JPS5950921B2 - Incident light exposure meter - Google Patents

Description

[Detailed description of the invention] The present invention relates to an incident light exposure meter.

It is well known that the types of exposure meters can be roughly divided into two types: incident light type and reflected light type.

The reflected light method measures the amount of light that is reflected by the surface of the object when it hits the object; therefore, the exposure meter is aimed at the object to measure the light. Both the TTL exposure meter built into single-lens reflex cameras and EE cameras can be said to be a type of reflected light exposure meter. This reflected light type exposure meter has the convenience of being able to measure light at the camera position because it measures light toward the subject itself, but on the other hand, the metering position is affected by the reflectance of the subject and the difference in lighting. There are some easy drawbacks. Here, regarding the measurement standard for the exposure meter, it is determined that the exposure meter measures light based on the case where the reflectance of the subject is 18%.

An object or color with a reflectance of 18 percent is generally considered to be a medium density clay.

The reflectance of 18%, which is the standard for light metering, is the average value of the reflectance of various subjects.If you take the average value of all things, such as black subjects and white subjects, the reflectance will be approximately 18%. That is what it is. Therefore, although the reflected light type exposure meter can accurately measure the light of a subject having an average reflectance of about 18%, it is susceptible to the influence of light from the subject and/or the background.

That is, in the case of a person wearing white clothes or glossy clothes with high reflectance, for example, the face of the person will be underexposed.
On the other hand, when a person wears black clothing with low reflectance, the person's face becomes overexposed. The same is true for TTL exposure meters. On the other hand, an incident light type exposure meter is of a type that directly measures the amount of light that hits the subject, and therefore measures the amount of light by placing the exposure meter at the position of the subject. In the case of this incident light type exposure meter, since it measures the amount (absolute amount) of the light rays incident on the subject, it has the advantage of being able to accurately measure light regardless of the subject's reflectance or lighting. However, it has the drawback that photometry is impossible unless it is right in front of the subject. The present invention has been made in view of the above-mentioned circumstances inherent in the prior art,
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel incident light type exposure meter that can measure light incident on a subject from close range to infinity at the photographing position using an incident light method. .

Another object of the present invention is to provide a novel light meter that combines the advantages of both the conventional incident light type and reflected light type.

, the present invention includes a first mirror that reflects a subject, a photoreceptor provided near the first mirror, a second mirror provided in front of the photoreceptor, and a first mirror and a second mirror provided in front of the photoreceptor. a lens group located between the mirrors and associated with pit alignment; and a lens group that cooperates with the lens group to place the second mirror in front of the image of the two objects reflected in the first mirror. a third mirror that projects light and guides the light incident on the subject image to the photoreceptor; the subject itself is captured by the first mirror, and the subject imaged in the first mirror; This is an incident light type exposure meter characterized in that the light incident on the image is guided to the photoreceptor by the lens group and the third two mirrors for photometry.
The principle of the present invention is that although a mirror is a flat surface, the image reflected on the mirror has a depth ranging from close range to infinity.
It is a three-dimensional world with axial coordinates, and all real three-dimensional events unfolding in front of the mirror are reproduced in exactly the same three-dimensional way inside the flat mirror. That is what we are doing.

For example, if you take a picture of a subject at a distance of A (m) from the front of the mirror and match it with 5 pits from the subject's position, the pits will match at a distance of 2A (m), and from this fact, the mirror is understood to have three-dimensional properties. The above properties of mirrors were obtained through many years of research by the inventor.
This was discovered as a result of experiments. Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a principle diagram according to an embodiment of the present invention.

In the figure, reference number M1 is the first mirror that reflects the subject S;
M2 is a third mirror (the second mirror will be described later), which is composed of a reflecting mirror with a suitable concave surface or a half mirror of the same shape (enlarges so that the projected image M3'' shown below does not become small during long-distance photometry). ), L is a projection lens group linked to pit alignment,
M3 is the front surface of the subject image S'' projected onto the first mirror M1 of the subject S by the projection lens group L (5 to 10 cm at close distance).
m, 2 to 50 m for medium and long distances), a second mirror with a through hole approximately in the center, D is a photoreceptor that receives the light, A is an amplifier, Q is a meter or e.g. The mechanism linked to the aperture or shutter speed of the camera is shown, respectively.
Here, if it is assumed that light from a light source P is incident on the subject S on the front surface of the first mirror M1 as shown in FIG. 1, a similar three-dimensional state will be reproduced in the first mirror M1. Therefore, the object S from the first mirror M1 is centered around the first mirror M1.
There is a subject image S'' reflected on the first mirror M1 at a position spaced backward from the first mirror M1 by a distance z, which is equal to the distance to It can be expressed as light coming from P''.

Therefore, if a mirror is placed in front of the subject image S'' to receive the light from the light source P'' and guide it to the photoreceptor, it will be equivalent to receiving the light incident on the subject S from the light source P in front of the subject S. That is understood. In the present invention, a second mirror M3 placed in front of the photoreceptor D in front of the subject image S'' is connected to the lens group L.
The third mirror M2 is used to project the light onto the first mirror M1 as M3'', and the light incident on the subject image S'' is transmitted to the photoreceptor D via the projection mirror M3'', the third mirror M2, and the lens group L. It is designed to lead to.

Therefore, the third mirror M2, the second mirror M3, and the lens group L constitute an optical mechanism that projects the mirror in front of the subject image and guides the light incident on the subject image to the photoreceptor. .
As a variation of the embodiment of the invention shown in FIG. 1, instead of arranging the lens group L between the third mirror M2 and the second mirror M3, and the mirror M2. FIG. 2 is a principle diagram showing another embodiment of the present invention.

The difference from the case in FIG. 1 is that the second mirror M3 is removable, and the rest is the same. For example, when photographing a sunset sky or other celestial bodies, it is possible to directly measure the amount of light from the light source by removing the second mirror M3 from the front of the photoreceptor D. This method allows accurate photometry. It becomes possible. Since the present invention is configured and operates as described above, according to the present invention, the light incident on the subject from close range to infinity can be accurately measured by the incident light method at the photographing position, that is, the camera position. It became possible to measure

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, and FIG. 2 is a schematic diagram showing another embodiment of the invention. M,...First mirror, M.

Claims (1)

[Claims] 1. A first mirror that reflects the subject, a photoreceptor provided near the first, a second mirror provided in front of the photoreceptor, and the first mirror.
a lens group located between the second mirror and the second mirror and used for focusing; a third mirror that projects a mirror and guides the light incident on the subject image to the photoreceptor; The incident light type exposure meter is characterized in that the light incident on the subject image is guided to the photoreceptor by the lens group and the third mirror for photometry.