JPH04367807A - Lens barrel - Google Patents

Abstract

PURPOSE:To prevent photographic light from being eclipsed by the tip of the lens barrel at the time of close-up photography since the need for an external frame is eliminated and the lens barrel can be made short by providing a buffer material between a filter frame and the lens barrel. CONSTITUTION:A lens 1, the lens barrel 2, the filter frame 9, a decorative ring 10, and a zoom moving ring 3 move unitedly along the optical axis. The damper 12 for shock absorption is sandwiched between the lens barrel 2 and filter frame 9 and fixed with a filter frame fixing screw 13. Consequently, when an impact such as an external force of falling or snapping is applied to the tip part of the lens barrel from outside, the filter frame 9 receives the external force and the damper 12 absorbs the impact. Consequently, the external frame which is conventionally provided to protect the lens barrel is made unnecessary or reducible in size, so the quantity of the eclipse of stroboscopic luminous flux by the part of the lens barrel is reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel for a single-lens reflex camera.

0002

2. Description of the Related Art In recent years, many single-lens reflex cameras have built-in small strobes near the camera pentameter. This is because the strobe can be used easily and is considerably smaller than an external strobe, so it does not take up much space. However, single-lens reflex cameras use a variety of interchangeable lenses, so
When an interchangeable lens with a wide focal length is attached, the light beam of the camera's built-in strobe will be vignetted by the tip of the interchangeable lens, creating a semicircular shadow at the bottom of the film when shooting at close range, which may be unsightly. Ta.

[0003] In addition, the lens structure of wide-angle interchangeable lenses is generally of the type in which the front lens extends to focus, and the front lens at the tip of the lens, the front lens barrel, and its mounting part are protected from external forces such as drops and impacts. In order to protect the camera, a front aperture part called an outer frame is provided on the outer periphery of the camera, so the light beam of the built-in strobe of the camera is vignetted by the outer frame, causing the above-mentioned adverse effects.

The above-mentioned conventional lens barrel structure is shown in FIG. 2 and will be described below. Note that the lens barrel shown in FIG. 2 is an example of a zoom lens that covers a focal length up to the wide side. In FIG. 2, 1 is a lens group constituting a front group unit. A lens barrel 2 holds the lens group 1, and has a male helicoid 2a on its outer periphery. Reference numeral 3 denotes a zoom moving ring, which has a female helicoid 3a screwed into the male helicoid 2a on its inner periphery. Further, roller mounting holes 3b are provided toward the outer periphery. Reference numeral 4 denotes a zoom roller, which is fitted into the roller mounting hole 3b and fixed with a screw. is engaged, and the cam cylinder 6
Since the roller 4 rotates at a fixed position relative to the guide tube 5, when the cam tube 6 is rotated during zooming, the zoom roller 4 can move along the cam groove 6a in the optical axis direction. Reference numeral 7 denotes a focus helicoid, which has a male threaded portion 7a, and the focus helicoid 7 is fixed to the guide tube 5 by 7b. Reference numeral 8 denotes an outer frame, and a female helicoid 8a is formed at the rear of the inner periphery, and is threadedly engaged with the male threaded portion 7a. Furthermore, there is a straight groove 8b at the front of the inner circumference of the outer frame 8. Reference numeral 9 denotes a filter frame, and several protrusions 9a are provided on the outer peripheral side, and the protrusions 9a and the rectilinear groove 8b are engaged to be relatively movable in the optical axis direction. In addition, there is a filter mounting screw 9 on the inner tip side.
b, to which a filter (not shown) can be attached. 9c is connected to 2b of the lens barrel 2 and is integrated. 10 is a cosmetic ring, which is attached for the purpose of improving the appearance of the lens from the front side. 11 is a focus key, which is attached to a focus actuator (not shown);
1 is engaged with a notch 8c provided in the outer frame 8.

[0005] The focusing operation will now be explained. Focusing is performed by rotating the focus key 11 fixed to a focus actuator (not shown) around the optical axis, but since the focus key 11 is engaged with the notch 8c of the outer frame 8, Focusing is performed by rotating the frame 8 around the optical axis due to the engagement of the helicoids 8a and 7a, but since the focus key 11 is engaged with the notch 8c of the outer frame 8, the outer frame 8 is extended forward in the optical axis direction while rotating around the optical axis due to the engagement of the helicoids 8a and 7a. At this time, the filter frame 9 receives a rotational force due to the engagement between the straight groove 8b and the protrusion 9a of the filter frame 9, and the lens barrel 2, which is integrally supported with the filter frame 9, receives a rotational force due to the engagement of the helicoids 2a and 3a. It moves forward in the optical axis direction while rotating around the optical axis.

[0006] Here, the zoom movable ring is not extended forward of the optical axis due to zooming from the state shown in FIG.
In addition, helicoids 2a and 3a and helicoids 7a and 8
The leads of the two helicoids in a are the same, or the leads of helicoids 2a and 3a are smaller, so the tip of the filter frame 9 does not protrude beyond the outer frame 8, and even when an external force is applied to the tip of the lens, the lead is smaller. Since the external force is received by the frame 8 and transmitted to the guide barrel 5 via the focus helicoid, the important lens/lens barrel 2 will not be damaged.

FIG. 3 shows how the light beam of a strobe built into a camera is eclipsed by the tip of the lens. 1
9 is a camera body with a built-in strobe, and 19a represents the built-in strobe. 20 is an interchangeable lens barrel main body, and an outer frame 8 is provided at the tip thereof.

