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Scheimpflug-Patent.Pdf by Harold M. Merklinger Scheimpflug’s Patent as published in Photo Techniques, Nov/Dec 1996. Many large format photographers will know of the "Scheimpflug Principle", and a few will be aware that Theodor Scheimpflug of Austria is the person after whom the principle is named. But it will probably come as a surprise to most to learn that Scheimpflug himself disclaimed inventing the rule that now bears his name. The Scheimpflug Principle (or rule or condition) provides guidance on how a camera lens and/or back should be tilted when focusing upon a plane that is not parallel to the film. This short article is intended to provide a little historical background and Figure 10 of Theodor technical information about Scheimpflug's 1904 British Patent Scheimpflug and his patent. (GB 1196/1904) illustrates how the If Scheimpflug did not invent this optical system of a single compound rule, who did? Scheimpflug cites only objective lens is constrained by one reference, and that is to the British three geometrical principles. In Patent of Monsieur Jules Carpentier of today's language, A represents the Paris. In 1901 Carpentier had patented subject plane, FI the front focal an enlarger for correcting converging Jules Carpentier's 1901 British plane of the lens, HI the first verticals. Carpentier made this claim: Patent (GB 1139/1901) contains principle plane (nodal plane) of the "I have investigated the law which four drawings, Figures 1 and 2 of lens, HII the second or rear nodal governs the correlation between the which are shown here. This is his plane, FII the rear focal plane, and B inclination of the plane of the negative enlarger for correcting converging the film plane. The hinge line and and that of the sensitized surface to that verticals. The movements of the reciprocal hinge line are noted g1 of the optical axis of the lens...and I plate holder and the paper holder and g2 respectively. MI and MII find that the relationship is this:—If the are constrained to obey the represent the split Scheimpflug line two planes are sufficiently prolonged principle we today call "the needed to describe the behavior of they must intersect in the plane Scheimpflug Rule" a 'thick' lens. perpendicular to the said axis and passing through the optical center of the introducing the term "the Scheimpflug example, believe that Henry Ford lens." Carpentier's apparatus for Rule" to describe the optical condition invented the motor car? Enthusiasts maintaining this condition is shown in first described by Carpentier. Radford knowledgeable about automobiles will (his) Figures 1 and 2. further illuminates the life of the usually name Gottlieb Daimler and/or Despite understanding of the Captain Theodor Scheimpflug of Karl Benz of 1885, but Siegfried "Scheimpflug Principle" as early as Vienna, and how he came be interested Marcus of Vienna and George Brayton 1901, knowledge of the principle and in the alteration of perspective in of Boston demonstrated vehicles the association of the principle with existing photographs. Radford points to powered by internal combustion Scheimpflug have been slow to the two early twentieth century British engines as early as 1875. In the field of develop, especially outside Europe. The patents awarded to Jules Carpentier of optics, it has also recently been brought 1951 book Lenses in Photography by Paris and Theodor Scheimpflug of to light that the "Schmidt Rudolf Kingslake notes that "when a Vienna. camera"—utilizing a spherical mirror lens is used to form an image of a small I was recently able to obtain copies and corrector plate—was actually sloping object, the object plane, the of these patents; they prove most invented in the form of a projector by image plane, and the median plane interesting. In his 1904 patent, G. H. Kellner for possible use in through the lens all meet together at a Scheimpflug notes that the optical automobile headlights. common point." But Kingslake principle we have come to call "the Carpentier is not clear on how he describes his proof of this principle as Scheimpflug Rule" is "well known". came to make his discovery, but there is approximate, and one could cite Indeed he credits Carpentier's 1901 some reason to believe that his numerous books on view cameras Patent as being the pinnacle of it's observation was empirical, that is, printed in North America up to the earlier application. based on experiment. Scheimpflug 1980s that show diagrams violating the One could make a good case studied the subject in considerably rule. therefore to rename the "Scheimpflug greater depth, describing not only the According to J. Radford, writing in Principle" the "Carpentier Principle". It use of single lenses, but multi-lens, the British Journal of Photography, the is not unusual in the field of inventions mirror, and mixed lens-mirror