JPH0497325A - Photographing device provided with trimming photographing mechanism - Google Patents

Abstract

PURPOSE:To obtain an excellent image at any time both at the time of ordinary photographing and at the time of trimming photographing by relatively changing a space between two lens groups, a 1st lens group and a 2nd lens group, constituted of specified lenses out of a photographing optical system at the time of trimming photographing. CONSTITUTION:The photographing optical system 10 is constituted of three lenses such as the 1st lens group A consisting of two lenses, a positive lens 1 having positive refractive force and a negative lens 2 having negative refractive force, and the 2nd lens group B consisting of a single positive lens 3 having the positive refractive force in order from an object side. Then, it is provided with at least two modes such as a 1st mode in which photographing is performed by setting a 1st photographing range out of a photographing range photographed by the optical system 10 and a 2nd mode in which photographing is performed by setting a 2nd photographing range which is smaller than the 1st range. In the case of mutually switching the 1st and the 2nd modes, the space between the 1st and the 2nd lens groups A and B is relatively changed. Thus, the excellent image is obtained at any time both at the time of ordinary photographing and at the time of trimming photographing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a photographing device having a trimming photographing mechanism.
In particular, by appropriately setting the lens configuration of the photographic optical system, it is possible to perform normal shooting (the first mode that targets the normal shooting range) and cropping shooting (targets the shooting range that is narrower than the shooting range of the first mode). In shooting with at least two modes (second mode), images with good image quality (
The present invention relates to a photographing device having a trimming photographing mechanism with a simple configuration that allows for easy acquisition of photographs (for example, photographs).

(Prior art) Traditionally, a switching mechanism has been used to switch between normal photography and cropping photography, and the current photography mode and cropped area can be recognized even from outside the camera or within the field of view of the viewfinder. For example, Japanese Patent Application Laid-Open No. 62-52541 proposes a photographing device having a trimming photographing mechanism for photographing the subject.

Further, Japanese Patent Application Laid-Open No. 54-26721 proposes a photographing device (camera) capable of writing so-called trimming information, which records image information indicating an enlargement range set at the time of photographing on the film.

Generally, aberrations are corrected in photographic lenses for photographic cameras, video cameras, etc. so that well-balanced optical performance can be obtained over the entire screen.

The tendency of aberration correction in ordinary photographic lenses is that the best image plane position, which indicates field curvature, falls toward the under-corrected (minus) side as you move from the center of the photographic range (optical axis) to the periphery of the screen.
Thereafter, it returns to the over-correction (plus) side and is designed to be located somewhat on the over-correction (plus) side at the very edge of the screen.

This results in a well-balanced image of good quality across the entire screen. When the entire screen is normally enlarged, a good image (photograph) can be obtained with almost no noticeable deterioration in image quality.

(Problem to be Solved by the Invention) An image taken using this type of photographic lens is cropped, and the image is taken in a narrower photographing range (trimming range) than the normal photographing range. Sometimes it is stretched and printed.

At this time, in the image within the trimming range, the best image plane position is largely tilted toward the negative side at the most peripheral part of the screen, so that the optical performance at the peripheral part of the screen is greatly degraded compared to the central part. For this reason, there is a problem in that the balance of the image quality of the entire trimmed screen is greatly disturbed.

That is, when an image is obtained by enlarging a trimming range in which aberration correction is insufficient for the entire screen, there is a problem in that the deterioration in image quality becomes significant and the resulting image (photograph) becomes very unsightly.

In order to solve the above-mentioned problems, the present invention appropriately sets the lens configuration of the photographic lens and adjusts the distance between the two lens groups that make up the photographic lens during trimming photography. Good images can be obtained both during cropping shooting and when shooting various shots in a narrower range than the shooting range during normal shooting (
The purpose of the present invention is to provide a photographing device having a trimming photographing mechanism capable of obtaining a photograph (photograph).

