DE3410835A1 - METHOD AND DEVICE FOR CORRELING THE PHOTOGRAPHIC SHARPENING DEPTH WITH AN APPLICABLE MAXIMUM SHUTTER OPENING ADJUSTMENT OF A LENS - Google Patents

Description

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Method and apparatus for correlating photographic depth of field with an applicable maximum aperture setting of a lens

The present invention relates to photography and cameras and, more particularly, to a method and means for Determination of the suitable maximum usable lens aperture setting of the camera for a given depth of field or a given depth range.

In any photographic exposure, only objects within a limited distance can be in front of the Camera focused on the film plane or focused on it. This distance range is called the "Depth of Field" known as the "Depth of Field" or "Depth of Field". The extent of the depth of field depends on four Parameters, the focal distance, i.e. the distance between the plane of the object and the center of the lens at the sharpest Focus, the focal length of the lens, the aperture or opening diameter used and the required degree of sharpness.

Put in another way this means that the closer or The smaller the focal distance, the longer the focal length of the lens, the larger the aperture or opening and the sharper the image requirements, the lower or smaller the depth of field or depth of field. These Property is sometimes referred to as "differential focus" and makes an excellent tool either to emphasize certain properties or features and to push back or for others creative photographic purposes. This property or characteristic is also a source of major concerns Most of the photographers who hold their camera by hand because it minimizes the risk of exposure

image sharpness losses caused by camera movement with the shutter open, it is essential that to apply the maximum usable aperture or opening with the provision or specification of the required Depth of field is consistent.

Whatever the photographer's reasons for wanting a precisely controlled depth of field, there are three conventional methods of doing this, each of which has its strict limitations β These conventional Procedures are as follows

1, In a large number of maps and tables, the aperture values are plotted against the depth of field provided, for each lens focal length, for each film size and for each individual Sharpness criterion of a manufacturer or publisher is provided a separate sheet is »In addition they are based on the questionable assumption that the critical viewing distance for each photographic image is the same as the focal length of the Lens multiplied by the degree of magnification contained in the creation of the final image should. This viewing distance is correct for recreating the perspective of the original scene, however, it is not the viewing distance that most viewers want to use. the Experience has shown that these cards and tables are seldom used.

2. Most photographic lenses come with depth of field dials and device marks on adjacent ones Rings around the lens housing. The procedure for applying this to determine the maximum applicable aperture settings is well described in the instructions for use, which each Camera and lens are attached and there is a lot

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more convenient and satisfactory than the method discussed above which uses maps and tables. However, it is still quite unwieldy, so that all but a handful of "vom." Learning how to apply the procedure discourages. Again, experience has shown that most of these Photographers who learn to apply the scale system printed on the lens housing ignore it.

Another reason these markings on the lens housing are ignored is that the Trend towards macro capability and full capability in running lenses of the prior art, the already inadequate distances between marks so compressed and the number of marks so limited has that accuracy is no longer possible. The marking problem is like this with zoom lenses complex that many manufacturers are no longer providing this facility, and where it is provided it is Markings little more than rudimentary gestures.

3. The third method of determining aperture or aperture settings to establish depth of field requirements simply involves looking into the viewfinder and holding down the opening until objects are displayed at the near and far limits of depth of field for appears adequately sharp for the purpose for which the image is intended. This procedure assumes that if the image appears adequately sharp in the viewfinder, it is either adequately sharp in the final print or the final magnification is, or the photographer wants to know how to make a required aperture setting do is.

The method according to the invention and the device according to the invention use known parameters that are determined by the

Photographers at any given photographic activity are observable and correlate these known parameters in a new way to determine what is unknown under the circumstances, namely the maximum to use Aperture setting for the observable depth of field parameters. In one aspect of the invention this is done by solving a simple formula in which known values are substituted for and related to the information you want expressed in terms of the minimum applicable number of openings. This is of course to be understood as that when the number of openings or aperture number is smaller, the diameter of the aperture and thus the area the aperture become larger.

