JPH04269727A - Camera - Google Patents

Abstract

PURPOSE:To obtain optimum image quality with respect to various kinds of screens by providing a diaphragm aperture corresponding to plural screen sizes on the image forming lens system of a camera and selecting the size and shape of a diaphragm according to the screen size. CONSTITUTION:Photographing lenses 16a-16e are disposed on a photographing optical path 27, a diaphragm aperture plate 28 and a shutter 29 are provide between the photographing lenses 16b and 16c. Diaphragm apertures 28a-28d which are selected and used according to the setting of the screen size and wedge-shaped grooves 28e-28h corresponding to respective diaphragm apertures, are provided on the diaphragm aperture plate 28, so that the diaphragm aperture is fixed on the photographing path 27. One end of the diaphragm aperture plate 28 is set to a screen size setting member 19, and it is slid to fix the selected diaphragm aperture on the photographing optical path 27. Especially, on a panorama screen having a large aspect ratio, the diaphragm is made into an ellipse, the short side of the ellipse corresponds to the long side to the picture, and the major axis corresponds to the short side of the picture, so that a longitudinally/latitudinally uniform image can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera, and more particularly to an aperture of an optical system thereof.

0002

[Prior Art] Generally, in an optical system, it is desirable that each light ray that passes through the optical system and forms an image of an object satisfies ideal imaging conditions, but in practice this is not possible and aberrations are prevented. What happens is inevitable. Aberrations increase as the position of light rays passes from the vicinity of the optical axis, so in an optical system, an aperture is used to obtain a good image by limiting the area around the optical axis through which light rays can pass. It is set up.

[0003] Cameras are also equipped with an aperture to limit the light passing through the lens within a certain range centered on the optical axis when photographing a subject, thereby minimizing aberrations in the formed image and producing good images. I'm trying to get it. However, the outer edges of the image have larger aberrations than the center, resulting in lower image quality and illuminance, so the aperture is determined according to the size of the screen frame. Although this screen frame is also a diaphragm in a broad sense, the diaphragm in this specification refers to an aperture means that limits the area of light rays passing through the above-mentioned optical system.

[0004] Here, the relationship between the aperture size of the diaphragm, image quality, and amount of light will be explained. FIG. 1 shows a diaphragm with a large aperture, and FIG. 2 shows a diaphragm with a small aperture. Each optical system is an imaging lens system consisting of three lenses. Figure 1
In this case, there are a convex lens 2a and a concave lens 2b from the subject side, and an aperture 1 is provided between them and the next convex lens 2c. Similarly, in FIG. 2, there are a convex lens 4a and a concave lens 4b from the subject side, and a diaphragm 3 having an aperture smaller than the aperture of the diaphragm 1 is provided between the convex lens 4c and the next convex lens 4c. Aperture 1
, 3 are all circular. The relationship between the distance from the optical axis, the image quality, and the amount of light in the optical systems shown in FIGS. 1 and 2 is shown in FIGS. 3 and 4, respectively. The image quality near the optical axis of the image is designed so that it hardly changes depending on the aperture size, but at the outer edge of the image, aberrations become large at the aperture 1, which has a large aperture.
This is lower than the aperture 3, which has a smaller aperture. Furthermore, although the amount of light is greater with a diaphragm with a larger aperture, vignetting occurs at the outer edge of the image due to the diameter of the lens, and the illuminance is greatly reduced compared to the center. As can be seen from Figures 3 and 4,
With aperture 1, which has a large aperture, the image quality and illuminance deteriorate significantly at the outer edge of the image, and as shown in FIG.
is the permissible range 6 of image quality illumination reduction for aperture 3 with a small aperture (Fig. 6
). Usually, in a camera with a fixed aperture diameter, the screen frame described above is provided with only one circular aperture having a size that falls within the allowable range for lowering image quality and illuminance. That is, when an image size 7 is required in FIG. 6, the diaphragm 3 must be large enough to ensure the permissible range 6 for lowering the image quality and illuminance.

[0005]

[Problem to be Solved by the Invention] However, when shooting images with a large aspect ratio, such as a so-called cropped screen or a panoramic screen, which is cut from the largest screen frame using the same camera, it is necessary to If the aperture is sized to fit the image, the image quality of the formed image remains at its maximum. When cropping or panorama shooting, the required image size is smaller than the maximum screen frame, so by changing the aperture size of the aperture, the image quality of the required size image can be improved. However, since the aspect ratio of a panoramic screen is large, it is difficult to obtain good image quality by considering both image quality and illuminance using a circular aperture.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a camera having an aperture that can obtain the best image quality even for cropped images and panoramic images.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a selection means capable of selecting an arbitrary screen shape from a plurality of screen shapes, and a selection means arranged in a photographing lens according to the selection of the selection means. In particular, in the case of a screen frame having a rectangular aperture with a large aspect ratio and arranged on the imaging plane of the photographing lens,
An aperture disposed within the photographic lens having an aperture shape that is large in the direction of the short side of the screen frame and small in the direction of the long side is selected.

