Dennis Couzin

Every student of cinema should know that what persistence of vision explains is completely different from what the Phi Phenomenon explains. They have only to consider that the projector requires a 2- or 3-blade shutter to reduce flicker because our persistence of vision is too short for projection with a 1-blade shutter, while this has almost no effect on our perception of motion because the number of frames per second remains 24. Persistence of vision is well understood. D. H Kelly (of Technicolor!) did excellent research in the 1960s and 1970s along with many others. The small residual flicker in movie projection contributes to the film aesthetic. Motion perception in cinema is poorly understood. There has been no solid research since Wertheimer's from 1912. It's of great importance for cinema. Besides practical questions like shutter angle, there is now an aesthetic divide between the 24 fps folks and the 50 or 60 fps folks, which might be swept away by the no-fixed-frame-rate folks.

Wow, I hadn't heard of Gigabitfilm. Their datasheet describes a very special film from a very special company. There is one detail that might trouble cine users. I think they wrote the explanation backwards. It is the Callier quotient in the high densities that needs to be high to significantly raise the printing gamma. Also it's surprising that such a fine grain film can have a high Callier quotient. But, whatever the explanation, the negatives appearing very thin on the light table means they will print with too low contrast in a contact printer. So cine film, which is generally contact printed, shouldn't be processed per Gigabitfilm's instructions. Then, since their developer is special, how will it function for pushing? What tonality will it yield? Cine usage wants diffuse density measurement, not specular. It would be nice if Gigabitfilm provided a diffuse density characteristic curve, but they think they know better. Their passion about film -- uranic, Simon? -- is unlike anyone's passion about video.

Tyler Purcell said "the final Pro Res HQ file looked just like this", so his is not a problem of the delivery codec.

Carl's latest post is quite wrong. It borrows ideas from Special Relativity, including light's velocity being the maximum, without following though. The denial of there being an exact moment dividing past and future is Special Relativity's denial of simultaneity. But I still am waiting for anyone who understands Special Relativity and also understands cinema to make any lucid analogy. Calculating that 16mm frames can't be transported in less than 2.542 e-11 seconds doesn't cut it. It says nothing about cinema, and nothing about time. The concept of persistence of vision is NOT based on the assumption of exact moments dividing past and future. Time could be quantized and then persistence of vision could be expressed as gaps of a single quantum or more being invisible. Indeed persistence of vision means that a high Hz flickering light appears constant. (It is why 24 fps projectors need two-bladed, or better three-bladed shutters.) Cinematic motion perception is something completely different. First described by Wertheimer's Phi Phenomenon, it requires a first still image and a second still image at definitely distinct times. Then what one perceives is a motion carrying the first image into the second image. The phenomenon requires that the two times not be too close. There's no fine dividing line presumed. I can't follow Carl's reasoning about space or time in cinema, especially when they're described as being in competition. Cinema is a temporal art, and cinematographers have temporal skills to match this. How good are the films of great still photographers? But also, how good are the still photographs of great cinematographers? The temporal skills aren't easily added, or subtracted. The durational aspects of cinema are more the work of editors. There is one funny place where space and time do compete: in video bitrate. One must sometimes decide between making, for example, 1280x720 60p or 1920x1080 24p -- two Blu-ray options with similar bit rates, there being no 1920x1080 60p option. Assuming that one is not hooked on the 24p cinema look, this comes to a choice between temporal smoothness and spatial smoothness. It's an aesthetic decision in which philosophy, physics, etc. have nothing to say.

The Sony A7S sensor is about 36 x 24 mm. This corresponds to the 35 mm still format. It is much larger than the classical 35 mm cine format of 18 x 24 mm. Assuming you use the whole width of these formats, the lenses used on the A7S must have 1.5× the focal lengths of lenses used on the cine camera to make comparable pictures. The larger image size gives the Sony an optical imaging advantage over a 35 mm cine format. Look at the performance data for the best cine primes. In particular, look at their MTF values at 40 c/mm. Compare the MTF values at 27 c/mm for high quality still lenses having 1.5× the focal length. You can expect lenses with 1.5× the focal length to put more total image information onto the 36 mm wide format than onto the 24 mm wide format. (The quick explanation is that while aberrations scale with focal length, diffraction doesn't.) Note the word "onto" in the previous paragraph. The Sony A7S sensor is 4240 x 2832 pixels across is not enough to reap the full optical advantage. Realize that it has a Bayer (or similar) pattern, so the pixel count is not for full-color pixels as in a 3-chip camera. The quality of 4K (or QFHD) that can be gotten out of the Sony A7S depends very much on what Sony's ARW 2.3 RAW is. One would like to get values for every pixel in the sensor, to the full bit-depth of the sensor, uncompressed. Can you get better than 8-bit data out of the Sony A7S? With color film one gets the full information from the three emulsions. No Bionz X processor! Like everyone in here, I've struggled to identify the key difference between digital video and film. I don't think it is in the color or tonality which often define the "film look". Provided the video camera's R,G,B spectral sensitivities are like a camera film's, video can closely match the output colors of film prints made from that camera film. Provided the video camera's dynamic range is decent video can closely match the film's tonality. One film scholar described the difference as "it's the light". That film scholar had studied physics! What did he mean? I doubt he meant that film projectors project each frame twice with the off time about equal to the on time. This means there's a little bit of residual flicker in the light (and also a slightly modified Phi-Phenomenon) in cinema. This an be simulated with 96 Hz projection. All films jiggle a little and many show small processing flaws. This leaves grain vs. pixelation as the key difference between digital video and film. It must be. Random grain is an eyeful. It makes every color look different, especially black. It uses mental energy. It makes motion look different, makes time flow differently. This helps explain the aesthetic differences between 8 mm, 16 mm and 35 mm cinema which have greatly differing graininess. Image sharpness is affected by the frame-to-frame grain. Whoever has made a still picture from a film frame knows that it looks much less sharp than the movie looks when running. Publicity stills from movies are seldom taken from the movies. I once did an experiment with making the video camera's pixel array move randomly from frame-to-frame You can download the experiment's results here, but I suggest first downloading the readme here. The jumping pixels changed the expression on the character's face. The rectilinear arrangement of pixels is simply anti-pictorial. People endured the lines in analog TV, but row & column digital is twice as perverse. It's beyond obvious "aliasing". It doesn't quite go away even with millions of pixels trying to swamp it. The digital image processing algorithms are double one-dimensional instead of honest two-dimensional, so they exaggerate the problem. Most paintings are on canvas, and many painters of finely detailed work have chosen fairly coarse canvas for it. Canvas, woven with its warp and woof superficially resembling the pixel array, is the ground of the painted picture. The analogy with video fails, because moving images look ridiculous on a static ground. Project a movie or video on a rough wall to see this. The random grain of film that functions as a dynamic ground for cinema, taking the canvas's role. You can fake grain and have a dynamic ground for video, but why not face the challenge of video as it is? Painters on canvas also painted on panels. The gessoed panel had essentially no grain. Real artists enjoy leaving the track.

Eventually reciprocity failure becomes significant and the calculation doesn't work. I've made 60 exposures and that did require a test. Making three exposures onto color film using fairly selective R, G, B filters is interesting. It essentially creates a new color film, with new color reproduction characteristics. You will not reduce exposure when using these filters but increase it, quite a bit. Think it through. The light transmitted by the three filters adds up to much less than full white light. For example, when using Wratten filters #29, #61, #47 the total is about 25% of full white light. Very crudely, because this ignores the peculiarities of the color film's sensitivities and balance, your three filtered exposures together are only equal to one unfiltered exposure through an ND 0.6 filter. So you must add about 2 stops on average when making each of the filtered exposures.

To add one more Bolex RX disadvantage. Its 130° shutter angle is significantly less than other 16mm cameras' 170° to 235°. This not only costs light for exposure but creates a different motion blur than the longer dwell cameras. Bolex movies have a greater tendency toward motion unsmoothness/stutter than other movies shot at the same frame rate. Bolex movies have a different "film look" than the norm. To add yet one more Bolex RX disadvantage. It is badly balanced -- too top heavy -- for hand held work. Bolex RX cameras were the only 16mm cameras I owned during my film years. They were loveable beasts with sensible build quality. But at core they were unwisely engineered.