(Means for Solving the Problems) A photographing device having a trimming photographing mechanism according to the present invention has a first mode in which a first photographing range is set and photographed among the photographing ranges photographed by the photographing optical system; The photographing optical system has at least two modes, a second mode for setting and photographing a second photographing range that is smaller than the first photographing range, and the photographing optical system includes a first lens group and a second lens group in order from the object side. The second lens group has two lens groups, the first lens group has two lenses, a positive lens with positive refractive power and a negative lens with negative refractive power, and the second lens group has two lenses: a positive lens with positive refractive power and a negative lens with negative refractive power. It has two positive lenses,
The present invention is characterized in that when switching between the first mode and the second mode, the distance between the first lens group and the second lens group is relatively changed.

(Example) FIG. 1 is a lens sectional view of Numerical Example 1, which will be described later, of the photographing lens according to the present invention.

In the figure, lO is a photographing optical system (also referred to as a photographing lens).

), and includes a first lens group A consisting of two lenses, a positive lens 1 with a positive refractive power and a negative lens 2 with a negative refractive power, in order from the object side, and a single positive lens 3 with a positive refractive power. The second consisting of
It consists of a total of three lenses in lens group B. Reference numeral 4 denotes a diaphragm, which is arranged behind the second lens group B. 5
is a film and is placed on the image plane.

FIG. 2 is a diagram showing various aberrations of the photographing lens shown in FIG. 1 during normal photographing (first mode).

In this embodiment, the aberration correction of the photographing lens IO during normal shooting is performed over the entire effective screen of the film 5 disposed on the image forming plane (II shadow angle of view 2ω = 62°) as shown in the aberration diagram of FIG.
) has been corrected in a well-balanced manner.

As a result, a well-balanced and good image (photograph) can be obtained over the entire effective area of the film 5 during normal photographing.

Next, a second mode that targets a shooting range a narrower than the first mode, that is, a trimming range a as shown in FIG.
When photographing by specifying the photographing angle of view 2ω=33.4°, it is assumed that the aberration correction state shown in FIG. 2 is switched to cropping photographing.

At this time, the most peripheral part of the screen in the trimming range a (ω=16.
As shown in FIG. 2, the field curvature at 7°) is the most under-corrected (corresponding to being located at the most prominent part of the aberration curve).

For this reason, if the narrow trimming range a is enlarged to the same size as the normal photographing range and printed using automatic development and printing, the resulting image (photograph) will be of extremely degraded image quality. Therefore, in this embodiment, (a) In general, when shooting with trimming, the target shooting angle of view is different from when shooting with normal shooting, and there is no need to consider aberration correction for the entire angle of view, and the angle of view is limited to only within the trimming range. That's something you should consider.

(b) Furthermore, within this trimming photography range, it is desirable to perform aberration correction even better than during normal photography, considering the enlargement magnification.

Considering the above points, when performing trimming photography, by relatively changing the distance between the first lens group A and the second lens group B that constitute the photographing optical system 10, for example, by widening the distance between the first lens group A and the second lens group B. (In this example, the distance between the first and second lens groups A and B is changed by 2 as shown in Numerical Example 1 (described later) before (during normal shooting) and after (during trimming shooting). .02 to 2.52 and 0.5
(the lens is widened by a wide range of angles), so that aberration correction is performed in the most balanced manner within the cropping shooting range. As a result, images (photographs) of good quality are obtained within the cropped shooting range.

FIG. 3 is an aberration diagram showing a state in which various aberrations are corrected within the trimming photographing range at the time of cropping photographing at this time.

As shown in the same figure, at the same angle of view at the most peripheral part of the screen (half angle of view ω = 31°) as in normal shooting shown in Fig. 2,
The field curvature (the average value of the meridional image surface M and the sagittal image surface S) is largely overcorrected. In this state, for example, it is assumed that the photographing screen is trimmed to half (area ratio 1/4) and the photographing angle of view is set to ω=16.7°. Then, the most peripheral part of the screen (ω=
16.7°) field curvature during normal shooting (half angle of view ω
= 31°). Furthermore, even if each aberration of distortion and chromatic aberration of magnification is corrected, it becomes better as shown in the figure, compared to the case where the distance between the lens groups is not adjusted.

Of these, lateral chromatic aberration, in particular, is exaggerated by cropping, just like field curvature, but the aberrations within the cropping range are better corrected compared to the range during normal shooting, so it works well even when the screen is enlarged. You can get the image quality.