In another aspect of the invention, the relationships of relationships of parameters included in the simple formula discussed above are used to generate labels that refer to relative to one another. the rotatable scales, the parameters of any given photographic event being selected from the marks and correlated with other marks on the scales, and the maximum applicable aperture setting being read directly from the scale or a circular calculator.

One of the important advantages of the invention is that it is simple and easy to use Formula is given by which the minimum applicable aperture number is determined by solving a simple formula at which easily obtainable parameters can be set forth, at the time or at the point in time existing conditions of the photographic activity

represent.
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An advantage of the invention can also be seen in the fact that

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an adjustment dial calculator is created which contains easily readable marks on a bezel which can be easily manipulated to correlate different brands on the calculator such that you directly the maximum applicable aperture setting for each depth of field or each depth of field Show.

Another advantage of the invention can also be seen in the provision of a device which the carries brands correlated to different focal lengths of different cameras and different film sizes, and which can be easily mastered and used by the photographer when the maximum applicable aperture setting should be determined once for an entered depth of field.

The invention has other advantages and features or properties, some of which are combined with the foregoing from the following description and drawings. It goes without saying, however, that the invention is not limited to the illustrated and described embodiments, since they can be embodied or implemented in various forms within the scope of the appended claims.

From the individual figures of the attached drawings show:

Figure 1 is a plan view of the complete setting or dial calculator;

Figure 2 is a plan view of the rest of the structure removed basic disk or base disk of the disk calculator;

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FIG. 3 shows a plan view of the rear side of the base disk according to FIG. 2j

Figure 4 is a plan view of the front of the adjusting washer, as the lens

adjusting disc can be marked j

FIG. 5 shows a plan view of the base disk with the intermediate disk mounted on it, the Means for correlating the type of lens used with the film size used is shown are;

Figure 6 is a plan view of the rest of the structure removed aperture guide disk; and

FIG. 7 shows a section through the center of rotation of the setting disk calculator, the thickness of the various elements for the sake of clarity · - ·· ■ drives .shown.

The method and the device for correlating the depth of the photographic field or * depth of field with the usable maximum aperture setting, as far as I know, finds its cause or Emergence in the complete absence of faster and easier means of accurately determining the correct one Aperture adjustment for use with a hand-held camera of any focal length Generation of any required depth of field.

There are of course formulas with which the depth of field for any given aperture setting can be determined that can be expected with such an aperture setting »The main difficulty when trying to find the minimum

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Aperture number or aperture number for required depth of field comes from the fact that all related Formulas for determining depth of field conditions from known aperture numbers, hyperfocal distance values and focused distances seem to be established. The anomaly of this situation lies in that the vast majority of photographers can understand the depth of field conditions just by observing the too the subject to be photographed. The correct aperture setting for the conditions is unknown appear. These must be determined by the photographer and the tables, graphs and formulas available are one scant help. It seems incredible that such a highly developed state of the art as that which characterizes all phases of photography, for the exact determination of the optimal aperture settings contributes so little to photography with the hand-held camera.

This becomes more understandable when one realizes that the actually large market for hand-held cameras based on the general acceptance of the camera for personal use or purposes and camera manufacturers understandably believed that by far the majority of these cameras are desired on the market would rather be those that are operationally uncomplicated and "unthinkable" than those that can be controlled manually. These Position of manufacturers has been strengthened by technological advances in camera manufacturing, which make fully automatic cameras less expensive to manufacture than manually controlled cameras Cameras.

As indicated above, an advantage of the invention is that the simplest, fastest, least most disruptive and convenient means that

makes it possible to determine the applicable maximum aperture settings (applicable minimum aperture numbers) for hand-held cameras, in particular for the application of a 35 mm camera. After years of intense dissatisfaction with existing requirements, formulas and procedures related to maximum apertures and depths of field, IcIr ^{- derived} a much simpler and more correct relationship between these things or sizes. This new and surprising relationship, which is surprisingly simple once it is known, is based on the premise that minimum viewing distances for critical viewing of image sharpness are directly proportional to image size alone and not to the product of image size and focal length when performing the initial Exposure lens used should be.

