JP2780460B2 - Imaging device having trimming imaging mechanism - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing apparatus having a trimming photographing mechanism, and more particularly, to a normal photographing (targeting a normal photographing range by appropriately setting a lens configuration of a photographing optical system). (1st mode) and trimming shooting (second mode for a shooting range narrower than the shooting range of the first mode) in images having at least two modes. And the like, and a photographing apparatus having a trimming photographing mechanism with a simple configuration that can easily be obtained.

(Prior Art) Conventionally, one of a normal photographing mode and a trimming photographing mode is switched by a switching mechanism, and the photographing mode and the range to be trimmed at this time are recognized both from outside the camera and within the viewfinder field of view. A photographing apparatus having a trimming photographing mechanism for photographing has been proposed in, for example, JP-A-62-52541.

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

In general, a photographing lens such as a photographic camera and a video camera is aberration-corrected so as to obtain a well-balanced optical performance over the entire screen.

As a tendency of aberration correction in a normal photographing lens, the best image plane position showing the curvature of field falls in the direction of undercorrection (minus) from the center (optical axis) of the photographing range toward the periphery of the screen, and then overcorrection ( It is designed so that it returns to the (plus) side and is located on the slightly overcorrected (plus) side at the periphery of the screen.

As a result, an image of good image quality that is balanced over the entire screen is obtained. Then, when a normal entire screen is stretched, a good image (photograph) with almost no concern about deterioration in image quality is obtained.

(Problems to be Solved by the Invention) Trimming is performed on an image photographed using this kind of photographing lens, and an image in a photographing range (trimming range) narrower than a normal photographing range is targeted. May be stretched and burned.

At this time, among the images in the trimming range, the best image plane position is greatly inclined to the minus side in the most peripheral part of the screen,
The optical performance at the peripheral portion of the screen is greatly reduced as compared with the central portion. For this reason, there is a problem that the balance of the image quality of the entire trimming screen is greatly lost.

That is, when an image is obtained by extending a trimming range in which the aberration correction is insufficiently corrected over the entire screen, the image quality is significantly deteriorated, resulting in a very unsightly image (photograph).

The present invention solves the above-mentioned problems by appropriately setting the lens configuration of the photographing lens and adjusting the lens group interval between the two lens groups constituting the photographing lens during trimming photographing, thereby improving the normal photographing time. It is another object of the present invention to provide a photographing apparatus having a trimming photographing mechanism capable of obtaining a good image (photograph) at any time of trimming photographing when variously photographing a range narrower than a photographing range at the time of normal photographing. .

(Means for Solving the Problems) A photographing apparatus having a trimming photographing mechanism according to the present invention includes: a first mode in which a first photographing range is set and photographed among photographing ranges photographed by a photographing optical system; And at least two modes of a second mode for setting and photographing a second photographing range smaller than the first photographing range,
The photographing optical system includes two lens groups of a first lens group and a second lens group in this order from the object side. The first lens group includes a positive lens having a positive refractive power and a negative lens having a negative refractive power.
The second lens group comprises one positive lens, and when switching between the first mode and the second mode, the first lens group and the second lens When the distance between the lens groups of the groups is relatively changed, and the focal lengths of the first lens group and the photographing optical system in the first mode are f1 and fA, respectively, | f1 / fA | ≧ 2 (1) The following condition is satisfied.

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

In FIG. 1, reference numeral 10 denotes a photographing optical system (also referred to as a photographing lens), which is a positive lens 1 having a positive refractive power in order from the object side.
And a negative lens 2 having a negative refractive power.
It comprises a total of three lenses, a lens group A and a second lens group B comprising a single positive lens 3 having a positive refractive power.
Reference numeral 4 denotes a stop, which is arranged behind the second lens group B. Reference numeral 5 denotes a film, which is arranged on the image forming surface.

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

In this embodiment, the aberration correction of the photographing lens 10 during normal photographing is balanced over the entire effective screen (filming angle of view 2ω = 62 °) of the film 5 arranged on the image plane as shown in the aberration diagram of FIG. It is well corrected.

As a result, a good image (photograph) that is well-balanced over the entire effective screen area of the film 5 during normal shooting is obtained.