[0008]

[Operation] By doing so, by using, for example, an elliptical aperture in a camera dedicated to panoramic photography, good image quality can be maintained on both the long and short sides. Also,
When shooting multiple screen sizes with the same camera, including panoramic screens, you can choose the size and shape of the aperture that will give you the best image for the required image size on the film. High image quality is guaranteed regardless.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 7 shows the configuration of a camera dedicated to panoramic photography. Mechanisms such as film attachment and flash will be described in detail in another embodiment, so only the optical system will be described here. Convex lens 8a and concave lens 8b as photographic lenses
, convex lenses 8c are arranged side by side on the photographing optical path 9, and between the concave lens 8b and the convex lens 8c there is an elliptical aperture diaphragm 10 whose short axis corresponds to the long side of the panoramic screen and a long axis corresponds to the short side, and a shutter. 11 are provided. On the photographing optical path 9, a panoramic screen frame 12 with a larger aspect ratio and a film 13 are installed behind the panoramic screen frame 12.

The reduction in image quality and light intensity at a position away from the vicinity of the optical axis of the optical system is the same in any direction from the optical axis with a circular aperture as shown in FIGS. 5 and 6, but with an elliptical aperture In the case of the aperture, the aperture direction is different in the a-section direction and the b-section direction, as shown in FIG. The amount of light is A/B times that of the aperture B on the optical axis (near h0). The image quality in the cross-sectional direction a is equivalent to that of the circular diaphragm of the aperture A, and in the cross-sectional direction b is equivalent to that of the aperture B. That is, since the deterioration in image quality and light intensity is more remarkable in the a-section direction, the elliptical diaphragm 10 is installed so that the a-section direction corresponds to the short side of the screen frame, and the b-section direction corresponds to the long side of the screen frame. There is. FIG. 9 shows an elliptical aperture 10 in an optical system configured as shown in FIG. 7, an allowable range 14 for reducing image quality and illuminance due to the aperture 10, and a panoramic screen 12. The elliptical diaphragm 10 has a major axis equivalent to the large diameter diaphragm 1 in FIG. 5, and a minor axis equivalent to the small diameter diaphragm 3 in FIG.
The image quality illuminance reduction tolerance range 14 is a combination of the tolerance range 5 in FIG. 5 and the tolerance range 6 in FIG. 6, and also has an elliptical shape. A small aperture on the long side of the panoramic screen prevents vignetting, and a large aperture on the short side to ensure a sufficient amount of light while minimizing deterioration in image quality and ensuring uniform image quality horizontally and vertically.

Next, another example will be shown. FIG. 10 shows a perspective view of a camera that can set a plurality of screen sizes. The camera body includes a photographing lens 16 and its window 17, a finder camera front window 18, a screen size setting member 19, a screen size setting indicator 20, a flash device 21, a film cartridge storage chamber lid 22, and a film winding knob 23.
and a release button 24 are provided, and the flash device 21 is provided with a flash emission window 25 and a flash charge button 26.

The user first opens the lid 22 of the film cartridge storage chamber to store a film cartridge, which will be described later, and operates the film winding knob 23 to set a photographic frame on the film. Next, the screen size is set by aligning the screen size setting member 19 with the screen size setting index 20 according to the scene to be photographed. In the same figure,
It is set to "PAN" mode (panorama mode). Furthermore, when it is desired to perform flash photography, the energy required for light emission can be charged by holding down the flash charge button 26 for a predetermined period of time. Thereafter, by observing the subject through an eyepiece window (not shown) behind the camera in the finder and pressing the release button 24, photographing at a predetermined screen size is executed. If the flash is charged at this time, the flash fires and flash photography is executed.