In this embodiment, in order to prevent the focus from shifting when the distance between the first lens group A and the second lens group B is changed, the light flux emitted from the first lens group A is made to be approximately an afocal light flux. It is desirable to configure the photographic optical system to

In addition, in this embodiment, in order to obtain a good quality image during cropping photography, the focal length of the first lens group A is |f1,
It is preferable to satisfy the following condition: l|f1/fAl≧2 (+), where fA is the focal length of the photographing optical system during normal photographing.

Conditional expression (1) relates to the ratio of the focal length of the first lens group A to the focal length of the photographing optical system during normal shooting. When cropping photography is performed by increasing the distance between the lens groups, fluctuations in spherical aberration increase, and the amount of change in back focus also increases, which is not good.

In addition, in this embodiment, if the amount of change in back focus is sufficiently small, it is possible to move only the first lens group A with respect to the film plane (imaging plane) and change the lens group spacing during trimming photography. Various aberrations can be corrected in a well-balanced manner within the cropping shooting range. According to this, it is possible to greatly simplify the mechanism.

In this way, in this embodiment, as described above, the photographing optical system is composed of three lenses as a whole, and the distance between the first lens group A and the second lens group B is relatively changed during trimming photographing. By doing so, the most preferable aberrations are corrected within the cropping photography range, and thereby a pseudo-telephoto effect by cropping photography can be obtained with good performance at an extremely low cost.

Next, the control when performing trimming photography according to this embodiment will be explained using the block diagram shown in FIG. 4.

In the figure, reference numeral 41 denotes a trimming range setting member that allows the photographer to set and operate a plurality of trimming shooting ranges, and in conjunction with the operation of this setting member 41, the trimming shooting range in the finder formed by, for example, a liquid crystal display changes. .

The determined trimming photographing range is converted into an electrical signal and the information is stored in the storage device 42. Then, the trimming information recording device 43 imprints on the film 5 using optical means based on the information stored in the storage device 42 based on a predetermined standard.

Furthermore, before photographing, the control circuit 44 corrects aberrations within the trimming photographing range based on information regarding the trimming photographing range stored in the storage device 42. That is, the first lens group A is moved in a direction in which the distance between the lens groups A and H becomes wider, as indicated by the arrow shown in the figure. In this way, control is performed when cropping photography is performed.

Note that it is of course possible to move the first lens group A in conjunction with the trimming range setting member 41.

Also, in the figure, when performing cropping photography, the case is shown in which only the first lens group A is moved to correct aberrations within the trimming range, but of course only the second lens group B or the first lens group A and the first lens group A are moved. It is also possible to move the two lens groups B together and change the distance between the lens groups, for example, by changing it in the direction of increasing it.

Note that the aperture 4 is the first lens group A or the second lens group B.
It may be moved integrally with any of the lens groups,
Alternatively, they may be configured independently. Furthermore, as for the aperture, either a medium aperture type placed between both lens groups A and B, or a rear aperture type placed behind the second lens group B as shown in the first embodiment may be adopted. good.

Fifth. FIG. 8 is a cross-sectional view of numerical examples 2 and 3 of the photographing lens according to the present invention, which will be described later.

6th. Figure 9 shows numerical example 2 of the photographing lens of the present invention.
．． Figures 3 and 7 are diagrams showing various aberrations during normal photographing, and Figures 7 and 10 are diagrams showing various aberrations during trimming photographing according to Numerical Example 2.3 of the photographing lens of the present invention.

Regardless of which embodiment is used, in the same way as in the first embodiment described above, during trimming photography, by changing the distance between the first lens group A and the second lens group B in the direction of relatively widening. , for example, various aberrations such as field curvature are corrected in a well-balanced manner within the trimming range, thereby making it possible to obtain a pseudo-telephoto effect with good performance through trimming photography.

In each example, two modes are shown: normal shooting (first mode) and trimming shooting (second mode), but the imaging range (shooting range) is further improved in the second mode. Small example 3rd. You may also specify trimming photography by switching to a fourth plurality of modes.

Furthermore, although the above embodiments have shown examples using a single lens, the photographing optical system may also be configured with a zoom lens. In this case as well, when performing trimming photographing as in the above embodiments, for example, a relay lens system may be used. The first lens group A and the second lens group B of
If the distance between the lens groups and the lens group is changed appropriately, good cropping photography can be achieved in the same way as described above.