Not just the f/1.3. The prism demands special RX lenses for f/2 too. Indeed Angenieux made a special f/2.2 12-120 for RX mount. The "about f/2 or f/2.8" clause cannot be made more precise, as explained in the 1987 article. To be safe, figure f/2.8.

Sorry, in my post #9 the first half of the quote is from Kenny S., but the second half is from Scott P. My post should have been addressed to Scott P. I'm used to being able to edit and re-edit what I write. This forum's anti-edit policy is maddening.

Unfortunately the Bolex RX cameras are RX-mount, not C-mount. Mechanically it's a C-mount, but there's a 9.5 mm thick prism between the mount and the film necessitating special RX-mount lenses. My ancient writeups about this: https://sites.google.com/site/cinetechinfo/atts/RXCrule_87.pdf and https://sites.google.com/site/cinetechinfo/atts/RXrule_76-78.pdf. To Scott: For fast lenses on the Bolex RX, you're limited to old rare ones. Why not benefit from the later advances in lens design? Film is an expensive medium. Why go cheap with the camera?

The Bolex pulldown mechanism is pathetic, but I think the film is static during its abbreviated 1/66 second exposure (at 24 fps). The inconsistency in its frame positioning should be routinely removed within the scanner's image processing. Of course the grain is very noticeable in 16mm, especially B&W. That is the hallmark of 16 mm cinema, and capturing the look of the B&W grain requires higher resolution scanning than capturing the image sharpness per se. Or are you going to shoot 16mm not to look like 16mm but as a cheaper way to capture the film look of the much less grainy 35mm. Then you should plan to de-noise the scan. Since film grain is frame-to-frame random 3D de-noisers work well on it.

Dirk, if you have a characteristic curve for 7276 (or 7265) developed in D96 to gamma 0.65 to 0.70, I'd be very interested to see it.

That probably best summarizes our disagreement. When I say time is used by some artwork I do not mean that some "conception of time" is used. Time, whatever it is, is used in one of two basic ways: either for the changes (e.g. motions) observable in the work or the durations observable in the work. I mean unembellished time derivatives or time spans, by the clock. Movies don't in general express any conception of time. When they do, it not any of the physicists' or philosophers', but one that is usually quaint and incomplete, but original: a conception of time that requires cinema for its expression.

When you view the wide format clips on YouTube you are probably too far from the screen for them to subtend the expected visual angle. And if you try viewing from closer you have the problem of binocularity. Perhaps monocular viewing from appropriate distance will work for you. (And make the surround dark, and the whole room.)

The fourth axis of Einstein-Minkowski's space-time is not spatial. In that space-time the four axes have the same units which can be indifferently length units or time units. You miss the main accomplishment of Einstein-Minkowski by denying this. As of 1905 (or 1908) we lived in space-time and there were no longer strictly lengths and times but space-time intervals. Feynmann put it: Yes, he uses the expression "geometrical entity", for there is some analogy with the geometry of the space-world, but the time axis isn't spatial. Space-time is 4-dimensional but it's not a hyperspace that extends an underlying 3-space, the way Euclidean 4-space does. Space-time is actually a mathematical oddity. Beyond being non-Euclidean it doesn't have a real-valued metric as required for topological metric spaces. It's a physicist's space for the physical world. And "space" assuredly does not imply spatial here. Physicists have phase spaces. Mathematicians have spaces for which there is no dimension. Etc. I'm surprised that Einstein-Minkowski space-time is being discussed in a cinematography forum without the usual yearning: Can't the admixing of space and time in cinema be elucidated through some analogy with space-time? I've never seen it pulled-off. Then better stick with Newtonian space&time and not bother with space-time. And I suggest not to so much rely on "represent" which implies second-take. We're dealing with conceptual models which underly.

