Recently I found in my old papers the following reviews of it from , which amplify my remarks. Van Nostrand Reinhold, , pp.. University of California, which dealt chiefly with theoretical considerations has long been out of print. This turns out to be rather a strange publication for what at first glance has the appearance of a technical manual. The pronoun I is in constant use, which is not customary in technical writing.

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Recently I found in my old papers the following reviews of it from , which amplify my remarks. Van Nostrand Reinhold, , pp.. University of California, which dealt chiefly with theoretical considerations has long been out of print. This turns out to be rather a strange publication for what at first glance has the appearance of a technical manual. The pronoun I is in constant use, which is not customary in technical writing. Lipton is the sort of writer who is able without the least embarrassment to write of one of his own amateur 8mm films as "one of the finest stereoscopic films ever made" he does not quote any independent testimony.

His background is that of a photographic journalist, and at the time of writing his practical experience of 3-D was limited to his own 8mm test films, projected on a 4ft screen. He gives illustrations of his camera and projection set-up. He has never seen a Russian 3-D film, or a British one for that matter.

Of the four integral stereoscopic movie cameras built so far, Lipton has illustrations of the two American ones, but he is unaware of the existence of the two European ones. He has however made a thorough search of the files of the U. This is the novel section of the book, and it certainly merits close attention from those who now and in the future will be working in the 3-D medium.

The Spottiswoode Analysis Apart from thinking it difficult for film-makers to understand, Lipton levels three charges at the Spottiswoode analysis: first, that they make the assumption that the eyes function like a rangefinder, by which Lipton means p.

To take the first charge: If we look at their chapter "On the Perception and Transmission of Depth" we find p. It is clear that they attribute the sensing of depth to the extent to which corresponding image points in the two eyes fall on either corresponding light-sensitive cells in the two retinas, or on neighbouring but non-corresponding cells.

Later p. This I believe is still the accepted explanation of binocular depth perception. To write as Lipton does p.

Whatever the mechanisms of depth perception, there is certainly no doubt that binocular parallax gives precise and accurate placement of projected screen images.

This is easily verified with stereo images from a pair of slide projectors, when the position of a forward image can be readily matched against a pointer held by a colleague. As the convergence of the projectors is altered, the stereo image position moves forward and backward, in strict accordance with geometrical theory.

Psychological Factors It is true that the mental interpretation of an image does not necessarily follow precisely its geometrical position because of psychological factors, and in particular that forward images which intersect the sides of the screen or to a lesser extent the top or bottom are held back by the conflict between the binocular information and the logical information that anything disappearing at the edge of screen, the stereo window, must be beyond that distance, or it would still be visible.

The Spottiswoodes were of course fully aware of these considerations, and the last section of their book is entitled "The Human Factor in Stereoscopic Transmission". In introducing this subject they write p. It is able to fit together information received from many different sources, shifting, comparing, rejecting, and finally transmitting to the brain a statement which is much more sophisticated than the first crude message which it received from external sense data. It may be that Lipton is here confusing the placement of the stereoscopic image with its mental perception.

Rays from the image and from the real world have both to pass through the process of perception. The requirement of the stereoscopic image is that its rays should simulate as closely as possible rays which could be expected to arrive from a similar object in the real world. This never occurs in the real world, so the eyes are not accustomed to it, and this is known to be a cause of headache. However there is a certain tolerance before the effort of fusing divergent image points becomes painful, which doubtless varies from one spectator to another, possibly to some extent related to the frequency with which they have viewed stereoscopic films.

Valyus does not describe the experimental work on which this figure of 1. This is in fact a large angle in stereoscopic terms, since the angular difference between convergence on the screen and the parallel condition amounts to 0. The extent to which divergent images, even when they can be fused, give rise to discomfort after extended periods of viewing has not yet been tested.

All stereographers seek to limit divergence to unimportant background points which the brain will not wish to scrutinise closely. Lipton himself writes: "Divergent homologous points can prove to be troublesome when shooting close-ups that have a distant background". Also: "To be compatible with the creation of a stereoscopic effect, image points should have the lowest possible screen parallax". And also p. This seems remarkably close to the Spottiswoode position, which we will quote shortly.

But the trouble is, as Lipton says a little plaintively, that "it is far simpler to do photography with large values of K screen Parallax than small values". Advocates of divergence are thus open to the charge of putting the convenience of the cameraman before the comfort of the spectator. Lipton says p. It is to be noted that the advocates of divergence on background points do not claim it to be advantageous, but merely that within certain limits it is tolerable.

Reduced Interaxial In practice, the only means of avoiding divergence on background points behind a close-up is by suitable reduction of the interaxial separation. Extreme close-ups require extremely small interaxials, so that a rig with zero-separation facility becomes desirable. And so we find that stereographers who do not have access to small-separation cameras argue in favour of divergence as desirable; stereographers with small-separation rigs on the other hand usually argue that divergent images should be avoided.

Lipton comes into the former category, since he tells us his 8mm rig had a minimum lens separation of 66 mm, about the human eye separation, and his later work has been done with the fixed-separation Stereovision lenses. But they also went on to say, in listing future development requirements, that "Much experimental work must be carried out to determine limiting values of divergence at different viewing distances which are acceptable without eyestrain".

Raymond Spottiswoode had responsibility for preparing and presenting the programme of 3-D films at the Festival of Britain exhibition. He therefore had the opportunity unlike Lipton of putting his films before a paying audience,, on a full-size screen, and taking sample polls of audience reaction.

He gave high priority to viewing comfort for the audience. Many people think it would have been in the better interests of the industry if later producers had concentrated more on viewing comfort and less on 3-D sensationalism. The first figures are recommended for use in scenes where the background will be subject to scrutiny; the second for scenes where the background is unimportant, a mere backing to significant foreground detail.