FIG. 11 shows the internal configuration of the camera shown in FIG. Although FIG. 11 corresponds to FIG. 7, a mechanism for setting the screen size is added. Photographing lenses 16a, 16b, and 16c are arranged on the photographing optical path 27. A diaphragm aperture plate 28 and a shutter 29 are provided behind the aperture plate 28 between the photographing lenses 16b and 16c. The diaphragm aperture plate 28 includes:
In order to fix the aperture apertures 28a, 28b, 28c, and 28d and the aperture apertures at a predetermined optical position, that is, on the photographing optical path 27, a wedge-shaped groove 28 is provided corresponding to each aperture aperture.
e, 28f, 28g, and 28h are provided. One end of the diaphragm aperture plate 28 is engaged with a screen size setting member 19, and by sliding and operating the screen size setting member 19, the diaphragm aperture is selected and the tip 30a of the spring 30 is inserted into the groove. The selected aperture aperture is fixed on the photographing optical path 27. In the same figure,
The screen size is set to "NORMAL", the spring 30 is engaged with the groove 28e, and the aperture aperture 28a is aligned with the photographing optical path 27.
Fixed on top.

A screen frame 31 on the photographing optical path 27 defines the entire screen reflected on the film 32 when the screen size is set to "NORMAL". The film 32 is housed in a film cartridge 33, and when the film cartridge 33 is set in a camera, a winding mechanism 34 pulls the film 32 onto a spool 35, although this is not particularly necessary.
The entire film is wound up, and then one frame is transferred to the film cartridge 3 each time a picture is taken via the transmission mechanism A.
Rewind to 3.

The above-mentioned shutter 29 usually uses a film 32.
The photographing optical path 27 is blocked in the middle to prevent exposure, but when the press of the release button 24 is transmitted by the transmission mechanism B, the photographing light is allowed to pass for a predetermined exposure time. At this time, a trigger signal for flash emission is transmitted to the flash device 21a via the transmission mechanism C at a predetermined timing.
sent to. As described above, if the flash is charged by the flash charge button 26, it will immediately emit light in response to the trigger signal.

The screen size writing device 36 receives information about the screen size set by the screen size setting member 19 from the transmission mechanism D, and also receives a signal linked to rewinding the film one frame after shooting from the transmission mechanism E. The photographed screen size is written at a predetermined position on the film 32. Writing is performed by mechanical, magnetic, or electromagnetic means, and the information determines the usable range within one frame of the film when printing on photographic paper.

FIG. 12 shows the film 32 and the actual image areas of each screen size. The film 32 is housed in a film cartridge 33, and there are rectangular holes 37 between each frame. Set the screen size setting member 19 to "NORMA"
When set to "L", the aperture aperture 28a is selected, and the image area of the film 32 becomes the same as the maximum image area defined by the screen frame 31, which is the actual use image area 38 in FIG. Similarly, in the setting of "PAN", the aperture aperture 28b is selected and the actual usable image area on the film 32 is 39. With the "TRIM1.4" setting, the aperture aperture 28c is selected and the actual use image area on the film 32 is 40, and with the "TRIM2" setting, the aperture aperture 28d is selected and the actual use image area on the film 32 is 40. The area is 41. This screen size information is written onto the film 32 by the above-mentioned writing device 36, and determines the range of the image to be used when forming the image on photographic paper or the like. Therefore,
If you take a cropped photo, the magnification will be higher than when you take a full-frame photo, and panoramic photos will give you a wide field of view.

[0018] Figures 13 to 16 show, for each screen size,
Shows the aperture aperture and the screen in actual use. In FIG. 13, when the screen size is set to "NORMAL", the diaphragm aperture 28a is selected for the lens 16, the tip 30a of the spring 30 engages with the groove 28e, and is fixed on the photographing optical path 27. . "N
ORMAL, the actual screen is the entire area defined by the camera's screen frame 31, and a circular aperture 28a with the smallest diameter is used to ensure image quality in this area.

In FIG. 14, the screen size is set to "PAN", the aperture 28b is selected for the lens 16, the tip 30a of the spring 30 is engaged with the groove 28f,
It is fixed on the photographing optical path 27. The actual use screen 39 in "PAN" has a width that is almost the same as the screen frame 31 of the camera, but a small vertical width and a rectangular shape with a large aspect ratio, so an elliptical aperture 28b is used. This oval aperture 2
8b has a short axis parallel to the long side direction of the screen 39, a long axis parallel to the short side direction of the screen 39, and the size of the short axis is almost equal to the diameter of the aperture 28a in the above-mentioned "NORMAL" mode.
The length of the major axis is approximately equal to the diameter of the aperture 28d in "TRIM2", which will be described later.

In FIG. 15, the screen size is "TRIM1.
4", and the aperture aperture is 2 for the lens 16.
8c is selected, and the tip 30a of the spring 30 is engaged with the groove 28g and fixed on the photographing optical path 27. “TRIM1.
The actual use screen 40 in "4" is smaller than the screen frame 31 of the camera, and the angle of view with respect to the lens 16 is also smaller.
Aperture aperture 2 larger than aperture 28a during “NORMAL”
Even if 8c is used, the image quality will not deteriorate and the amount of light will increase.

