JPS6011823A - Method and apparatus for relating depth of field in photography to setting of maximum usable lens aperture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Kanedokoro ■Sen 1 1. Yuriji Branch This invention relates to photography and cameras, and in particular to a method and method for determining an appropriate maximum usable lens aperture setting for a camera for a given depth of field. It is about the means.

≦・ In any one photographic exposure, only objects within a certain range of distance in front of the camera are sharply projected or "focused" onto the film plane. This distance range is the “depth of field”
It is called.

The amount of depth of field depends on four parameters: the focal length, or the distance from the center of the lens to the plane of the subject that has the sharpest focus; the focal length of the lens; the aperture diameter used; and the required sharpness.

In other words, the closer the object focal length is, the longer the focal length of the lens, the larger the aperture, and the higher the required image sharpness, the shallower the depth of field becomes. This property, often referred to as "differential focus," provides an excellent tool for emphasizing certain features and weakening others, or for other creative photography purposes. This characteristic is also one of the important concerns for most handheld camera photographers. This is because in order to minimize losses caused by camera movement while the shutter is open, it is important to use the largest usable aperture that provides the required depth of field.

Whatever the photographer's reasons for wanting to precisely control depth of field, there are three conventional ways to do this, each with strict limitations. These conventional methods are as follows: 1. Depth of field vs. aperture values are given in the form of numerous charts and tables, with values for each focal length of the lens, each film size, and each manufacturer and publisher. There are separate sheets for each sharpness criterion. These values are also based on the questionable assumption that the critical viewing distance for each photographic image should be equal to the focal length of the lens used multiplied by the magnification to produce the final image. Although this viewing distance is useful for reconstructing perspective images of the original scene, it is not the viewing distance used by most clairvoyants. Experience has shown that such charts and tables are rarely used.

2. Most photographic lenses are equipped with depth scale and aperture markings on adjacent rings around the lens body. The method of using these to determine the maximum usable aperture setting is detailed in the instruction manual that comes with each camera and lens, and is much more convenient and satisfying than using the charts and tables described above. It's something you get. However, this is still inconvenient and discourages all but a few photographers from learning to use it. Similarly, experience has shown that even after learning how to use the scale system printed on the lens body, most photographers ignore it.

Another reason why mark markings on the lens body are ignored is that the current state of the art trend towards macro and close amplification performance of lenses has already compressed the distance between marking markings to an inappropriate value, Because of this limitation, accuracy is no longer guaranteed. When using zoom lenses, the marking problem is so complex that many manufacturers no longer provide markings, and when they do, the markings are no more than vestiges of previous markings.

3. The third method of determining the aperture setting and providing the necessary depth of field is to ensure that the rendering of the subject at the near and far limits of the depth of field appears reasonably sharp for the intended image purpose. This involves the simple operation of looking into the viewfinder, decreasing the opening, and then stopping.

This method assumes that if the image appears sharp in the viewfinder, it will be reasonably sharp in the final print or enlargement, or that the photographer knows how to make any necessary aperture adjustments. It is said that This method ranges from difficult to impossible levels of entry into small apertures at low light levels.

One of the important objects of the invention is therefore that the minimum usable numerical aperture is determined by solving a simple equation given readily available parameters representing the conditions that exist when taking a photograph. The purpose is to provide a simple and easy formula.

Another object of the invention is to - include an indicator that is easy to see and read, and furthermore is easily manipulated to modify the different indicators on the calculator, and a maximum aperture setting that can be used for any given depth of field; The purpose is to provide a dial calculator that allows direct instructions.

Yet another object of the present invention is that it can be easily mastered and used by the photographer and can be used for a given depth of field in relation to different focal lengths of different cameras and different film sizes. It is an object of the present invention to provide a device with an index that allows instantaneous determination of maximum aperture setting.

The invention has other objects, features, and advantages, some of which will become apparent from the following description, including the above, and from the 17J ir+i. However, since the present invention can be implemented in various ways within the scope of the claims,
It is to be understood that the invention is not limited to the embodiments shown and described.

DISCLOSURE OF THE INVENTION In its broadest sense, the method and apparatus of the present invention utilizes known parameters observable by the photographer during a given photo shoot, such as sound and sound, and correlates these known parameters in a novel manner. and determines usable aperture settings for unknown parameters in the situation, that is, observable depth of field parameters. One aspect of the invention is that by solving simple equations in which known values are substituted and correlated, it is accomplished to provide the desired information, i.e., the minimum amount available. Ru. Of course, as the numerical aperture becomes smaller, the aperture diameter becomes larger and the aperture area becomes larger.

Another aspect of the invention is that the relationship between the parameters contained in the simple equation above can be used to provide an index placed on a relatively rotatable scale, thereby Each parameter of opportunity is selected from the index and correlated with another index on the scale, and the maximum available aperture setting is read directly from the scale or circular calculator.

More specifically, the present method and apparatus for relating the depth of field of a photograph to the maximum usable lens aperture setting include:
To the best of the inventor's knowledge, it is possible to accurately determine the correct aperture setting using a handy camera with any focal length lens;
The problem stems from the fact that there is no quick or easy way to provide the necessary depth of field.

Of course, for any given aperture setting, a formula exists for determining the expected depth of field at that aperture setting. The main constraint in attempting to calculate the minimum usable numerical aperture for the required depth of field is that all the relevant considerations are to determine the depth of field condition from the known numerical aperture, hyperfocal distance value and focal length. Due to the fact that it seems suitable for. What is unusual about this situation is that most photographers obtain depth of field conditions by simply observing the subject to be photographed. What is most important is the opening setting for obvious conditions. The photographer has to decide this and the available tables, graphs and formulas are not very helpful. It's hard to believe that even at this point in time, when all aspects of photographic technology are highly developed, there has not been much progress in precisely determining the optimal aperture setting for handheld cameras.

The huge handheld camera market is based on the popular appeal of cameras for personal use, and the largest portion of the market is based on so-called "bakacho" cameras, which are less complicated than those that can be controlled manually. The above point becomes even more understandable when one considers that the manufacturer's position is that fully automatic cameras are cheaper to manufacture than manually controlled cameras. It has been enhanced by technological developments in manufacturing.

As mentioned above, one of the purposes of the present invention is to provide the easiest, quickest, most convenient, and most confusing way to determine the maximum usable aperture setting (minimum usable aperture) when using a handy camera, especially a 35-frame camera. The goal is to provide a means that never fails. The inventors have long been dissatisfied with existing assumptions, formulas and methods related to maximum aperture and depth of field.
I succeeded in deriving a much simpler and more effective relationship between them. This new, novel relationship, which is surprisingly simple once you know it, is that the minimum viewing distance at which you can accurately see the sharpness of an image is directly proportional only to the size of the image and to the focal length of the lens used during the initial exposure. It is based on the assumption that it is not a product of image sizes.

In other words, according to the method of the present invention, any desired depth of field,
For any focal length lens and film of any size, it can be used to give the sharpness of all objects within a given depth of field when viewed from a distance no closer than the diagonal length of the entire uncropped image. If the maximum aperture setting (which is the same as the minimum usable aperture) is expressed by fw: fw = (m+]) x (+/5n - 1/5f) x f conversion 2
xi/2 (10 where: m = magnification, that is, the ratio of image size to object size; Sn - near field of depth of field; Sf = far limit of depth of field; FL - focal length of the lens used; U - use the diagonal length of the film; and Q - the sharpness constant consisting of the ratio of the minimum 1n field viewing distance or the diagonal of the entire image to the maximum allowed t1) random circle.

In the case of general use of a 35mm camera, Q = 1224 and the subject is not closer than 4 times the focal length from the center of the lens, so if we ignore the (m+1) factor in the above equation, the above equation becomes further as follows. :This relationship is 360# in the above formula.
If 30' is substituted for , it is expressed in feet. This is useful when you want to express depth of field in feet.