So the difference from the Spottiswoode position is again only one of emphasis. Unfortunately he has not numbered his equations, so it is sometimes difficult to know what previous result he is referring back to. Also, equations are sometimes carried forward incorrectly; as for instance the upper equation on p. A new mathematical nomenclature has been adopted for the various optical factors of image and object distance, lens focal length, interaxial separation, and so on. In some cases Lipton has followed Spottiswoode, in others preferred to use a different letter.

Very often he gets confused with his own nomenclature so that results become incorrect or incomprehensible. As an instance, in the top four equations on p. Errors Many examples of such errors could be given. Without labouring the point too much, here are a few. Diagram 3. Table 8. Quite a lot of detective work is needed to try to make sense of the argument. Twelve pages of depth-range tables are given, for 8mm, 16mm, 35mm and 70mm films, with 3 focal lengths for each film size, and a choice of five interaxial separations between 25mm and mm.

It will be seen that these tables are not of great practical use, since the range of five widely-spaced interaxial separations would not be adequate for anyone with a variable-separation camera.

Since Lipton tells us the only variable-separation camera he has used is his 8mm rig, with no separation available smaller than 66mm, the tables are anyway only suppositional.

Lipton in fact advises his readers to compute their own tables; the examples he gives may be regarded as a guide to one possible form of presentation. He declines to follow Spottiswoode in the use of reciprocal distance units, although this greatly abbreviates depth-range tables since the depth is then the same value for all object distances. The tables do not give any values for the required convergence in angular or other measure for the given lens separation and object distance.

Lipton seems to assume that convergence will be set by the primitive method of lining up an object at the required distance successively on the ground-glass crosslines of the two cameras. Stereoscopic depth tables are only valid for a single size of screen.

Shape Distortion One of the striking originalities of "The Theory of Stereoscopic Transmission" was the analysis of the shape reproduction to be expected of images viewed in a stereoscopic system. The authors pointed out that the depth magnification of an image, as compared to the object, would in general not be the same as the width and height magnification; they devised the concept of the Shape Ratio, which is Depth Magnification divided by Width Magnification, to assess the shape of the image; and they distinguished between scenes in which the shape reproduction would be constant throughout the scene, and those in which it would be nonlinear, differing in the foreground from the background.

The concept of the Shape Ratio has been found to answer well to the practical requirements of 3-D filming. It serves as a valuable guide in such tasks as the shooting of pack-shots for 3-D slide shows, where clients can be highly critical of any distorted representation of their products.

In 3-D TV commercials this can be expected to be an important factor. He does give a definition of Object Magnification, using the term to cover Width Magnification only; but he at once falls into the trap of confusing the stereo image size with the size of the 2-D screen image — the two are only the same when the image is in the plane of the screen.

At this stage, Lipton abandons his formulae altogether, falling back on vague generalisations — p. Anyone wishing to make tests of the shape characteristics of stereoscopic images I would strongly advise to work with 35mm slides, not 8mm movies. Slides are cheaper and simpler, the definition is much better, a much bigger picture can be projected, the convergence can easily be altered by swivelling the projectors, and every scene can be held on the screen as long as desired, whilst the image is examined from different viewing positions.

Since his 8mm days, Lipton has graduated to become a professional 3-D Expert, and took technical charge of the feature production Rottweiler, shot with Stereovision lenses. Lipton speaks highly of his work on Rottweiler, describing it as "one of the best shot stereoscopic films ever produced". Rottweiler has now had its initial showing, and subsequently seems to have been withdrawn from distribution. I asked recently in Hollywood what had happened to it; I was told it had been returned to the laboratories to have the stereoscopic errors corrected.

The historical sections arc fascinating, with many illustrations from early patents and amusing comments on their absurdities. One cannot doubt his intense belief in the future of the 3-D media.

The book has many diagrams, clear but rather poor in quality by comparison with the current standard in photographic books; the author has not attempted to provide stereoscopic illustrations as the Spottiswoodes did in an accompanying booklet of anaglyphs.

It will certainly find many readers, since it is now the only book available on the subject, and there is just now a great upsurge of interest in 3-D image processes of all types. But readers would be well advised to verify the comments on stereoscopic image position and viewing comfort against their own observations, since it is known that psychological factors which influence the mental perception vary between individuals, and we are by no means dealing with an exact science.

The book ends on a triumphant note. In his last paragraph, Lipton announces that on November 20th he completed the invention of a splendid new system for high-quality 3-D television.

Once again, we shall have to wait and see. ISBN Van Nostrand Reinhold Co. Reviewed by Stephen A. Benton, Polaroid Corporation, Research Lab. The current revival of interest in "3-D movies" is only the latest phase of a hundred-and-fifty-year history of attempts to bring the richness ol high quality "spatial imaging" to embrace three-dimensional imaging in its widest sense to bear on our everyday experience. Hopes for sustaining this revival lie in the more advanced photo-optical technology now more widely available and in the more sensitive and intelligent use of that technology, By drawing together a wide variety of historical, mathematical, and practical data, Lcnny Lipton works to provide a firm intellectual footing for independent film artists considering this enhancement of their medium.


Lenny Lipton

Education[ edit ] Lipton majored in physics at Cornell University after starting out in electrical engineering. A self-described "mediocre student", he only excelled once he found a field he loved. Lipton now urges schools to be more "accepting of eccentric people with a different point of view because we are the people who make the difference. Lipton on Filmmaking, a compendium of his magazine writings, was also published in He drew his own 3D comics using red and green crayons on tracing paper, which were viewed using primitive glasses constructed of cardboard tubes and magnifying lenses.


Foundations of the stereoscopic cinema : a study in depth



Foundations of the stereoscopic cinema


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