Next, in the second mode, which targets a shooting range a narrower than the first mode, that is, when shooting is performed by specifying a trimming range a (shooting view angle 2ω = 33.4 °) as shown in FIG.
It is assumed that switching to the trimming shooting is performed in the state of the aberration correction shown in FIG.

At this time, the outermost peripheral portion of the screen in the trimming range a (ω = 16.7
As shown in FIG. 2, the field curvature in ゜) is in the state of the least correction (corresponding to the position that is located at the most protruding part of the aberration curve).

For this reason, if the narrow trimming range a is stretched to the same size as the normal photographing range and printed by automatic developing and printing, an image (photograph) with extremely deteriorated image quality results. Therefore, in this embodiment, (a) in general, the target shooting angle of view is different from that of normal shooting during trimming shooting, and it is not necessary to consider aberration correction over the entire angle of view. Things to consider.

(B) Further, in consideration of the enlargement magnification within this trimming photographing range, it is desirable to perform aberration correction better than at the time of normal photographing.

In consideration of the above points, when performing trimming photographing, the distance between the first lens group A and the second lens group B constituting the photographing optical system 10 is relatively changed, for example, by widening. (In this embodiment, before changing the distance between the first and second lens groups A and B (during normal shooting)
And Numerical Example 1 to be described later (at the time of trimming shooting)
The interval is increased from 2.02 to 2.52 and 0.5 as shown in (2)), so that aberration correction is performed in the best balance within the trimming shooting range. As a result, an image (photograph) of good image quality is obtained within the trimming photographing range.

FIG. 3 is an aberration diagram showing a state in which various aberrations are corrected for the inside of the trimming shooting range at the time of trimming shooting at this time.

As shown in FIG. 2, at the same angle of view (half angle of view ω = 31 °) at the outermost periphery of the screen as in the normal shooting shown in FIG.
The field curvature (the average value of the meridional image plane M and the sagittal image plane 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 view angle is set to ω = 16.7 °. Then, the outermost part of the screen at the time of trimming shooting (ω = 16.7
The field curvature of ゜) is for normal shooting (half angle of view ω = 31 °)
Better than. Also, each of the distortion and the chromatic aberration of magnification is better as shown in FIG.

Among them, especially the chromatic aberration of magnification is exaggerated by the same way as the curvature of field due to the dreaming, but since the aberration is better corrected in the trimming range as compared with the range at the time of normal shooting, it is good even when the screen is greatly extended. Image quality is obtained.

In the present embodiment, in order to prevent a focus movement when the distance between the first lens unit A and the second lens unit B is changed, the light beam emitted from the first lens unit A is substantially an afocal light beam. It is desirable to configure a photographing optical system.

Further, in this embodiment, in order to obtain an image of good image quality during trimming photographing, when the focal length f1 of the first lens unit A and the focal length of the photographing optical system during normal photographing are fA | f1 / fA | ≧ 2 It is preferable to satisfy the following condition.

Conditional expression (1) relates to the ratio of the focal length of the first lens unit A to the focal length of the photographing optical system during normal photographing. When trimming photographing is performed by enlarging the lens group interval, the fluctuation of spherical aberration increases, and the amount of change in back focus also increases, which is not good.

In the present embodiment, if the amount of change in the back focus is sufficiently small, it is possible to move only the first lens unit A with respect to the film surface (imaging surface) and change the lens unit interval during trimming photographing. Various aberrations can be corrected with good balance within the trimming photographing range. According to this, the mechanism can be greatly simplified.

Thus, in the present embodiment, as described above, 3
The photographing optical system is composed of two lenses, and during trimming photographing, the most preferable aberration correction is performed within the trimming photographing range by relatively changing the lens group interval between the first lens group A and the second lens group B. This makes it possible to obtain a pseudo-telephoto effect by trimming photography at an extremely low cost with good performance.

Next, control for performing trimming photographing in this embodiment will be described with reference to the block diagram of FIG.

In the figure, reference numeral 41 denotes a trimming range setting member which allows a photographer to set and operate a plurality of trimming shooting ranges. The trimming shooting range in a finder formed of, for example, a liquid crystal or the like changes in accordance with the operation of the setting member 41. .

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

Further, before photographing, the control circuit 44 performs aberration correction in the trimming photographing range based on the information on the trimming photographing range stored in the storage device 42. That is, the first lens unit A is moved in the direction in which the distance between the two lens units A and B increases as indicated by the arrow shown in FIG. In this way, control for performing trimming photographing is performed.

The first lens group A can be moved in conjunction with the trimming range setting member 41.

In addition, FIG. 3 shows a case where only the first lens group A is moved as an aberration correction within the trimming range when performing the trimming photographing.
Alternatively, the first lens group A and the second lens group B may be moved together to change the distance between the lens groups, for example, to increase the distance.

The diaphragm 4 may be moved integrally with any one of the first lens group A and the second lens group B, or may be independently formed. As the diaphragm, either a middle diaphragm type disposed between the two lens units A and B, or a diaphragm type disposed behind the second lens group B as shown in the first embodiment may be employed. .

FIGS. 5 and 8 are lens sectional views of Numerical Examples 2 and 3 of the taking lens according to the present invention, which will be described later.

FIGS. 6 and 9 show numerical examples 2,
FIG. 3 shows various aberration diagrams at the time of normal photographing, and FIGS. 7 and 10 are various aberration diagrams at the time of trimming photographing according to Numerical Examples 2 and 3 of the photographing lens of the present invention.

In any of the embodiments, the trimming is performed by changing the distance between the first lens group A and the second lens group B in the direction of relatively widening at the time of trimming photographing as in the first embodiment. Within the range, for example, various aberrations such as curvature of field are corrected in a well-balanced manner, whereby a pseudo-telephoto effect by trimming photographing can be obtained with good performance.

In each embodiment, during normal shooting (first mode)
And the two modes of trimming shooting (second mode) have been described. However, the image forming range (shooting range) is smaller than that of the second mode. May be specified.

In the above embodiment, an example of a single lens is shown. However, the photographing optical system may be constituted by a zoom lens. In this case, when trimming photographing is performed in the same manner as in the above-described embodiment, for example, a relay lens system may be used. If the distance between the first lens group A and the second lens group B is relatively appropriately changed, favorable trimming photography can be performed as described above.

Next, numerical examples of the present invention will be described. In numerical examples
Ri is the radius of curvature of the i-th lens surface in order from the object side,
Is the i-th lens thickness and air gap from the object side, Ni and ν
i is the refractive index and Abbe number of the glass of the i-th lens in order from the object side.

(Effects of the Invention) According to the present invention, in the photographing optical system, the distance between the two lens groups of the first lens group and the second lens group, each of which includes a predetermined lens, is relatively changed during trimming photographing. A photographing apparatus having a trimming photographing mechanism capable of performing a trimming photographing in which the various aberrations within the trimming photographing range, for example, various aberrations such as curvature of field, are corrected in a well-balanced manner and an image of good image quality is obtained over the entire screen. Can be achieved.

[Brief description of the drawings]

FIGS. 1, 5 and 8 are sectional views of numerical examples 1, 2, and 3 of the photographing lens according to the present invention, respectively. FIGS. 2, 6, and 9 are numerical values of the photographing lens according to the present invention, respectively. Various aberration diagrams of Examples 1, 2, and 3 during normal photographing, and FIGS. 3, 7, and 10 are various aberration diagrams during trimming photographing of Numerical Examples 1, 2, and 3 of the photographing lens according to the present invention, respectively. ,
FIG. 4 is a block diagram when performing trimming photographing according to the present invention. In the figure, A is the first lens group, B is the second lens group, 10 is a photographing optical system, 1, 3 is a positive lens, 2 is a negative lens, 4 is an aperture,
Is a film.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03B 17/12 G02B 15/15

Claims (1)

(57) [Claims] 1. A first mode for setting and photographing a first photographing range among photographing ranges photographed by a photographing optical system and a second photographing range smaller than the first photographing range. The imaging optical system includes at least two modes of a first lens group and a second lens group in order from the object side, and the first lens group Is composed of two lenses, a positive lens having a positive refractive power and a negative lens having a negative refractive power. The second lens group is composed of one positive lens, and the first mode and the second mode are mutually reciprocal. When switching between the first lens group and the second lens group, the distance between the lens groups is relatively changed, and the first lens group and the photographing optical system in the first mode are changed. | F1 / fA | ≧ 2 when the focal lengths of the lenses are f1 and fA, respectively. Imaging device having a trimming photographing mechanism to symptoms.