JP2001013301A - Photographing lens, photographic filter and film unit with lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent overexposure from occurring by automatically reducing light transmitted through a photographing lens and to widen an exposure range by specifying the variance of the transmissivity of the light through three wavelength ranges having specified sensitivity with respect to peak sensitivity. SOLUTION: This photographing lens is constituted by including photochromic material. On a condition that the transmissivity of the light is reduced by the photochromic material, the variance of the transmissivity of the light is set to be <=20% through three wavelength ranges having the sensitivity being >=80% of the peak sensitivity as for three respective primary colors of a color image recording medium to be used. In the figure of a light absorbing characteristic, a continuous line is the graph of the transmissivity in the case of high luminance being >=13 EV that the light is absorbed. The wavelength range through which the transmissivity becomes >=40% exists but the transmissivity of the light becomes <=40% and >=20% through the three wavelength ranges having the sensitivity being >=80% of the peak sensitivity at least as for the three respective primary colors (Y, M and C) of a color negative film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photographic lens containing a photochromic material, a photographic filter, and a film unit with a lens provided with the photographic lens or the photographic filter.

[0002]

2. Description of the Related Art A lens-equipped film unit does not have an exposure control mechanism, unlike a general camera, so that it can be provided at a low cost. The photographing is performed with the exposure amount determined in.

For example, assuming that a film of ISO 400 is built in, the shutter speed is 1/100, and the aperture is F10, the EV value converted to ISO 100 is 11.3 EV. In the following description, EV values are based on ISO 100 unless otherwise noted.

[0004] When shooting at 11.3 EV, a high-brightness ski resort or seashore has about 15 EV.
Although overexposure at the EV level occurs, the overexposure of the color film built in the film unit with a lens can be corrected by the latitude of the film.
On the other hand, when photographing in the early morning or evening when the brightness is low, underexposure may occur, but underexposure of about 2EV is a limit that can be corrected by the latitude of the film. Therefore, flash photography may be performed at a short distance, no matter how low the brightness. However, it is difficult to photograph a long-distance scenery or the like in the early morning or evening in a conventional film unit with a lens.

[0005]

In order to use a film unit with a lens to shoot a landscape at a long distance in the early morning or the evening, a film with a higher sensitivity, for example, a film of ISO800 is to be incorporated. There is. In this case, assuming the same shutter speed and aperture as described above.
3 EV, which enables shooting of low-brightness scenery and the like.
In the case of photographing the subject, the photograph exceeds the correction limit of the latitude of the film, resulting in an overexposed photograph. Also,
Therefore, if the shutter speed is increased or the aperture is reduced, the low-luminance shooting limit shifts to the high-luminance side, and it becomes unclear why the ISO800 film is incorporated.

It is also conceivable to use a brighter photographing lens in order to be able to photograph a landscape at a long distance in the early morning or evening. For example, assuming that a photographic lens having an aperture of F5.6 is used, an ISO400 film is built in, and the shutter speed is set to 1/100, the EV value converted to ISO100 is 9.6EV. Therefore, a low-brightness landscape or the like can be photographed, but a high-brightness subject is extremely overexposed.

As described above, it is difficult to shoot a high-brightness subject or a low-brightness subject using a film unit with a lens that does not perform exposure control at all.

For this purpose, a higher sensitivity film or a brighter photographing lens is used to set a lower exposure amount as a photographing reference. In the case of high luminance, an ND filter is provided in front of the photographing lens. It is conceivable to wear it,
A general user does not want to be troublesome and cannot judge at what brightness the ND filter should be mounted.

The present invention has been made in view of such a problem, and sets a reference exposure amount to a low brightness, and automatically reduces the light transmitted through the photographing lens when the brightness is high, thereby causing an overexposure. It is an object of the present invention to provide a photographic lens, a photographic filter, and a lens-equipped film unit that can prevent the occurrence of a problem with a simple configuration and can expand an exposure range.

[0010]

The above object can be attained by any of the following means.

[0011] A photographing lens containing a photochromic material, wherein the color image recording medium to be used in a state where light transmittance is reduced by the photochromic material.
A photographic lens, wherein for each of the primary colors, a variation in light transmittance is 20% or less through three wavelength ranges having a sensitivity of 80% or more with respect to a peak sensitivity.

A photographic filter containing a photochromic material, wherein, in a state where the light transmittance is reduced by the photochromic material, each of the three primary colors of the color image recording medium to be used is 80% of the peak sensitivity.
A photographic filter, wherein the variation in light transmittance is 20% or less throughout the three wavelength ranges having the above sensitivity.