Next, numerical examples of the present invention will be shown. In numerical examples R
i is the radius of curvature of the i-th lens surface in order from the object side, D
i is the i-th lens thickness and air distance from the object side, Ni
and vi are the refractive index and Abbe number of the glass of the i-th lens, respectively, in order from the object side.

Numerical Example 1 f-36,0 RI-10,29 R2-33,90 R3--69,01 R4~ 9.54 R5-56,47 86@-26,85 87・When shooting with aperture trimming f-35 ,88 2ω・33.49 |f1/f^ Numerical Example 2 f-34,O R+-10,78 82-33,60 R3--55,86 R4-10,32 R5-47,12 R6 E- 25,77 87-Aperture-3,79 FNO-1:3.7 2ω-62@ b-f-27
,28D I-3,60N +-1,78650ν
l-50, OD 2- 0.80 D 3- 0.80 D 4・2.02 D 5- 1.21 D 6- 1.21 N 3=1.80610 v 3-40.9N
2”1.68893 v 2-31.1D4 −
2.52 FNO-1:3.7 b-f-27,25 FNO-1:3.5 2ω-65,2” b-f
-25,81D I-3,59N I-1,786
50v l-50, OD 2- 0.87 D 3- 1.01 D 4- 1.95 D 5- 1.79 D 6- 1.21 N 3-1.80810 ν 3-40.9N
2-1.68893 ν 2-31.1 When shooting with trimming f -33,75 2ω-35,4" D4 -2.45 FNO-1: 3.5 b-f-25,77 | f1/fAl-3 ,22 Numerical Example 3 f-34,0 RI-10,08 R2-30,77 R3--85,57 84-9,53 85-44,30 86--24,49 87-When shooting with aperture trimming f -33,9゜2ω -35,4゜FNO-1:3.5 2ω-65,2° b-f-2
5,77D I-3,11N +-1,84+00v
l-43,2D 2- 0.85 D 3- 0.80 D 4- 2.18 D 5- 1.60 D 6- 1.2O N 2-1.72825 ν 2-28.5N 3-
1.72000 v 3 = 43.7D4 -2.4
0 FNO-1: 3.5 b-f-25,76 (Effect of the invention) According to the present invention, in the photographing optical system, two lens groups, the first lens group and the second lens group, each consisting of a predetermined lens. By relatively changing the distance between the lens groups during cropping photography, various aberrations such as field curvature within the cropping photography range can be corrected in a well-balanced manner, and images with good image quality can be obtained over the entire screen. It is possible to achieve a photographing device having a trimming photographing mechanism capable of performing cropping photographing according to the present invention.

[Brief explanation of drawings]

1st. Fifth. FIG. 8 is a lens sectional view of Numerical Examples 1 and 2.3 of the photographing lens according to the present invention, and 2. 6th. 9th
The figures show numerical examples 1 and 2 of photographic lenses according to the present invention, respectively.
3. Diagrams of various aberrations during normal photography, 3rd. 7th. FIG. 10 is a diagram showing various aberrations during trimming photography in Numerical Examples 1, 2, and 3 of the photographic lens according to the present invention, and FIG. 4 is a block diagram when performing trimming photography according to the present invention. In the figure, A is the first lens group, B is the second lens group, 0 is the photographing optical system, 3 is a positive lens, 2 is a negative lens, 4 is an aperture, and 5 is a film.

Claims (2)

[Claims] (1) The first part of the photographing range photographed by the photographing optical system
It has at least two modes: a first mode in which a photographing range is set and photographed, and a second mode in which a second photographing range which is smaller than the first photographing range is set and photographed; The photographing optical system has two lens groups, a first lens group and a second lens group, in order from the object side, and the first lens group has two lenses: a positive lens with positive refractive power and a negative lens with negative refractive power. The second lens group has one positive lens, and when switching between the first mode and the second mode, the first lens group A photographing device having a trimming photographing mechanism characterized in that the distance between the lens groups of the second lens group is relatively changed. (2) When the focal lengths of the first lens group and the photographing optical system in the first mode are respectively f1 and fA, the following condition is satisfied: |f1/fA|≧2 A photographing device comprising the trimming photographing mechanism according to claim 1.