In FIG. 16, the screen size is "TRIM2".
The aperture aperture 28d for the lens 16 is
is selected, the tip 30a of the spring 30 is engaged with the groove 28h, and is fixed on the photographing optical path 27. The actual usage screen 41 of “TRIM2” is the actual usage screen 4 of “TRIM1.4”.
Since it is possible to use the aperture aperture 28d which is smaller than 0 and therefore even larger than the aperture 28c of "TRIM1.4", it is possible to make the image brighter.

In the explanation so far, high image quality has been achieved by changing the size and shape of the aperture aperture depending on the screen size, but it is possible to obtain clearer images by making the shutter speed variable in combination with the aperture. can. "T
When setting ``RIM1.4'' or ``TRIM2'' to use a large aperture aperture, or when you can secure a sufficient amount of light, such as when using flash photography, you can increase the shutter speed to compensate for the brightness and prevent subject blur and blurring. It can reduce blur and improve image quality.

[0023]

[Effects of the Invention] As explained above, according to the present invention,
In the case of a screen with a large aspect ratio such as a panoramic photo, you can use an oval aperture with a small aperture on the long side of the screen to prevent vignetting, and a large aperture on the short side to ensure the amount of light. Reduces deterioration in image quality and provides uniform image quality horizontally and vertically. In addition, as shown in another example, by simply setting the screen size by sliding the operating member provided on the camera housing, the plate-like member provided with the aperture that matches the screen size will slide. , the best sized and shaped aperture of the multiple screen sizes is selected as the aperture. Therefore, for all screen sizes that can be set, high-quality photographs with less decrease in illuminance at the outer edges can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical system with a large-diameter aperture.

FIG. 2 is a diagram showing an optical system having a small diameter aperture.

FIG. 3 is a diagram showing the relationship between the distance from the optical axis of a large-diameter aperture, image quality, and light amount.

FIG. 4 is a diagram showing the relationship between the distance from the optical axis of a small-diameter aperture, image quality, and light amount.

FIG. 5 is a diagram showing a large aperture aperture and the allowable range of image quality and illuminance.

FIG. 6 is a diagram showing a small aperture diaphragm and an image quality illuminance tolerance range.

FIG. 7 is a diagram showing the configuration of a camera dedicated to panoramic photography.

FIG. 8 is a diagram showing the relationship between the distance from the optical axis of an elliptical aperture, image quality, and light amount.

FIG. 9 is a diagram showing an elliptical aperture and an image quality illuminance tolerance range.

FIG. 10 is an external perspective view of a camera that can set multiple screen sizes.

FIG. 11 is a diagram showing the configuration of a camera that can set multiple screen sizes.

FIG. 12 is a diagram showing a film and an actual screen of each screen size on the film.

FIG. 13 is a diagram showing the aperture aperture and the actual screen when the screen size is set to “NORMAL”.

FIG. 14 is a diagram showing the aperture aperture and the actual screen when the screen size is set to “PAN”.

FIG. 15 is a diagram showing the aperture aperture and the actual screen when the screen size is set to “TRIM1.4”.

FIG. 16 is a diagram showing the aperture aperture and the actual screen when the screen size is set to “TRIM2”.

[Explanation of symbols]

10, 28a, 28b, 28c, 28d Aperture aperture 8
a, 8b, 8c, 16a, 16b, 16c Photographing lens 11, 29 Shutter 12, 31 Screen frame 13, 32 Film 19 Screen size setting member 20 Screen size setting index 28 Aperture aperture plate 30 Spring 36 Writing device

Claims (4)

[Claims] 1. A photographic lens, a screen frame having a rectangular aperture with a large aspect ratio and arranged on an imaging plane of the photographic lens, and an aperture shape that is large in a short side direction and small in a long side direction of the screen frame. and a diaphragm disposed within the photographing lens. 2. The camera according to claim 1, wherein the aperture is elliptical. 3. A photographic lens, a selection means capable of selecting an arbitrary screen shape from a plurality of screen shapes, and a variable lens that changes the aperture shape of a diaphragm disposed within the photographic lens according to the selection of the selection means. A camera comprising means. 4. When the selection means selects a rectangular screen shape with a large aspect ratio, the variable means makes the aperture shape of the diaphragm larger in the short side direction of the rectangle and smaller in the long side direction. The camera according to claim 3, characterized in that: