JPH02136839A - Camera having flange back adjusting mechanism - Google Patents

Abstract

PURPOSE:To realize a compact and simple constitution by providing an optical member capable of varying only an optical distance converted to air between a mounting surface on a camera main body side and an image pickup element. CONSTITUTION:A replaceable photographing lens 1 is mounted on the camera main body 2 side through a mount, and the object image light is guided to the surface of the image pickup element 11 by the photographing lens 1. The transparent optical member A is provided between the mounting surface 12 on the camera main body 2 side and the image pickup element 11: The optical member A is variable in optical axial thickness and capable of varying only the distance converted to air without varying the distance between the mounting surface 12 and the image pickup element 11. Consequently, by varying the optical axial thickness of the optical member A and adjusting a flange back on the camera main body 2 side, the flange back at the time of mounting the photographing lens 1 can be easily fitted in a prescribed amount. Thus, a compactly and simply constituted flange back adjusting mechanism can be obtained.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a camera having a flange back adjustment mechanism, and particularly to a camera that uses an image sensor such as a CCD, film, etc., and which has a flange back adjustment mechanism inside the camera body. It is possible to replace the IIT by adjusting the flange back on the camera body side. A compound that easily matches Fransiba and Tsuku when using a 141R shadow lens! 1? This invention relates to a camera having a flange back 7Ja machine bridge with an easy configuration.

(Conventional Technique #14) Conventionally, in cameras that have a 7-range bar adjustment mechanism that allows the photographic lens to be replaced, after combining the photographic lens attached to the camera body, the 1M image name is the photographic lens. I made two adjustments so that the plunge back of the camera and the flange back of the camera body side matched.

- Generally, cameras with interchangeable lenses have their optical system's focus setting and distance to the film plane determined based on the reference plane of the mount, and in many cases the optical axis and focus position are fixed. There is.

Therefore, if the flange focal length of the camera body and the 1111 lenses differ even slightly due to manufacturing variations, a focus shift or optical axis shift may occur, and the difference between the actual shooting distance and the distance adjustment ring of the shooting lens may occur. The displayed distance may be different from the displayed distance. In particular, the shorter the focal length of the lens, the greater the difference in this case.

Conventionally, this was done mainly by the photographer after the product was completed in order to match the flange back of the photographic lens and camera body. Moreover, the following three methods have been used as a mechanism for matching both flange backs at this time.

(a) A flange back adjustment mechanism is provided on the photographing lens side that moves part or all of the lens groups of the II shadow lens on the optical axis and changes the focal position relative to the mount surface.

(b) The camera body side has a flange back adjustment mechanism that can change the distance from the camera body side mount surface to the imaging surface.

(c) Manufacturing variations in both the flange back of the photographing lens and the camera body are suppressed to a level that does not affect the final output information of this camera system.

Figure M2 is a conventional example using the method (a), and is a schematic diagram of an optical system of a camera having a flange back adjustment mechanism within the photographic lens. In the figure, 21 is an interchangeable photographic lens (also referred to as an interchangeable lens), 22 is a camera body,
23 to 27 (: kli lens group constituting the shadow lens 21, 29 is a mount surface, and 28 is an image sensor.

In the figure, the lens group 27 in the photographic lens 21 is moved on the optical axis so that the focal plane of the photographic lens 21 is aligned with the camera body 22.
It is adjusted to match the imaging surface of the image sensor 28 inside.

In the method shown in the figure, consideration is given at the optical design stage so that the change in optical performance due to movement of the lens group is as small as possible and the back focus is changed as much as possible.

However, since some of the lenses constituting the photographic lens 21 are in the LT1 group, this method has limitations such as increasing the tolerance for optical axis misalignment, eccentricity, etc., making it difficult to make the camera more compact. It has been difficult to reduce costs.

FIG. 3 is a conventional example using the method (b), and is a schematic diagram of an optical system of a camera having a flange back adjustment mechanism in the mount portion of the camera.

In this figure, the same elements as those shown in Figure 182 are given the same reference numerals. 34 is a lens group constituting the photographing lens 21, and 33 is a camera-side mount section, which has an expansion 11il adjustment mechanism.

In the figure, the camera-side mount portion 33 is provided with a telescoping adjustment mechanism to adjust the flange back. That is, the distance from the mounting surface of the camera-side mount section 33 to the photographing element 28 is changed by the telescopic adjustment mechanism, and the photographing lens 21
The focal plane is adjusted so that it matches the photographed image of the image sensor 28 inside the camera body 22.

However, in the method shown in the figure, a movable mechanism must be provided at the joint between the photographic lens 21 and the camera body 22, which weakens the joint. As mentioned above, it was difficult to make the camera more compact and lower in cost.

Figure 4 shows a conventional example using method (b) above, in which the imaging surface of the image sensor is moved to achieve flange back! FIG. 2 is a schematic diagram of the optical system of the camera. In this figure, the same elements as those shown in FIG. 2 are given the same reference numerals.