Line A-A is the optical axis of the lens, and the subject 21 is located in front of the interchangeable lens 20 on the optical axis. The subject 21
When trying to take a picture, if the amount of light is insufficient, the built-in strobe 19a compensates for the light emission, but the built-in strobe 19a
The light beam coming out from the top end is vignetted by the lens tip, and B-B
The light beam does not reach below the line. Similarly, the light beam emitted from the lower end of the strobe does not reach below the C-C line. Therefore, in the subject 21, there are roughly three areas where the amount of light 21a reaching from the strobe is sufficient, the amount of light 21b is almost insufficient, and the area 21c where the strobe light does not reach.

It is necessary to reduce the areas 21b and 21c mentioned above, that is, to reduce the diameter of the tip of the lens barrel 20.

0010

[Problems to be Solved by the Invention] However, as described above, when the interchangeable lens is attached to a camera with a built-in strobe and the lens is photographed at the wide-angle side, particularly at a close distance, the strobe light beam is vignetted by the tip of the lens. This has the disadvantage that a significant black shadow appears at the bottom of the film surface.

[0011] An object of the present invention is to provide a lens barrel constructed so as not to cause the above-mentioned vignetting.

0012

[Means for Solving the Problems] In the lens barrel of the present invention, a buffer material capable of absorbing impact and external force is interposed between the lens barrel and the filter frame, thereby protecting the conventional lens barrel. The present invention is characterized in that the amount of vignetting of the strobe light beam caused by the tip of the lens barrel is reduced by eliminating or shortening the outer barrel.

[0013]

[Embodiment] An embodiment of the present invention will be described below with reference to FIG. In the figure, 1 is a front group glass that is a part of the lens optical system, 2 is a lens barrel that holds the front group glass 1, 2a is a male helicoid provided on the outer periphery of the lens barrel, and 3 is a It is a zoom moving ring, and has a female helicoid 3a on its inner peripheral surface. 4 is a zoom roller, which is fixed to the zoom moving ring 3 with screws or the like. 5 is a guide tube;
5a is a straight groove provided in the guide tube 5. 6 is a cam cylinder, and 6a is a cam groove that determines the movement of the front group during zooming. 9 is a filter frame, and 10 is a decorative ring. 11 is a focus key that is attached to a focusing actuator (not shown) and rotates around the optical axis; 12 is a shock absorbing damper; and 13 is a filter frame temporary fixing screw. 14 is a hood attachment ring, and 15 is a dustproof sheet. Reference numeral 16 denotes a zoom operation ring, which is rotatably fixed to the cam ring and the optical axis by a zoom key (not shown). 17
18 is a zoom operation rubber, and 18 is a cam barrel fixing ring.

In the above configuration, the zoom position is set to the wide-angle side, and the zoom position is set on the cam barrel 6 which is rotatably supported by the groove 5a of the guide barrel 5 and the cam barrel fixing ring 18 relative to the guide barrel 5. The position of the zoom roller 4 is regulated by the cam groove 6a, and therefore the position of the lens 1, the lens barrel 2, the filter frame 9, the cosmetic ring 10, and the zoom moving ring 3 is controlled.
, damper 12, and filter fixing screw 13 move together along the optical axis. Therefore, the focus key 11 extending from a focusing actuator (not shown) rotates around the optical axis. An attempt is made to rotate the filter frame 9 to lens 1 together with the rotation around the optical axis, and the helicoid parts 2a and 3a rotate the lens 1, lens barrel 2, filter frame 9, cosmetic ring 10, damper 12,
The filter frame fixing screw 13 moves along the optical axis while being rotated by the lead of the helicoid, and a focusing operation is performed. Note that 14 is a member having a hood attachment groove for attaching the hood. 15, the filter frame 9 is moved to the zoom operation ring 1 by the above-mentioned focusing operation.
The feature of this embodiment is that the dustproof sheet moves in the optical axis direction with respect to the lens barrel 2 and the filter frame 9, so that it prevents dust etc. from entering the lens through the gap.
A shock absorbing damper 12 is sandwiched between both members, and the filter frame is fixed with a filter frame fixing screw 13. For this reason, when an external force is applied to the tip of the lens barrel from the outside, such as when it is dropped or hit, the force is received by the filter frame 9, and the shock is absorbed by the damper 12.
, the lens 1, the zoom moving ring 3, the zoom roller 4, and even the bevel groove 6a.

[0015]

As explained above, the lens barrel of the present invention provides the following effects. a. Since the conventional outer frame can be eliminated or downsized, the tip of the lens barrel can be made smaller by one part.

b. By a, it is possible to reduce vignetting of the strobe light beam when the built-in strobe is attached to the camera body.

c. A reduces the number of parts and reduces costs.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the main parts of an interchangeable lens barrel configured to apply the present invention.

FIG. 2 is a vertical cross-sectional view showing the main parts of a conventional lens barrel.

[Figure 3] Diagram showing the strobe light flux in the built-in strobe camera

[Explanation of symbols]

1... Lens (camera) 2... Lens front group barrel 2a... Male helicoid
3...Zoom moving ring 3a...Female helicoid
4...Zoom roller 5...Guide tube
5a... Straight groove 6... Cam tube
6a...Cam groove 7...Focus helicoid 7a...Male helicoid 8...Outer frame 8a...Female helicoid 8b...Straight groove
9...Filter frame 9a...Protrusion
10... Decorative ring 11... Focus key 12... Shock absorption damper 13... Filter frame fixing screw 14... Hood mounting ring

Claims (1)

[Claims] 1. A lens barrel detachable from a single-lens reflex camera, characterized in that a cushioning material is interposed in a member mounting portion provided at the tip of the lens barrel.