Therefore, if, according to my method f .., we determine the applicable maximum aperture setting (that of the applicable minimum A ^ erturnummer corresponds) to produce sharper Image all objects within a given depth of field when viewed from one no closer as the diagonal length of the full and unadjusted image, then applies to each required » lent depth of field with every lens focal length and every film size

f _w = (m + 1). (i / S _n -1 / S _f ) -FL ² »1 / 2QU

where m = the magnification, e.g. the ratio of image size to object size, S _f = the far limit of the depth of field, FL = the focal length of the lens used, U = the diagonal length of the film used, and Q = a sharpness constant, which is the ratio of the critical minimum viewing distance, for example the full screen diagonal

to the maximum acceptable circle of confusion or confusion diameter mean.

For general use with a 35mm camera work with Q = 1224 and with objects coming from the lens center are at least four focal lengths away, we can then set aside the (m + 1) factor in the above equation and reduce this equation no.ch further to:

f = { 3 ^6Q "360" 2

This relationship can be achieved by substituting 360 ^fl there where. this quantity appears in the above equation, expressed by 30 'in feet. This is common or applicable when depth of field is expressed in feet. One foot equals 0.3048 m. 360 ·· in the above equation equals exactly 360 inches, with one inch equating to 2.54 cm.

An example of using this equation, expressed in both feet and inches, is the following:

Example 1:

A 35mm camera and 50mm lens are given (corresponds roughly to a 2 ^liter! T lens). If a depth of field of 36 "to 48" (equivalent to 36 »2.54 to 48 * 2.54 cm) is required, what is the maximum aperture setting to use?

Solution: f _w = (360/36 - 360/48). 2 ² = = (10 - 7.5) * 4 =
= 10

Therefore the maximum aperture value to be used is

- Manufacture for these conditions = f1O.

Example 2:

There are a 35mm camera and a 35mm lens (1.4 "lens) given. What is the maximum aperture setting to use when a depth of field of 3 ' up to 15 '(3 · 0.3048 to 15 · 0.3048m) is necessary?

Solution: f ^ = (30 · / 3 · - 30 '/ 15 ») · 1.4 ² = = (10 - 2). 2 =

= 16

Therefore the maximum aperture setting to be used for these conditions = fi6 "

It is important to note that the procedures to determine the exact limits of the depth of field are far from an accuracy «in any given photographic situation

2.0 the photographer the scene and determines the near and far limit of the desired depth of field in full Image. In most examples, the photographer is not actually measuring these distances, but is estimating them to the best of his ability and I have found it satisfactory. The change in the image sharpness on each side of these limits is gradual, the evaluation being one thing more subjective Valuation or estimation is.

While the above formula or equation is simple in its theory, and also easy to apply, is it for application in a given case of photographic activity when the photographer other aspects paying attention to the scene, far too much, to ask the photographer to take out a pencil and paper and work out the equation. Most

photographic situations do not allow the solution the equation required time and the photographer is not in the appropriate solving the equation State of mind. Therefore there must be other means by which the photographer can determine what he needs to know, namely the maximum aperture setting to be used for the depth of field that he can without realized the need to solve some equation. To satisfy this need I have devised an focusing wheel calculator that puts the means in the photographer's hand all at once through which he can quickly and almost at a glance the maximum aperture setting to be used for any given depth of field, for any camera, for any lens focal length, and without the requirement solving an equation; or using pencil and paper to solve the problem can determine.