An example of using the above formula expressed in both feet and inches is as follows: Example 1 Assume a 35 Dragon camera with a 5(1+m(2”)) lens.

If a depth of field of 36" to 48" is desired, what is the maximum aperture setting available? Solution: 1- (360/36-360/48) x 2
” ;-(10-7,5) x 4 10 Therefore, the maximum usable aperture setting under the above conditions is f
It is lO.

Example 2 35+n camera, 35mm (1,4″) lens.

If a depth of field of 3' to 15' is desired, what is the maximum aperture setting available? Solution: fy-(30'/g'30'/15')
x 1.42-(10-2)x2 = 16 Therefore, the maximum usable aperture setting under the above conditions is f
It is 16.

It is important to note that methods for determining the exact limits of depth of field are not very accurate. In any given shooting situation, the photographer views the scene and determines the near and far limits of the desired depth of field within the complete image. In most cases, the photographer does not actually measure these distances, but estimates the distances according to his ability, and the inventor has found that this is sufficient. The change in image sharpness on each side of both limits is gradual and can be roughly evaluated by subjective assessment.

The above two equations are theoretically simple and easy to use when shooting at a certain distance, but when the photographer wants to take a different scene, it is difficult to take out a pencil and paper and calculate the equation each time. It is. Most shooting situations do not allow for the time required to solve the equations, and the photographer is not in the mood to solve the equations. Therefore, some other means is needed to determine what the photographer wants to know, that is, the maximum aperture setting that can be used for the observed depth of field, without having to solve any equations. To meet this need, the inventor has devised a dial calculator that can be held simultaneously in the photographer's hand. It allows photographers to quickly, almost at a glance, use any fixed depth of field, any camera, any focal length lens, without having to solve equations or use pencils or paper to solve problems. You can determine the maximum possible aperture setting.

Referring to the drawings, and in particular to FIG. 7, a cross-section of the dial calculator of the present invention is shown. Due to the structure of the calculator, the outer circular edge 2
It includes a circular base disk 72 defined by ', which is made of any suitable material such as paper, cardboard, plastic, metal, etc. The base disk has any suitable diameter, for example from 2 to 4 inches or more, and is provided with a central opening 3 for receiving a stem 4 of an eyelet 6 which allows rotation of the parts of the assembly. As shown in FIG. 3, the base disk 2 has a surface 7 on its back side, and an annular region or annular surface area designated by the number 8 is defined near 2 degrees of the outer circular circumferential surface thereof.

The annular region or annular surface area 8 is bounded on its outer circumferential side by the outer circular edge 2' of the base disc and on its inner circumferential side by an annular band 8'', which has an equal arc length of 15 mm as shown. divided circumferentially into 246 individual segments, each arcuate segment corresponding respectively to 246 concentric arcs of rotation around the central opening 3.The annular segment band 8'' is further divided into a second annular region. In other words, it is surrounded by an annular surface area 8'', the inner periphery of which forms a circular line 9 concentrically arranged on the surface 7 with the center opening 3 as the center. base disc edge 2
radially extending towards 8.8" to form the starting point for the interrelation of the individual zones (15), here designated by the numbers 10 to 24, each with an index 25" on the annular region 8.8".
．． 25' is printed to indicate distances representing both near and far limits at a constant depth of field. The mark 25 on the outside or first area represents the limit distance from 2 feet to infinity in feet, and the mark 25° is 12 to 24 as shown.
The limit distance in inches is expressed in inches. Therefore, the third
The zone indicated at 23 in the figure lies between a near limit of 15 feet (15') and a far limit of 30 feet (30°), as defined by the discrete arcs of the annular band 8 that define this zone. It does not represent the depth of field of the image, but includes the arc length of the outer region 8.

Thus, the depth of field may include only one zone or several zones in a given shooting situation.

For example, the depth of field is 5 feet (5゛) for the nickname-shaped sinking.
It has a near limit of 10" and a far limit of IO feet (10").