In the same figure, Ijl image element z8 is 1111 lenses 21
camera side mount surfaces 29 and 11f by moving on the optical axis of
The distance between the FI elements 28 is changed to adjust the focal plane of the photographing lens 21 to match the imaging plane of the II image element 28 inside the camera body 22.

However, although the method shown in the figure is electrically easy for cameras that use an image pickup tube rather than a solid-state image sensor, it has recently become mainstream and when using a solid-state image sensor, the substrate itself must be moved along the optical axis. However, it was difficult to realize this because problems such as wiring and heat radiation were involved.

In addition, cameras that use multi-chip image sensors instead of single-chip cameras require moving a large glass block containing the resolving optical system along the optical axis, and as mentioned above, the aim is to make the camera more compact and cost-effective. It was difficult.

In addition, method (c) in Itij is a method generally used for *+a cameras, etc., and uses the minimum allowable complex 6 obtained from U, , and p of the silver-based camera as an annotation of the circle diameter. Within the capacity, there are 12 flange backs for both the camera body and the photographic lens.
It is constructed to accommodate the sum of manufacturing variations and errors.

However, recently, the density and miniaturization of solid-state image elements C have progressed, and movie cameras and SVs that use solid-state image sensors have been developed.
Cameras, etc. can have high resolution, and the minimum circle of confusion is permissible V.
They are also small and require extremely high precision. For this reason, it is necessary to adjust the flange back so as to expose the minimum amount of rust in the back of the solid-state image sensor only at the manufacturing stage, which requires a great deal of time and cost. It was difficult to do so.

For the reasons mentioned above, many cameras do not suffer from the above problem 1. There is a demand for a camera that is compact and has a plunge back adjustment mechanism that solves the IN problem.

(Problems to be Solved by the Invention) The present invention solves the problem of the problem between the mount surface on the camera body side and the image sensor (
By providing an optical member that can change only the optical air-equivalent distance, for example, using a transparent liquid or transparent elastic material with a variable thickness, it is possible to move the LJL shadow lens and the mount surface from the mount surface to the LIT image element or the like. To provide a camera having a flange back adjustment mechanism of a compact and easy configuration capable of easily matching the flange back of a camera body and the flange back of a photographing lens without changing the distance between the two.

(First step to solve the problem) Attach a convertible photographing lens to the camera body side via a flange, and capture the subject image using the photographic lens.
A camera that guides light to an image sensor surface 1- of a camera body side, and a distance between the Fran l-plane and the image sensor on the side of the camera body is set between the camera body side and the image sensor. By disposing a transparent optical member whose thickness on the optical axis is variable so as to change only the air ventilation distance without changing it, and by changing the thickness of the optical member on the optical axis, The flange back on the main body side can be adjusted.

(Example 'X) FIG. 1 is a schematic diagram of an optical system of a camera having a flange back adjustment mechanism according to an embodiment of the invention.

At the front, reference numeral 1 denotes an interchangeable photographic lens (also referred to as an interchangeable lens), which is mounted on the camera body 2.

3 to 7 are respective lens groups constituting the photographing lens l; 12
1 is a mount surface through which the photographing lens 1 is mounted and fixed on the camera body 2.

A is transparent IP with optical members and transparent plane plates 8 and 10.
1 has an elastic body and a general-purpose liquid 9, and the camera (only changes the air equivalent distance of 1 degree of light without changing the distance between the mount surface 12 on the body side and the lji image element 11) [7 lunge] Eight Tsuku? I'm making adjustments.

In other words, the line? The spacing between the face plates 8 and 10 is set at 8 (not shown).
8.It has a structure that makes it easy to change it depending on the stage.

The transparent liquid 9 (hereinafter referred to as transparent liquid J) is transferred to a transparent Y-type face plate 8. 11!49 g is held between the IO, and the peripheral part of the liquid 9 is covered with an elastic material such as silicone rubber. By changing the interval between the horizontal plane plates 89, the thickness of the transparent 1!1 liquid 9 along the optical axis is changed. Incidentally, numeral 11 is a Ptl pin, which is made up of, for example, a CCD or the like.

In this way, the optical axis L of the light '7' member A is
For example, if the thickness of the t line is changed by an external urging force, etc. Face plate 8
．． Interval of lO? By changing the light of transparent liquid 9 @
The thickness at l- is varied, thereby varying the optical air equivalent distance.

■! [In this embodiment, when the lil shadow lens 1 is installed on the camera body 2, lj! The flange back of the camera body 2 is adjusted by a flange back adjustment mechanism provided in the camera body 2 so that the flange back of the camera body 2 matches the flange back of the lens 1.

In the Northern Body system, as described above, the thickness of the transparent liquid 9 in the light Ml- is changed by changing the interval between the face plate 8 and IO using a biasing means (not shown), and the thickness of the transparent liquid 9 at this time is changed. The amount of change in is calculated using the following formula.

This allows #IA from the mount surface 12 on the camera body z side.
By changing only the air-equivalent distance of the optical member A without changing the distance to the image element 11, the focal plane of the photographing lens l matches the image plane II of the illumination elementary image 11 of the camera body 2, thereby preventing out-of-focus. For example, in this embodiment, the flange back of the taking lens 1 is longer than the flange back of the camera body z side due to the back N of the manufacturing E of the flange back of each of the taking lens 1 and the camera body 2. In order to match the flange backs of both sides, the thickness of the transparent liquid 9 on the optical axis is reduced by narrowing the interval between the horizontal plane plates 8 and 10 provided in the camera body 2 by a step 881 (not shown). do.

As a result, the air-equivalent distance of the optical member A changes, and the flange back on the camera body 2 side becomes optically longer than that at the time of manufacture, and can match the flange back of the photographic lens 1.

I can't stand it.

Amount of change in transparent liquid/thickness 4For example, if the refractive index n of the transparent liquid 9 is n=1.5, in order to increase the flange back on the camera body side by 0.1 mrn, the thickness of the transparent liquid 9 must be reduced by 03 mm from the above formula. Just do it.

In this way, in this example, an optical member is arranged between the camera body side mount surface and the image sensor that can change only the air equivalent distance without changing the distance between the camera body side mount surface and the image sensor. are doing. For example, even if manufacturing variations occur in the flange focal length of the photographic lens and camera body, the flange focal length of the photographic lens can be adjusted by changing the thickness of the optical distribution member on the optical axis. OT capability is to achieve a good match with the above.

Also, in the past, the amount of change in adjustment and flange back was just a turning value, so the flange back adjustment was, for example, 0.01 mm.
If the following high precision was required, it was necessary to use highly precise and expensive parts for the so-called VF mechanism, but in the present invention, using a transparent liquid with a refractive index of n = 1.5 is sensitive. The degree is 1/3, and the refractive index of transparent liquid is n-1,3, which is about the same as water.
If transparent liquid No. 3 is used, the sensitivity will be 1/4, allowing finer flange back adjustment with conventional mechanical accuracy.

In addition, when using a solid-state image element such as a CCD, optical components such as an optical low-pass filter and an infrared cut filter are required, but if these optical components are used as the IM transparent optical component, the light There is almost no additional space on the shaft for the flange back & II adjustment mechanism, and the layer can be made more compact. Furthermore, even when the photographic lens is a zoom lens, the camera operator can easily adjust the difference in back focus between the telephoto side and the wide side by incorporating the yl adjustment mechanism of the present invention.

(Effect of the invention) According to [1], only the optical air equivalent distance can be established between the camera body side mounting surface and the image sensor without changing the distance from the camera body side mounting surface to the IjI image element image element. By adjusting the flange back on the camera body side by changing the thickness of the 1m optical axis of the optical member, the flange back when a 1M shadow lens is attached can be reduced. It is a compact and IIIJX lens that can be easily matched to the specified value, does not place a large burden on the optical design of the ll shadow lens, and does not require strength reinforcement at the joint between the camera body and the ljI shadow lens. The flange back configuration is called S! It is possible to couple cameras with mechanisms.

[Brief explanation of the drawing]

Figure 1 shows an example of the Franchihauck style of the present invention! ! ! Figure 2 is a schematic diagram of the optical system of a camera that has a flange back adjustment mechanism in a conventional interchangeable lens. Figure 3 is a schematic diagram of a camera optical system that has a flange back adjustment mechanism in a conventional interchangeable lens. No. 41A is a schematic diagram of an optical system of a camera having a foot adjustment mechanism. No. 41A is a schematic diagram of an optical system of a camera in which the flange back is adjusted by moving the imaging surface of a conventional illt element. In the figure, l is a photographing lens (interchangeable lens), 2 is a camera body, 3 to 7 are lens groups, A is an optical member, 8410 is a fixed transparent optical member, 9 is a transparent liquid optical member, it is illll elementary image, 12 is a mounting surface, and 13 is a transparent elastic body. Watch applicant Canon Co., Ltd. agent Yukio Takanashi: ・１、）□、′−、−
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Claims (1)

[Claims] (1) Attach an exchangeable photographic lens to the camera body side via a mount, and capture the subject image using the photographic lens using CC.
A camera that guides light onto an image sensor surface such as D, in which only an air equivalent distance is provided between the mount surface on the camera body side and the image sensor without changing the distance between the mount surface and the image sensor. A transparent optical member having a variable thickness on the optical axis is arranged so as to change the thickness of the optical member, and the optical flange back on the camera body side is adjusted by changing the thickness of the optical member on the optical axis. A camera having a flange back adjustment mechanism.