Reference is now made to the drawings. In particular, FIG. 7 shows a cross section through the setting disk calculator of the invention, which structurally has a circular ^{base disk 2, defined in its configuration by an outer circular edge 2 1} , which is formed from any suitable material, for example paper, cardboard, plastic or even metal can be. The base disk can be of any suitable diameter, for example 2 to 4 inches (2 x 2.54 to 4. 2.54 cm) or even larger, and it is provided with a central opening 3 which is adapted to fit the stem 4 an eye 6 which unites the rotation of the various parts of the assembled unit. According to FIG. 3, the base disk 2 is provided on its rear side with a surface 7, in addition to its circular outer circumference 2 ^1, an annular surface area is defined

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The annular area or surface area 8 is defined on its outer circumference by the circular outer edge 2 'of the base disk, and on its inner circumference it is defined by an annular band 8' which is divided over the circumference into 15 separate segments of equal arc length, Each arc segment spans an angle of rotation of 24 ° concentric to the central opening 5. The subdivided annular band 8 ^{1 in} turn circumscribes a second annular area or surface area 8 "', the inner circumference of which is a circular line 9, which is on the surface 7 concentric to the central opening 3. A marking 9 'extends from the line 9 to the edge 2 ^{1 of} the base disk, which forms an initial reference point for the correlation of the total of 15 separate zones, which are designated here by the numbers 10 to, 24, with markings 25 and 25 'are printed on the annular areas 8 and 8' °, which indicate the distances that the near u nd represent the distant limit of a given depth of field. The marks 25 on the outer or first area 8 represent these distances, expressed in feet, from 2 feet to infinity, while the marks 25 'represent or define these distances, expressed in inches, from 12 inches to 24 inches. In this way, according to FIG. 3, the zone designated by 23 encloses an arc length of the outer region 8, which has a depth of field between a near limit of 15 feet (15-0.3048m) and a distant limit of 30 feet (30 ^β 0.3048m) represents as it is defined by the separated arcuate portion of the band 8 "which defines this zone.

This means that a depth of field can only or else be used in a given photographic situation encompass multiple zones. In a given situation

For example, a depth of field may have a near limit of 5 feet (5 x 0.3048 m) and a far limit of 10 feet (10 x 0.3048 m). As can be seen from Figure 3, under these conditions, the depth of field is three Zones, namely the zones marked 19, 20 and 2 * in Figure 3. All a photographer has to do when using the focusing screen calculator is to assess a scene to be photographed and to determine the near and far limit of the depth of field that he needs for the Composition of the scene desires. This assessment or rating is made in feet or inches to the near and far limit of the selected depth of field. Next, he takes a look at the distance-defining marks in the 8 or 8 ^{lf area} and determines the number of depth of field zones or sub-zones included in his composition.

With this information, the photographer turns the focusing dial calculator so that the face plate or disc 26 (Figure 7) is exposed. This disc is also made of any suitable material, is circular in configuration, and contains an opening 27 formed in the disc to define a window or opening through which the the central opening 3 'is displaced radially and through which the upper surface 28 of the intermediate disk 29 (Figure 4) can be seen. Both the disc and the disc 29 are rotatable on the eye or attached to the eyelet 6 and rotatable relative to each other. The top or aperture guide disk 26 is over cut back a portion of its circumference so that a curved zone 31 with a slightly smaller radius as the outer periphery 32 is provided, with the curved zone 31 through at opposite ends Edge portions 33 and 34, lines 35 and 36, a curved line 37 and the outer perimeter 38 with reduced Radius is defined.

According to FIG. 6, the upper surface 39 of the upper disk 26 is provided in the curved zone 31 with marks 41 which the digits or numbers 1, 1 1/2, 2, 3, 4, 6, 8 and contain, where these numerals represent the number of zones represented by any given depth of field as defined by zones 10 through 10 24 and, as can be seen from FIG. 3 and has been discussed above, also on the disk side 7 of the Disk 2 is determined. The way in which these numbers are to be used is explained below.

FIG. 4 shows the upper front side 28 of the intermediate disk 29 and shows that the outer peripheral part the disk by a circular series of radially extending lines 42 in FIG Sections is divided. In the illustration, a line 44 has an arrow head, but it is Done for the sake of clarity and will be explained later. Opposite the inner end of each of these lines is a mark 43 is provided in the form of a number which •. is the focal length of a given lens in millimeters expressed represented. In the illustration, the focal lengths are those represented on disk 29 Lenses from 18 mm to 400 mm. The arrow head 44 represents an index mark that is used to correlate the rotational position of the disc 29 with the size of the film used, as specified by the brand displayed on the upper front surface 47 of the base disk 2 and containing the designations of film sizes, which run from 8mm to 16mm, up to 35mm and up to 70mm and those in a curved pattern just outside the outer periphery of the intermediate disk 29, but on the front side of the base disk 2 are printed.