Under such circumstances, the depth of field includes three zones, namely 19, 20 and 21, as is clear from FIG. When using a dial calculator, the photographer needs to assess the scene to be photographed and determine the near and far limits of depth of field desired for the composition of the scene. This assessment is made in feet or inches for the near and far limits of the selected depth of field. Next, the number of depth-of-field zones (or partial zones) included in the composition of the scene is determined by using a portion of the distance limiting index in the region 8 or 8'.

Once this information is obtained, the photographer turns the dial calculator to expose the face plate or disc 26 (FIG. 7). This disk, also of any suitable material, is circular and includes an aperture 27 formed in the disk to provide a window or aperture radially displaced from the central aperture 3, through which the intermediate disk 29 (fourth Figure) top surface 28
I can see it. Both disks 26 and 29 are attached to the eyelet 6 so as to be rotatable relative to each other. The top open guide disc 2G is cut over part of its outer circumference, giving an arcuate zone 31 of slightly smaller diameter than the outer circumference 32. The arcuate zone 31 includes an edge 33.34, a line 35.36, an arcuate line 3
7 and an outer reduced radius outer circumference 38 .

As shown in FIG.
．． An index 41 consisting of 4.6.8 and 11 is displayed as a mark, and these numerical values are determined by an arbitrary fixed value set in the zone 10-w24 provided on the back side 7 of the disc 2 shown in FIG. 3, as described above. Represents the number of zones included in the depth of field range. The use of these numbers will be discussed below. Reference is now made to FIG. 4, which represents the top surface 28 of the intermediate disk 29 and shows that the outer periphery of the disk is marked by a radially extending circular series of lines 42 containing 24 It shows that it is divided into equal sections.In the figure, only one line is marked with an arrow, but this is only to make the explanation easier to understand. At the opposite inner end, there is provided an index 43 displaying a numerical value representing the focal length of a predetermined lens.In the illustration, the focal length of the lens represented on the disk 29 is in the range of 18 to 400 am. .

Referring to the arrow numbered 44 above, this constitutes an index mark used to relate the rotational position of the disc 29 to the film size used. As shown by the index 46, the film size is indicated on the base disc In 47'2, and consists of film size indications from 8 fins, 105 m, 35 m, to 70 mng,
It is formed in an arcuate pattern located just outside the outer periphery of the intermediate disk 29, but is printed on the surface of the base disk 20.

Once the above adjustments or settings of the intermediate disk 29 have been made for a particular camera, there is no need to re-set them as long as the same camera is used with the same film.

By setting the intermediate disk to indicate the film size in use and assessing the scene to be photographed, the desired depth of field and degree are determined by the three depths of field or zone 19 as described above.
The photographer, aiming to be between 5 and 20 feet including ~20, then ha l-[! 4 Installed top disc 26
Rotate the window 27 to a position -1 opposite the focal length of the camera you are using. In FIG. 1 the number "50" appears in the window or aperture 27 - this is the f of the lens being used.
It point i? Mouth I) 11 indicates that there are 50 cranes. After this setting, the photographer, who knows that the depth of field includes three depth of field zones, glances at the number "3" falling in the arc-shaped area 31 on the surface disk 26, and reads the number "3".
You can see that it is facing the numerical value: 11".

The latter number "1" represents the lowest numerical aperture that can be used under the given conditions to achieve sharp focus for all objects within the indicated depth of field. Referring to Figure 5, the number "11" represents the index 4 representing different numerical apertures.
8, which is selected in relation to the number of depths of field represented in the arcuate area 31 of the surface plate or disc 26 and indicated by the indicator 41.

Looking at the indicia 48 forming a circular array adjacent the outer periphery 49 of the top disk 26, the numbers are equally spaced from each other, but the values are doubled every second.

For example, the number "2" is between the numbers "1.4" and "2.8", and "2.8" is twice the value of 1.4. This same relationship applies to the surface disk 26. A series of numbers forming an index 41 in an arcuate region 31 is maintained.