I tried to make a distinction between durational art and temporal art, which you're partly accepting. Temporal art involves change, motion being a popular kind of change, but change in color works too, change in pitch, etc. Paintings are certainly excluded from the temporal arts. They might fade or crumple over years but it's not observable as change, nor is it intended change. Observability is required in any aesthetic feature of anything. Yes, what's observable by one person with normal senses might not be observable by another person with normal senses. In those rare cases we're unsure whether we have a temporal art work. But the role of the observer is quite different for durational artwork. Durational artwork is designed so its continuity through time, and the durations of its parts are aesthetically relevant. The observer must observe the work from beginning to end without pause to grasp its "temporal shape". The human mechanisms for change perception and duration perception are very different. There are surprisingly few psychologists who work on any kind of time perception. I luckily attended talks on aspects of this in Berlin last year: http://www.statefestival.org/program#statetalks-section Not all art is durational art. Movies, plays, dances, music, can be. Static arts like painting and written literature can't be, but also mobiles, video installations, etc. Neither temporal art nor durational art needs to be about time, or revelatory or expressive about time. They just use time in one or both of its modalities. I've enjoyed many more films than have taught me about time. One reason for making the distinction now is because durational art films might be disappearing, as, as Carl put it, film reverts to an orgy of movement. But even the exploration of cinematic time-flow, which does not require that it be durational art, is now endangered by developments in the medium, such as elimination of constant frame rate. Spatiality hasn't dominated over temporality in the arts. Music, drama and dance are ancient arts, and they will survive. Cinema has been especially non-revelatory or inexpressive about space. The major spatial discoveries were made in paintings, sculpture, architecture, dance. Hard-up 2.40:1 cinema is a case in point.

You seem to be confusing Minkowski diagrams, which as diagrams are of course spatial, with Einstein-Minkowski space-time. Minkowski famously said in 1908: Einstein-Minkowski space-time is not space. Space-time intervals are not distances. (How could distances take imaginary values?) You gained nothing at all by going ahead (from Newton) to Einstein, since you only find spatiality in every representation of time that falls short of your requirement of expressiveness. You also confuse abstract mathematical spaces with terrestrial space -- same word "space" but two different meanings. You seem to imagine a ruler when you write "dimension". What do you mean? In optics, images aren't that. In the mathematics I know, images aren't that.

Not quite right. You can't represent a pendulum's motion by drawing the arc. You have both dimensions representing space, none representing time. You've made a time-lapse photo instead of a movie. Spatial representation of the pendulum's motion requires three dimensions. Then your film strip which recorded the pendulum's motion is a puzzle. For the film strip is just two dimensional, but we just decided that a spatial representation of the pendulum requires three dimensions. The solution: film cheats the time dimension. A sequence of images, even made at 24 per second, is not an honest representation of time. We can cut the film strip into its frames and then stack them up like a deck of cards. This stack is the three dimensional spatial representation of the pendulum's motion required. But on close inspection there are spaces between frames in the stack. The stack isn't really a three-dimensional thing. For of course from a two-dimensional thing you can't make a three dimensional thing. But the stack looks three-dimensional, and that might do. The crux of the invention of cinema was the replacement of time with a discrete approximation to time. So please let's count our dimensions correctly. Four-dimensional world, 3 spatial + 1 temporal, is represented in a movie. The three spatial dimensions are compressed to two in the movie, by geometric perspective, and the time dimension is sampled in the film strip or other media, to be displayed in continuous time. The strip of movie film is not the movie. In fact the strip isn't quite the complete encoding of the movie. There's also the fps instruction in its metadata as it were. There's also the presumed 2-blade or 3-blade shutter that will determine how the movie looks -- how flickery the movie is. Not just how flickery it looks, but how flickery it is. There's also the spectral power distibution of the intended illuminant for projection. This is not the same illuminant as we use when we examine the film in our hands, so the colors we eyeball are not quite the colors of the movie. The movie is the display on the screen. It doesn't make a bit of difference whether the frames encode time in a strip or pop separately out of a corn popper. They're a discrete sampling of the time either way. It also doesn't make a bit of difference whether the frames are little rectangles of transparent film, or rectangles of gold, or lists of 0s and 1s in a digital file, so long as the display on the screen is correct. A movie-maker might pick up a camera and shoot some action and then instruct an editor how to cut it and finally show it without ever knowing whether the camera shot wide gauge or narrow, reversal or negative, or shot film at all -- it might have been video. Which "medium" did this movie-maker work in? The movie medium. So the movie is simpler than the recording. It's a 2+1 dimensional thing, 2 space and 1 time, wherein points have colors which keep changing, and when examined closer the changes are discontinuous according the the fps. These ideas rest on a Newtonian separation of space from time. Do not race ahead to Einstein-Minkowski space-time. Actually no aesthetic thought since 1905 has ever made a correct use of space-time. (It is an important question why.)