A film unit with a photographing lens or a photographic filter containing a photochromic material, wherein each of the three primary colors of a color image recording medium to be used in a state where light transmittance is reduced by the photochromic material. 80 for peak sensitivity
A lens-equipped film unit comprising: a photographing lens or a photographic filter having a light transmittance variation of not more than 20% over three wavelength ranges having a sensitivity of not less than 20%.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

In the film unit with a lens according to the present embodiment, as shown in FIG. 1, the photographing lens has one or at most two lenses, and is formed by molding an acrylic resin containing a photochromic material. By including a photochromic material in the acrylic resin, the transmitted light amount of the photographing lens is changed in accordance with the change in luminance.

The photochromic material is a material exhibiting a reversible change in which when light is irradiated, the light is absorbed and the transmittance is reduced, and when the irradiation is stopped, the light is not absorbed and returns to the original transmittance. If a photographic lens is molded by incorporating such a photochromic material into an acrylic resin and the EV value serving as a photographic reference is set to a low value, the image is photographed in a state where the photochromic transmittance does not decrease at a low luminance, resulting in insufficient exposure. In high brightness, shooting is performed with reduced transmittance, so that overexposure does not occur. Therefore, without providing a complicated and expensive exposure control mechanism as used in a camera, a lens-equipped film unit capable of automatically changing the amount of transmitted light of a photographing lens in response to a change in luminance is realized. be able to. In addition, a photographic filter containing a photochromic material may be always mounted in front of the photographic lens, instead of the photographic lens.

One example of such a photochromic material is shown in the light absorption characteristic diagram of FIG. This photochromic material is used for sunglasses, and the horizontal axis in the figure is wavelength and the vertical axis is transmittance. The upper broken line graph shows the transmittance in the case of low brightness, and the lower solid line graph shows the transmittance in the case of high brightness.

FIG. 3 is a graph showing the spectral sensitivity of an average color negative film. The horizontal axis in the figure is the wavelength, and the vertical axis is the specific sensitivity.

A comparison between FIG. 2 and FIG. 3 shows that the transmittance of the photochromic material does not decrease even when the luminance becomes high at the red color wavelength of cyan C. Therefore, when photographing is performed at a high luminance using a photographing lens or a photographic filter containing such a photochromic material, the color balance is poor and a reddish photograph results. For this reason, it is necessary to correct using a color filter at the time of printing,
Work efficiency is not good in this state.

Therefore, a photochromic material that absorbs light as shown in FIG. 4 was used. In the light absorption characteristic diagram of FIG. 4, the solid line is a graph of the transmittance at a high luminance of 13 EV or more at which light is absorbed. Some wavelengths have a transmittance of 40% or more, but at least three primary colors of the color negative film. The light transmittance is 40% or less and 20% or more through three wavelength ranges having a sensitivity of 80% or more of the peak sensitivity for each of (Y, M, and C in FIG. 3). That is, the variation of the transmittance is within 20% throughout the three wavelength ranges.

Here, the variation in transmittance of 20% or less throughout the three wavelength ranges means that the wavelength range of the peak sensitivity for Y is 80% or more, the wavelength range of the peak sensitivity for M is 80% or more, C Peak sensitivity is 80
%, The difference between the minimum transmittance and the maximum transmittance is 20% or less in the three wavelength ranges.

The wavelength range having a sensitivity of 80% or more of the peak sensitivity will be specifically described with reference to FIG. 3. For example, in the case of Y in FIG.
Since it is 65, the sensitivity of 80% of the peak sensitivity is 1.55 in logarithm of the specific sensitivity, and the sensitivity of 50% of the peak sensitivity is 1.35 in logarithm of the specific sensitivity. Therefore, the sensitivity range of 80% or more of the peak sensitivity is about 430 nm to 480 nm, and the sensitivity range of 50% or more of the peak sensitivity is about 410 nm to 490 nm.
Range.

Note that the broken line is a graph in the case of low brightness of 8 EV or less without light absorption.

Therefore, when a photographing lens or a filter is formed by incorporating such a photochromic material into an acrylic resin and photographing is performed, the amount of transmitted light with respect to the main wavelength of the photographing lens changes uniformly in accordance with the external luminance. The photo will not be out of balance.

Further, when a photochromic material that absorbs light is used as shown in the light absorption characteristic diagram of FIG. 5, a photograph having better color balance can be obtained. In FIG. 5, the solid line is a graph of the transmittance in the case of high luminance of 13 EV or more at which light absorption is performed, and the transmittance is 40% over the entire visible light wavelength range.
Hereinafter, it is 20% or more.