As is clear from the above, the expression or equation for 1iij, ple and the implementation of this relationship into a dial calculator that illustrates and describes the relationship between Quantity 1" is an important point for the simple proportional relationship between the numbers. Many examples show the use of the dial calculator and the depth of field conditions when using the zone system described above and the usable It should show a proportional relationship between the minimum numerical aperture.Here, we will solve the previous example,
For the purpose of comparison between the formula used for the formula and the dial calculator, the same conditions used for the formula are applied to the dial calculator.

Example lA A 35mm camera and a 50ffl (2”) lens will be used.

If a depth of field of 36" to 48" is desired, what is the maximum aperture setting available? Solution: From Figure 3, 36" to 48" - about 2-1/2
zone. Therefore, 2-1/2×22=10, and the minimum usable numerical aperture is 10.

] Column 2 A If you have a 35-liter camera, a 35-inch (1,4") lens, and require a depth of field of 3° to 15", what is the maximum usable aperture setting? Solution method 2 3゛ ~1
5' = 8 zones.

Thus, a glance at the dial calculator shows that zone 8 is opposed by the number "16", indicating that the maximum usable aperture setting for the above conditions is 16.

Of course, since there are no numbers on the scale between the integers shown, it is necessary to extrapolate the closest usable maximum aperture setting as the case may be.

[Brief explanation of the drawing]

Figure 1 is a plan view of the completed dial calculator. FIG. 2 is a plan view of the base disk of the dial calculator separated from the rest of the structure. FIG. 3 is a plan view of the back side of the base disk shown in FIG. 2. FIG. 4 is a surface plan view of an intermediate dial classified as a lens dial. FIG. 5 is a plan view of the base disk with two intermediate disks stacked one on top of the other, showing the means for correlating the lens type and film size used. FIG. 6 is a plan view of the opening 1 guide disk separated from the rest of the structure. Figure 7 is a cross-sectional view through the center of rotation of the dial calculator.
The thickness of each element is exaggerated for clarity of drawing. 2-Base disk, ゛6-Central coupling means (C1-th)
, 7-Base disk back surface (first surface), 8-Base disk outer circumferential annular area (surface area), 8゛ depth of field interrelated zone, 25.25=-depth of field distance, 26'-surface play 1 ~ or disk , 27-Eccentric aperture, 29-Intermediate disk, 41-Depth of field zone index, 43-Lens focal length index, 46-Film size index, 47
-Base disk top surface (opposite surface), 48-- Numerical aperture (setting) index. -127- FIG, 5 FIG, 7 Procedural Amendment (Manmin) 1. Indication of the case 1939 Patent Application No. s 809 s
+i'f3, Relationship with the person making the amendment Applicant's name George A. Wallis4, Agent

Claims (9)

