JPS61156109A - Auxiliary telephoto lens device - Google Patents

Abstract

PURPOSE:To obtain a low-cost and clear high-magnification auxiliary telephoto lens device, by providing a Keplerian lens composed of a front lens group and rear lens group. CONSTITUTION:An auxiliary telephoto lens device 1 is composed of a front lens barrel 1a connected with a rear lens barrel 1b by means of a helicoid screw 3 under a rotation-free condition and the rear lens barrel 1b and a cemented lens, in which a positive lens 41 and negative lens 42 are cemented to each other, and a front lens group 4 composed of a negative lens 43 and positive lenses 44 and 45 are assembled in the front lens barrel 1a. A rear lens group 5 composed of a negative lens 51 and cemented positive lens of positive lenses 52-54 are assembled in the rear lens barrel 1b. The rear lens barrel 1 is fixed to a camera 2 by means of a fitting screw 8 by utilizing a screw seat for tripod so that a finder hood 6 and exposure correcting prism 7cn be made to correspond to the finder 21 and automatic exposure sensor 22 of the camera 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a telephoto auxiliary lens device for a lens-shutter type camera.

(Problems to be solved by conventional technology and invention) 135
A lens-shutter camera that uses film is simpler,
Its popularity has been increasing in recent years due to its portable ratio and quick shooting ability.

Beginners generally do not have the skills to master high-end cameras (e.g., reflex cameras). In addition, people currently prefer lens-shutter cameras, which are relatively cheap in price, and they are easy to use, convenient to carry, and have telephoto effects similar to those of reflex cameras. I often want photos that show off my personality.

However, this popular camera also has its weaknesses. In other words, since the camera uses a lens that is classified as a wide-angle lens with a focal length of about 30 to 35 inches,
Snapshots of people at close distances of meters can be taken relatively well, but when photographing small objects from medium to infinity distances, the disadvantage is that the objects appear very small in normal prints, making it difficult to distinguish the subject. have.

Conventionally, therefore, a method has been taken to increase the focal length by attaching a Galileo-type telephoto auxiliary lens mount [1-] directly in front of the photographic lens.

However, in this camera, in order to compensate for the inaccuracy in focusing ζ by using the so-called wide-angle lens' focusing effect, and to make the camera body smaller and lighter, the lens had a relatively short focal length. When using a short wide-angle lens and the camera is an autofocus/autoexposure type, 1. Normally, the autofocus/auto-no-output unit uses behind-the-lens-shutter, so the percentage control is different from that of the lens group. Since it is located at the rear, the entrance pupil is deep.

Therefore, if a Galileo-type telephoto auxiliary lens device is attached in front of the lens group, the entrance pupil will become deeper, so unless the effective diameter L of the telephoto auxiliary device lens is made large enough, the luminous flux around one frame will be reduced. The drawback is that it is difficult to secure.

For this reason, the Galileo-type telephoto auxiliary lens devices currently sold on the market have a diameter of about 1.2 mm and hardly function as a telephoto auxiliary lens. Of course, it is possible to design and manufacture a vertical Galileo-type telephoto auxiliary lens device with a magnification of about 1.5 times, but the outer diameter is very large, the IIM is heavy, and the cost is high (as it has little practical value as a product). It's not easy.

(Purpose of the invention) The present invention helps to solve the above technical problems.

To provide a telephoto auxiliary lens device which can be attached to a lens-shutter type camera to take a clear high-magnification telephoto photograph at a low cost with a magnification of 1.5 times or more, 3 times or 5 times, and without Keppler in the principal ray. This is the entire purpose.

(Elaborate Means for Solving the Problems) The present invention solves the above technical problems by providing a Keplerian lens consisting of a front group lens and a rear group lens. Then, the front lens group is made movable, and the aperture F value is set to the aperture F' of the camera's photographing lens.

This provides a telephoto auxiliary lens device that is lightweight and highly portable.

In other words, by making the lens structure Keplerian, it is placed in front of the F-injection III, and when the magnification becomes higher, the aperture F value of the telephoto auxiliary lens device is limited, making it possible to make the lens smaller and lighter. Next.

First, the problem with a Keplerian-type lens configuration is that
Unlike normal shooting, the image recorded on the film surface is an inverted image. However, with lens-shutter cameras, the photographing lens system and finder optical system are separate systems, so there is no problem with photography. In other words, even if it becomes an inverted statue with the top and bottom upside down.

When viewing photographs as prints or slides, it is sufficient to rotate the film 180 degrees, so there is no practical problem.

The next problem is that the farthest photographing distance of the photographing lens of a lens-shutter type camera is set at about 5 to 11 meters, and intermediate distances are also set roughly. This is a ninety-nine shot that focuses on close-up photography, uses a wide-angle lens, and uses the nine-pan focus effect. Therefore, if the amount is about 1.2 times the conventional amount, it will not be much of a problem.

In the case of a telephoto auxiliary lens device with a high magnification such as 5x or 2x, a clear image at a long distance can be obtained.
Even at intermediate distances, a clear image with a shallow depth of field can be obtained.
l - The image side or film surface 9111K is resolved by moving.

The next problem is that it is not a problem when the magnification is about 2x, but when the magnification is 3x or 5x, even if a 9 o'clock Keplerian type lens configuration is adopted, the telephoto auxiliary lens device becomes large and becomes an obstacle to the 7-lens infra system. However, in the case of an autofocus or autoexposure type camera, it will interfere with the distance measurement device and photometer neck. This is in the case of a telephoto auxiliary lens device that covers the entire brightness of the camera's photographing lens, and as is well known, the effective diameter of the lens is determined by the ratio of the focal length and the aperture f-number.
By setting the camera's aperture to a dark aperture, the outer diameter of the telephoto auxiliary lens device can be made smaller. The depth becomes deeper and the range of focus becomes wider. However, if the aperture P value of the telephoto auxiliary lens device is set to too low (this will cause an error in the camera's exposure and it will not be possible to obtain the correct exposure.Of course, in the case of manual exposure, this can be corrected at the time of shooting, and the aperture value remains constant even with automatic exposure. With a method where the shutter speed is changed or a method where the shutter speed is constant and the aperture value is changed, correct exposure can be obtained by correcting the brightness in the automatic exposure sensor.However, if the aperture value and In the case of the so-called programmed type where the shutter speed changes together, errors occur in the old correction.Here, we focus on the fact that even if the image plane exposure is usually one step higher, it is still within the latitude range of the film. By setting the brightness of the telephoto auxiliary lens device one to two steps darker, and correcting the difference in brightness between the photographing lens and the telephoto auxiliary lens device by 172 degrees, the outer diameter of the F device was downsized, and automatic string extraction was performed. It is possible to keep the correction error within the allowable range and easily perform aberration correction IE.If the telephoto auxiliary lens device is attached to a camera with an aperture of F2.8, the aberration correction error can be kept within the allowable range. 4~F'/
5.6, but since telephoto shooting is mainly for out-of-order shooting, there is no problem with brightness.

The most important problem is that the angle of view changes due to the use of a telephoto auxiliary lens device, making it necessary to change the field of view. Traditionally, this field of view change has been done by placing a screen just in front of the viewfinder to narrow the field of view, or by indicating it with a field frame. Even if you do K eventually, there will be a problem that the camera will get wet when you do it right in front of the viewfinder and it will be hard to see. In the present invention.

The field of view of the F-finder was changed by installing a finder hood. For hood type.

Compared to methods such as using a close-up mask, where the boundary determined in the field of view is placed just before the viewfinder, it is easier to see, and at the same time, the effect of TwoP (tlcL9) and the entire subject can be seen clearly.

(Example) An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows the configuration of an embodiment, in which numeral 1 is a telephoto auxiliary lens device according to the present invention, and 2 is an autofocus/automatic extension type lens shutter camera.

The telephoto auxiliary lens device 1 includes a front lens barrel 1M rotatably screwed together with a helicoid screw 3 and a vk lens barrel 1b, and the front lens barrel 1mK includes a positive lens 41 and a negative lens 42.
A front group lens 4 consisting of a nine cemented lens, a negative lens 43 and a positive lens 44.45 is built into the rear lens barrel 1b, and a cemented positive lens consisting of a negative lens 51 and a positive lens 52, 53, 54 is built into the rear barrel 1b. A rear group lens 5 consisting of the following is incorporated. The rear lens barrel 1b is mounted using a tripod screw socket so that the finder hood 6 and exposure compensation prism 7 face the finder 21 and automatic exposure sensor 22 of the camera 2. Fixed.

FIG. 2 shows the lens configuration of the example. Assuming that the own radius Qrl~r17, the thickness of the center of the lens, and the distance between the lenses are d1~d16, respectively, the specifications of this Shinzu yarn are as shown in Table 1.

Note that nd is the refractive index, and νd is the optical number.