As described above, as a photochromic material, 1
At a high luminance of 3 EV or more, a film having a transmittance of 40% or less and 20% or more over three wavelength ranges having a sensitivity of 80% or more, preferably 50% or more of the peak sensitivity for each of the three primary colors of the color film is used. As a result, a photograph with good color balance can be obtained.

As a photochromic material, 8 EV
At the following low luminance, it is desirable that the transmittance be 80% or more through the above three wavelength ranges.

The broken lines in FIGS. 4 and 5 are graphs in the case of a low luminance of 8 EV or less without light absorption.

Here, in FIGS. 4 and 5, the difference in transmittance between low luminance and high luminance is about 1.5 EV. Therefore, for example, a photographing lens having a built-in ISO400 film, an open F number of F5.6, and a shutter speed of 1/1
Assuming that the value is 00, the reference EV value is 9.6 EV.
On the other hand, if the transmittance of the photographing lens is reduced by 1.5 EV at a high luminance of about 15 EV such as a ski resort or a beach, the photographing is substantially performed at 11.1 EV.
An overexposure of about 4 EV to 5 EV is a range that can be corrected by the latitude of the film. Therefore, if it is assumed that there is no problem on the high luminance side and that the low luminance side can be corrected by -2 EV with the latitude of the film, it is possible to photograph up to a low luminance of 7.6 EV, so that morning and evening scenery can be sufficiently photographed. .

Note that, for example, the transmittance of the photographing lens does not rapidly change by 1.5 EV between 15 EV and 9.6 EV, but gradually changes between them, so that overexposure does not occur even at a luminance of 15 EV or less. .

Although a color negative film has been described above as an example of a recording medium for recording a color image, a color positive film may be used, or a CCD may be used as a recording medium in a digital camera.

[0032]

According to the photographic lens according to the first to third aspects, the photographic filter according to the fourth to sixth aspects, and the film unit with a lens according to the seventh to ninth aspects, the reference exposure amount can be reduced. Since the brightness is set low and the light transmitted through the photographing lens is automatically reduced in the case of high brightness to prevent overexposure, the exposure range can be made wider than before with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a diagram of a taking lens.

FIG. 2 is a light absorption characteristic diagram of a photochromic material.

FIG. 3 is a graph of spectral sensitivity of an average color negative film.

FIG. 4 is a light absorption characteristic diagram of a photochromic material.

FIG. 5 is a graph showing light absorption characteristics of a photochromic material.

Claims (9)

[Claims] 1. A photographic lens containing a photochromic material, wherein a color image recording medium to be used in a state where light transmittance is reduced by the photochromic material.
A photographic lens, wherein for each of the primary colors, a variation in light transmittance is 20% or less through three wavelength ranges having a sensitivity of 80% or more with respect to a peak sensitivity. 2. The method according to claim 1, wherein a variation in light transmittance of the three primary colors of the color image recording medium to be used is not more than 20% through three wavelength ranges having a sensitivity of not less than 50% with respect to the peak sensitivity. The photographing lens according to claim 1. 3. The imaging device according to claim 1, wherein when the brightness of the imaging environment is 13 EV or more, the light transmittance in the three wavelength ranges is 40% or less. lens. 4. A photographic filter containing a photochromic material, wherein each of three primary colors of a color image recording medium to be used is 80% of a peak sensitivity in a state where light transmittance is reduced by the photochromic material.
A photographic filter, wherein the variation in light transmittance is 20% or less throughout the three wavelength ranges having the above sensitivity. 5. The method according to claim 1, wherein a variation in light transmittance of the three primary colors of the color image recording medium to be used is not more than 20% through three wavelength ranges having a sensitivity of 50% or more with respect to the peak sensitivity. The photographic filter according to claim 4. 6. The photograph according to claim 4, wherein, when the brightness of the photographing environment is 13 EV or more, the light transmittance in the three wavelength ranges is 40% or less. Filter. 7. A film unit with a photographing lens or a lens provided with a photographic filter containing a photochromic material, wherein each of the three primary colors of a color image recording medium to be used in a state where light transmittance is reduced by the photochromic material. For the peak sensitivity
A lens-equipped film unit comprising: a photographing lens or a photographic filter having a light transmittance variation of not more than 20% over three wavelength ranges having a sensitivity of not less than 20%. 8. A photographing lens or a photograph in which, for each of the three primary colors of a color image recording medium to be used, a variation in light transmittance is 20% or less through three wavelength ranges having a sensitivity of 50% or more with respect to a peak sensitivity. The film unit with a lens according to claim 7, further comprising a filter for use. 9. A photographic lens or a photographic filter having a transmittance of light of 40% or less in the three wavelength ranges when the brightness of the photographic environment is 13 EV or more. A film unit with a lens according to claim 7 or claim 8.