The previous adjustment or setting of the washer 29 is once in conjunction with a

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- taken camera and does not need to be done again as long as the same camera is used with the same film. Has he adjusted the spacer to indicate the size of the film being used and has determined, from an estimate or judgment of the scene to be photographed, that the desired depth of field is three zones of field depth, for example 5 to 10 feet (5 x 0.3048 to 10 x 0.3048m), including zones 19-21 as discussed earlier, the photographer next rotates the top disc 26 on the eye until the window 27 is opposite the focal length of the camera he is using . In FIG. 1, the number "50" appears in the window or in the opening 27 and indicates that the focal length of the lens or objective used is 50 mm. With this setting, and knowing that the depth of field comprises three zones, the photographer next takes a look at the number "3" in the curved area 31 on the front of the disk 26 and finds that the number "3" is the Opposite number "11", which represents the minimum diaphragm opening number or aperture number which can be used under the specified conditions to achieve a sharp focus of all objects within the displayed depth of field. Referring to Figure 5, the number "11" is one of a series of numbers which form marks 48 which represent various aperture numbers that can be selected in correlation with the number of zones of depth of field indicated by marks 41 which are in the curved portion 31 of the face plate or disc 26 are indicated.

The marks or numbers forming a circular field next to the outer periphery 49 of the upper disk 26 48 are evenly spaced, but their values double for every other number.

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For example, it should be noted that the number "2" is between the numbers "1.4" and "2.8", and that "2.8" is just twice the value of "1.4". The same relationship is in the series of numbers which the marks 41 in the curved portion 31 of the front panel 26 are maintained.

From the foregoing it appears, that the above formula or equation set forth and the satisfaction or execution of the relationships of that equation in that shown and described adjusting dial calculator the key to a simple and directly proportional Relationship between depth of field conditions and the minimum applicable provided for that depth of field Aperture number forms. A number of examples will illustrate the manner in which the shim calculator can be used and the directly proportional relationship between depth of field conditions and this Applicable or applicable minimum diaphragm aperture number or aperture number using the zone system set out demonstrate. For the purpose of comparing between the shim calculator and solving the The above examples used in the equation will have the same conditions as in the equation were also used when using the shim calculator.

Example 1A

Given a 35mm camera and a 50mra lens (2 "'lens or 2 inch lens). What is the maximum aperture setting to be used when a depth of field of 36 "to 48" (36 "to 48" or 36 x 2.54 to 48 x 2.54 cm) is required?

Solution; From Figure 3 it can be seen that 36 "to 48" corresponds approximately to 2 1/2 zones. That's why

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the result is (2 1/2) .2 = 10 and the applicable one the minimum aperture is f1O.

Example 2A

Given a 35mm camera, a 35mm lens (1.4 * 'lens or 1.4 inch lens) and a required depth of field from 3 'to 15' (3 feet to 15 feet or 3 x 0.3048m up to 15 * 0.3048m); what is the maximum applicable aperture setting?

Solution: 3 'to 15' corresponds to approximately 8 zones. That's why a look at the dial calculator shows the number "16" opposite the number of the zones corresponding to 8, indicating that 16 is the maximum applicable aperture setting for the given conditions is.

Because of the absence of numbers on the scales between d ^p n integers shown-it may of course sometimes be necessary to interpolate to the closest maximum adjustable aperture setting.

A method and apparatus for determining the applicable aperture setting of the Lens of a camera for a given depth of field, intended for use by photographers is. A formula was developed which is used in the display of the minimum applicable aperture number results when readily available parameters are used in the formula. On similar ones A circular calculator has been devised to provide the correct aperture number at a glance indicates that the depth of field should be applied to any depth of field expressed in either inches or feet is.