optical German publication International for public credit to be attributed to the systems for achieving almost any Photo Technik is responsible for 'wrong' inventor. How many people, for conceivable perspective distortion or www.mr-alvandi.com PARALLEL-to-FILM (Hinge Rule) REAR FOCAL (Reciprocal Hinge Rule) LENS PLANE PLANE FILM (hI to g1) (F ) PLANE LENS PLANE II (B) (H) PARALLEL-to-PSF FRONT FOCAL RECIPROCAL LENS PLANE f (h to g ) f PLANE (FI) HINGE LINE II 2 (g2) SUBJECT PLANE or SUBJECT PLANE or SUBJECT PLANE or (A) (A) (A) PLANE OF SHARP FOCUS PLANE OF SHARP FOCUS PLANE OF SHARP FOCUS FILM PLANE HINGE LINE (B) LENS PLANE (g1) LENS PLANE SCHEIMPFLUG LINE (HI) (HII) (M) Scheimpflug's fourth principle can be considered as two separate rules as Scheimpflug's third principle is illustrated here. The term "hinge rule" is not due to Scheimpflug, but this illustrated here in relation to a view aspect of Scheimpflug's fourth rule describes how the plane of sharp focus camera. It is identical to Carpentier's (A) rotates about the hinge line (g1) as the back of the camera is focused. The observation published three years "reciprocal hinge rule" describes what happens as the back of a camera is before Scheimpflug's patent. tilted about a suitable axis (g2) in the rear focal plane of the lens (FII). correction for an existing negative or in a mathematical sense, a perspective rule...—is so simple, it seems unlikely print. representation of the scene with the to me that it has not been documented Accompanying this article are front nodal point of the camera as the somewhere." I should have looked at several diagrams illustrating center of projection. Rule No. 2 is that Scheimpflug's patent! Scheimpflug Scheimpflug's principles and two of the the image of a plane is itself a plane. states: "..if the counter axes...of the two special cameras he designed. Principle No. 3 is the one that has come perspective images...are determined by It should be noted that neither to bear his name. These first three placing through the two nodal points...of inventor appears to have been interested principles are described in the patent as the objective, planes parallel to the two in applying the technique to the taking "well known". Scheimpflug's new image planes..., and causing the former of the original photograph. Rather both contributions commence with his planes to intersect the image planes, gentlemen concentrated on cameras or Principle No. 4, to be described in the then the counteraxes are always situated enlargers used to rectify the distortions following paragraph. Principles 5 and in the focal planes...of the lens system." present in previously taken beyond relate to the use of mirror These words are nearly photographs. They were concerned lenses, and optical systems having more incomprehensible, but they actually exclusively with subjects that really than one mirror or lens. (Note: describe two rules of optics: what I were flat planes. Neither patent Scheimpflug did not actually number called the hinge rule, and, what I called describes how to set-up a camera for the his new contributions; only the the reciprocal hinge rule. This double original photograph, although the established principles are actually rule, Scheimpflug's fourth principle, optical theory described is applicable to assigned numbers in the patent also leads back to Principle No 3, the that problem. And neither patent offers document.) Scheimpflug principle, as a corollary! any explanation of depth of field. In the preface to my book Focusing Perhaps surprisingly, we actually Theodor Scheimpflug makes the View Camera, I stated "..this have in Scheimpflug's Principles Nos. 3 reference to several optical principles. rule—which I have called the hinge and 4, three rules such that any two of Principle No. 1 is that a photograph is, them are sufficient to solve the lens equation unambiguously. What this means is that neither the Scheimpflug PARALLEL-to-FILM LENS PLANE Principle alone nor the hinge rule alone provides enough information to solve a = arcsin { f } J the view camera focus problem. Together, they do. f Equally well, we could use the Scheimpflug Rule and the reciprocal hinge rule to solve the problem. Or we a J SUBJECT PLANE or could use the hinge rule and the PLANE OF SHARP FOCUS reciprocal hinge rule. Any two of these three rules will suffice. HINGE LINE Each of the three rules requires three plane to intersect along a single One of Scheimpflug's proposed common line. The planes in each rule The view camera photographer cameras is shown in his Figure 19. are either shared with, or parallel to, the can use the hinge rule alone to Note how the lens is focused by planes in the other two rules. All determine the amount of lens tilt swinging it about a pivot at the together, for thin lenses, we have seven needed.
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