I just now removed a Tiffen 812 filter from its housing. No edge seal on the sandwich. Not even black paint (but it's a flare bomb anyhow). Lack of seal indicates that the Tiffen colorant, whatever it is, is non-hygroscopic. It could itself be an optical epoxy that has been dyed (but with that construction color uniformity would be hard to conrol). Kodak used to sandwich some of their gelatin filters between glasses. Gelatin is extremely hygroscopic. As I recall, Kodak made the glasses a bit larger than the gelatin in order to have a margin with the (non-hygroscopic) cement. One wouldn't dare to cut those filters.

Sorry my earlier response omitted to comment on your idea of artistic work that "expresses or transforms time". I myself am wrestling with explicating "representing time" for a paper I'm supposed to write. Expressing and transforming time are yet more complicated ideas. When the mobile moves it is not just occupying time. This simple use of time, without representation (or expression or transformation) of time, is what makes the mobile temporal art. The ground-level distinction between moving art and static art is not trivial. Time isn't just another dimension. Work that uses time then has access to the higher-level themes "about time" that interest you (and me), but be careful because those themes might be illusory.

Carl, the mobile, by its very name, is moving sculpture. It changes spatial form through time. Indeed the gallery only thinks: "how much space does the mobile occupy?", since the gallery could put other works in its place. The whole gallery, over the course of a year, is a big mobile with its spatial things moving from place to place. But this doesn't make the mobile a spatial more than a temporal thing. Even if you could figure out from a hologram -- a purely spatial image -- of a mobile how it moves, you can't experience its motion as necessary for grasping the mobile.The higher count of its spatial dimensions (3) vs. its temporal (1) doesn't gives the spatial more weight than the temporal for the mobile. The mobile is exhibited motion. Motion is just one kind of change: spatial change. Music is changing sound. Music, at least music made for one ear, is a non-spatial temporal medium. Sound, physically, is temporal without any changing. But I'd argue that a single constant sound, for a duration, isn't music. We really must make a distinction between duration and time. A temporal art involves changes of form/color/sound/pressure/etc. in time. The null change -- the empty gate projection or Cage's silence -- is a silly singularity where temporal art meets durational art. Durational art concerns the observer and the work. If a movie is playing on a gallery wall as people come and go it is not functioning as durational art. Interactive video, a tricky case, is probably not durational art. In durational art, the durations, not just the changes, are the objects of contemplation. The durations can only be experienced when the observer's time is locked to the work's time. Although a physicist can easily derive one from the other, temporality and duration are psychologically and aesthetically distinct. The mind experiences temporality by means of change. The mind can't just add a lot of changes to experience a duration. Duration is experienced its own way. Literature is neither a temporal art nor a durational art. Nor comic books, nor Guernica. The interesting question is whether durational art is a subset of temporal art. I don't think so.

Gregg, today Schneider sells the B+W line of solid glass filters. I don't know if they bought B+W or just partner with them. Your mention of sealant around the edge could be relevant to the discussion. If a laminated filter has edge-seal, then there had better be sealant reapplied after cutting the filter down.