1st table ν d nd νd 126.33007.16001.6968055.5
2 -26.3300 1.1600
1.805 Seal 8 25.53-269.50
0021.2300 4-15.08001.20001.48?4970.
4535.00009.570G 6-23.79005.35001.8466623.
87-16.78000.1500 816.78005.35001.8+66623.8
923.790012.4300 10-18.81001.9700 f, 784722
5.71139-01004.0000 12-26.75006.050G 1.620416
0.313-15.84000.1500 1445.97005.77001.6988055.
515-45.97000.1500 1626.70005.96001.5891361.
317N411600 FIG. 3 is a program diagram showing the relationship between the shutter speed and the aperture value when the automatic exposure lens shutter type camera with an open F value of F'/2.8 is set to ASAloo.

From this program diagram, when attaching the telephoto auxiliary lens device to the camera, there is a misalignment when using the camera alone! In the case of a telephoto auxiliary lens device with an open F value of I'/4, the open F value is 1 aperture D 1rlt (1 gV), so the automatic repair sensor correction 1t - tl - 0.5 aperture open ( After such correction, the result will be as shown in Table 2.

When the external light is EIV7, the appropriate aperture value and shutter speed are aperture value F'/2.8 and shutter speed @: 1/16 seconds. However, the camera's automatic exposure sensor has a +0.5
Since the EI V is being corrected, the camera side is l1iv.
6.5 photoelectric, and the aperture value is F'/2.8. The shutter speed is set at IJjl/12 seconds. However, since the aperture P value of the telephoto auxiliary lens device is I'/4, in reality, the aperture P value is F/4 and the shutter speed is 1/12 seconds to clear the path light, so the combination is B V This setting is suitable for external light of 7.5. The error from this carefully determined appropriate exposure is -0.5
gV.

FIG. 4 shows the relationship between the distance error and the change in external light. In this way, it is possible to suppress the automatic exposure correction error within an allowable range.

Oh, what's the open F value? / In the case of a telephoto auxiliary lens device of 5.6, the correction tt-1 aperture opening (by making a correction, it is possible to suppress the tolerance to +1 stop @4 as shown in Table 3).

The 7hM output correction member corrects the light amount using an ND filter or the like. And if the telephoto auxiliary lens device is not going to be in the shadow of this automatic repair sensor, will it have a density equivalent to an ND filter? A prism can be used.

Finder 7-)'6 is finder-21! Depending on the physical condition of the subject, it is configured so that it is enlarged by telephoto shooting and overlaps with the next frame. In addition, the F photographer can know which part of the subject is being photographed, and at the same time can ensure that the subject is clear and free of internal reflections within the viewfinder.

(Effects of the Invention) As described above, by employing the Kepler-type lens configuration, high-magnification telephoto photography has become possible.

This is impossible with the conventional Galileo-type telephoto auxiliary lens device, and by suppressing the maximum aperture F value to +2 stops or less, in other words, by setting the aperture to %0, ~ +2 steps darker, it is possible to improve practicality. It is possible to provide a complete telephoto auxiliary lens device with a high magnification, allowing photographers to take pictures over a wide range.

4. Figure 1 CD-Ran Rate Explanation Figure 1 is a cross-sectional view of an embodiment of the present invention, Figure 2 is an explanatory diagram showing the lens configuration, and Figure 3 shows the relationship between the aperture value and shutter speed change of the automatic exposure power mechanism. Program diagrams shown in Figures 4 and 5
Each figure is a graph showing the error with respect to the brightness of each subject by -4.

1...Telephoto auxiliary lens device, 2...Auto-focus/auto-exposure type lens shutter camera.

Patent applicant: Sigma Co., Ltd. Figure 1 Figure 2 Figure 4 Esu Figure 5 Figure 3 - Tehiro 4 (-ichiichichuu)

Claims (5)

[Claims] (1) A telephoto auxiliary lens device for a lens shutter type camera, characterized in that it is equipped with a Keplerian type lens consisting of a front group lens and a rear group lens. (2) A telephoto auxiliary lens device according to claim 1, in which the front group lens is movable back and forth. (3) +2 from the aperture f-number of the camera lens to be attached
A telephoto auxiliary lens device according to any one of claims 1 to 2, characterized in that the aperture F value is set to be darker than a step. (4) A telephoto auxiliary lens device comprising a Kepler type lens consisting of a front group lens and a rear group lens, and an incident light correction means for an automatic exposure control sensor of a camera to which it is attached. (5) A telephoto auxiliary lens device comprising a Keplerian lens consisting of a front group lens and a rear group lens, and a finder hood that also serves as a field frame for field conversion at a position relative to the viewfinder section of the camera to which it is attached. .