[Claims] (1) In a dial calculator for determining the usable aperture setting of a camera lens when a parameter representing the depth of field in a certain shooting situation is given: a. A distance representing the depth of field is displayed on one side; a series of numbers spaced apart along the outer periphery of the base disc;
It defines a zone associated with the depth of field measured by the difference between two numbers giving a pair, and further consists of a series of numbers indicating the aperture setting of the camera lens on the other side,
a base disk having an index in which the aperture setting numbers are arranged in an arcuate arrangement adjacent to the outer periphery of the base disk;
b. an intermediate disk rotatably superposed on said base disk, arranged in a circular arrangement and having an index representing the focal length of a series of camera lenses in millimeters; C0 rotatably superposed on said intermediate disk; matched,
a surface disc containing an arcuately arranged index consisting of a series of numbers representing zones of depth of field, the surface disc having an aperture that is selectively adjustable by rotating the surface disc relative to an underlying intermediate disc; on the base disk opposite the zone numbers indicated on the surface disk determined by the number of intervals defining the zones on the base disk by displaying through said aperture the focal pressure 1til of the camera lens in use. a dial calculation consisting of the combination of: a display indicating the maximum available aperture setting; and d. means centrally located on said base disc, intermediate disc and surface disc and rotatably coupling said discs together; vessel. (2) The base disk has indicators consisting of different types of film sizes on the side including the aperture setting indicator, and the film sizes are arranged in an arc on the base disk concentrically with the outer periphery of the intermediate disk. , while a lens focal length indicator on the outer periphery of the intermediate disc is selectively adjustable by rotating the intermediate disc, such that the indicator is positioned opposite one of the film size indicators. Combination of the first range term. (3) The set number of apertures on the base disk are equally spaced apart, and the arc-shaped numerical arrangement representing the depth of field zone on the surface disk is arranged concentrically with respect to the set number of apertures. Combination of item 1. (4) In a method for determining the maximum usable aperture setting of a camera lens by determining the minimum aperture usable in any given shooting situation: a. near and far depth of field of the scene to be photographed; converting the near and far limits of the selected unit of measurement into a measurement unit representation of the depth of field between the near and far limits; b. dividing the depth of field into a selected specific unit of measurement; measured 1
and C0 by multiplying the number of depth of field zones determined above by the square of the diagonal dimension of the camera lens. said product, expressed as , equals the minimum usable numerical aperture of the scene to be photographed, which gives the maximum usable aperture setting of the lens. (5) In a dial calculator for determining the usable aperture setting of a camera lens when a parameter representing the depth of field in a certain shooting situation is given: a. Annular surface area limited on the first surface in a circular base disk having: 1) means cooperating with said annular surface area to visually divide said annular surface area into a plurality of arcuate zones of equal length; 2) means cooperating with said annular surface area; and an index representing a linear unit of measurement associated with distance at the near and far limits of depth of field in relation to a camera lens, comprising a series of numbers spaced apart along said annular area and varying in numerical value. ,
This allows the depth of field indicated by the index and expressed mathematically by the numerical difference between the near and far limits to be visualized as a finite value expressed in the form of the number of zones or subdivisions of zones included in the depth of field. 3) The circular base disk has on its opposite side an indicator consisting of a series of numbers indicating the aperture setting of the camera lens, and the aperture setting number is indicated by an arc-shaped indicator adjacent to the outer periphery of the base disk. be arranged in an array; b. rotatably superimposed on the base disk on the side containing the number indicating the aperture setting of the camera lens;
an intermediate disk arranged in a circular array and having indicators representing the focal lengths of the series of camera lenses in millimeters; C0 a series of numbers rotatably superimposed on said intermediate disk and representing zones of depth of field; a surface disk containing arcuately arranged indicia consisting of an aperture selectively adjustable by rotation of the surface disk relative to an underlying intermediate disk, through which the camera in use can be mounted; By displaying the focal point W1 distance of the lens, the maximum usable aperture setting is displayed on the base disc opposite the number shown on the surface disc representing the number of zones of depth of field; and d, said base. A dial calculator comprising a combination of: a disc, an intermediate disc, and a means centrally located on a surface disc for rotatably coupling the discs together; (6) The means for visually dividing the annular area into a plurality of arcuate zones having equal arc lengths comprises an annular band defining the inner circumference of the annular area, the annular band having an arc length of 24°. 6. The combination of claim 5, wherein the band and toroidal area are divided into 15 visually distinguishable zones by being divided into discrete segments having a diameter. (7) A second annular surface area is provided on the same side as the first annular surface area on the base disk, and the second annular surface area is arranged concentrically with the first annular surface area. Combination according to claim 5. 8. The combination of claim 5, wherein said indicator representing a linear unit of measurement includes a number and a dividing line to assist in extrapolating a distance indication located between two adjacent numbers. (9) The above series of numbers on the circular base representing the aperture setting of the camera lens starts from the minimum value and increases gradually to the maximum number, so that each number starting from the third in the series is equal to the immediately preceding number. Claim 5 which is twice the previous value
combination of terms. 0 [Il A patent in which the surface disk is approximately circular and includes a large-diameter arcuate portion and a relatively small-diameter arcuate portion, and the indicator is displayed on the relatively small-diameter arcuate portion based on the number representing the depth of field zone. Combination according to claim 5. OO The combination of claim 5, wherein the indicia on said intermediate disk are uniformly spaced apart adjacent its outer periphery, and radially extending indicia marks correspond to respective numerical values.