is communicatively connected to the outside of a camera main body 61 is formed on one side surface of the camera main body 61 and a flexible thin plate ( for example , deflectable diaphragm having a shape of a lubricator bottom shape called as engine trumpet in japan ) or a resin screen 62 is attached to the inside portion of the camera main body 61 corresponding to the vent hole 53 so that pressure of the vent hole 63 acts . with such a constitution , the deflectable diaphragm or the resin screen 62 mitigates the pressure difference similarly to the bellows 52 shown in fig5 , so that the pressure difference between the inside and the outside of the camera main body 61 is eliminated or is mitigated as quickly as possible . element 64 designates the dustproof plate , such as a glass plate . according to the embodiments in fig5 and 6 , when the pressure difference occurs between the inside and the outside of the camera main body 51 or 61 , the flexible partitioning member 52 or 62 deflects , so that the pressure difference is mitigated or eliminated . even in the case , therefore , where the pressure difference is wide between the inside of the camera and atmospheric air due to temperature change , altitude change and the other weather conditions , strong external force can be prevented from being applied to the dustproof plate 54 or 64 . it is noted that the present invention can be variously modified unless such modification depart from the scope of the present invention and they should be construed as being included therein .