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In the foregoing and in the patent claims, the term lens means, in particular, an objective which is usually consists of several lenses and under indices, brands or markings are particular Understand the marks printed on them.

Claims (4)

Patent Attorneys Dipl.-Ing..H, W-f ic'smann, Dm> * l .-- * Phys. Dipl.-Ing. R A.Weickmann, Dipl.-Chem. B. Huber Dr.-Ing. H. Liska, Dipl.-Phys. Dr. J. Prechtel D / 20 8000 MUNICH 86 23rd MSfZ 1984 PO Box 860 820 MOHLSTRASSE 22 TELEPHONE (0 89) 98 03 52 TELEX 522621 TELEGRAM PATENTWEICKMANN MUNICH Mr. George A. Wallace 13695 üvas Road, Morgan Hill, California 95037 V. St. v. A. Method and apparatus for correlating the photographic Depth of field with an applicable maximum aperture setting of a lens Claims Setting wheel calculator for determining the maximum applicable aperture setting given camera lens parameters, which determine the depth of field of a given represent photographic situation, with a) a circular base disk (2) with marks (25, 25 ') on one side of the disk which indicate the distances, which indicate a depth of field, the marks (25, 25 ") having a series of numbers that surround the outer peripheral portion (8) of the base disc (2) arranged around at a distance from each other and at intervals are which define zones that are correlated to a depth of field given by the difference is measured between the two numbers that make up any pair of those numbers and with marks (48, 41) on the opposite side of the pane, which have a series of numbers (48) which indicate the aperture settings of the camera lens, the numbers (48) for the aperture setting in a curved area next to the outer circumference (2 ¹ ) of the base disc (2) are arranged; with b) an intermediate disk (29) which is rotatably arranged on the base disk (2) and marks (42, 43) which are arranged in a circular field and the numerical values of the focal lengths of a Represent series of camera lenses in millimeters; with c) a front disk (26) which is rotatably arranged on the intermediate disk (29) and in a curved one Box contains marks that have a series of numbers that represent depth of field, where an opening (27) is formed in the front panel (26) which, by rotating the front panel (26) is optionally adjustable in relation to the intermediate disk (29) below so that in the opening (27) the focal length of the camera lens used is displayed, with the applicable maximum Aperture setting on the base plate (2) opposite that indicated on the front plate (26) The number of zones is indicated by the number of zones defining the intervals on the base disk (2) is determined; and with d) a means (6) arranged centrally in the base disk (2), in the intermediate disk (29) and the front disk (26) for rotatably connecting the disks together. 2. The calculator according to claim 1, wherein the base disk (2) is on the one containing the aperture setting marks Page has marks that contain the size of different types of film, with the film size indicating marks in an arc region which is concentric to the outer circumference of the intermediate disk (29) are arranged on the base disk (2), and wherein an index mark (44) on the outer peripheral part of the Intermediate disk (29) can be selectively adjusted by rotating the intermediate disk (29) so that the index mark (44) can be placed opposite one of the marks indicating the film size. 3. The calculator according to claim 1 or 2, wherein the aperture setting numbers (48) are arranged on the base plate (2) at the same distance from each other, and with the curved range of numbers on the faceplate (26) representing the depth of field zones in relation to the aperture setting numbers are arranged concentrically. 4. Method of determining the applicable maximum aperture setting of a camera lens in any one given photographic situation by determining the applicable minimum aperture number, with the following process steps: a) In a selected unit of measurement, the near and far limit of the depth of field is to be photographed Scene is determined and the units of measurement for the near and far boundary in one expression in the unit of measurement the depth of field converted between the near and far limit; b) the so expressed depth of field is divided into one or more depth of field zones, the is defined by specially selected units of measurement; and c) it becomes the product of the number of so determined depth of field zones and the square of the diagonal dimension determined by the camera lens, the product expressed as a number equal to the applicable minimum The aperture number for the scene to be photographed is the applicable maximum aperture setting the lens delivers.