I don't know of any current manufacturer of filters except for Tiffen using that construction. It makes sense when a spectral curve is achievable with dyes in gelatin (or plastic or whatever Tiffen packs in there), but not achievable with in colored glass. Which filters are those? On the other hand some spectral curves are only achievable in glass. Which filters are those? Solid glass filters are far superior optically. For one thing, Tiffen filters lack anti-reflection coating. Tiffen offers this gibberish justification: They concede that coated filters can cut down lens flare but reply that the lens shade can also do it. This misses the point that coated filter + lens shade assures lower flare than uncoated filter + lens shade. Their final sentence commits the same fallacy. Work it out. The uncoated Tiffen filters have about 4.2% reflectance on both sides. These two reflectors can exceed the total of all the reflective surfaces within a complex lens. Lens flare and glosts is caused by one surface somewhere in the lens reflecting the light back toward the scene and then another surface forward of that surface sending it back toward the film. The Tiffen front surface can play the second part, and the Tiffen rear surface can play either the first or second part in a flare contributing scenario. With a high quality lens having 10 air-to-glass surfaces, all multicoated to have 0.4% reflectance, adding the Tiffen filter will multiply the lens flare 8×. With a cheapo lens having 6 air-to-glass surfaces, all MgF2 coated to have 2% reflectance, adding the Tiffen filter will multiply the lens flare 3×. This quick analysis has ignored diffuse reflections within the lens assembly. Here is one independent tester who, whether they realized it or not, failed the Tiffen filter on account of its being uncoated: http://www.lenstip.com/113.24-article-UV_filters_test_Tiffen_72mm_UV.html Uncoated filters suit macho film crews who can wipe 'em on their sleeves. In general, thicker optical glass can be ground and polished flatter than thinner optical glass. So unless the Tiffen filters are twice as thick (and heavy) as competitor's filters, or ground and polished with special effort, they are of inferior optical surface quality to the competitors. This can be measured with an interferometer. Someone should. Tiffen's uncoated, sandwich type filters have a cult following, especially by US cinematographers. Why?

Carl: all good points, but you must clarify how "time-based art" differs from other time-incorporating arts. Your example of 4D art, a mobile, is as much in time as in space. There's no more reason to call it "space-based" than "time-based". It occupies its small space and rolls on in time for hours or years. Its observers approach it from different angles and stay with it for different whiles. If it's a robotic mobile it might wander about town and find its observers as much as they find it. It's as temporal as we are. I think your concept "time-based art" means durational art, in which there's a temporal lock between the observer and the work. The work is some kind of performance or event that has a definite duration. The observer is expected to observe it through that duration. That's supposed to be a requirement for understanding or appreciating it. Sitting in the darkened movie theater for the duration of the movie is an example, called "watching the movie". The precursors are drama and music. They all require that you experience 10 seconds of this, 10 seconds of that, in the correct order. The observer's time must flow with the works. I think this is an extreme idealization which seldom occurs. One might not leave the seat but who doesn't space out during a movie or a play or a musical performance? Who in here doesn't puzzle over how certain shots were made? Who doesn't analyze the work, and think about other works, while absorbing it? This besides thinking about your dog, your stomach, or whatnot. Many, or most, qualities of the work pass through these lapses, but the durational qualities must suffer. The temporal simplicity or complexity of the work gets through without the time itself. I think durational art is overrated. Long-form cinema and short-form cinema will differ in how they fill their time, not the observer's, because the observer's time is always his own. They differ the way novels and short stories, which are not durational arts, differ. The original movies were quickies, viewed not very differently from the 4D mobiles. The evolution from amusing peep-shows to the durational art of cinema was not from aesthetic predestination. The practical/commercial wish to show movies to many people at once required projection. Projection required dark rooms. Dark rooms required people sitting and staying seated. Comes duration, if observers can really do it. Movies' growth to lengths where they could tell complex stories was a wonderful development, because many stories can only be told pictorially. Movies extended literature. But how much of this ability of movies relies on its being durational art? Wouldn't it work as well without the dark room and with each observer's finger on his own media control keys. That is, can't movies which seek to extend literature just behave like pictorial literature: no temporal lock between observer and work. Indeed, you should go to the dictionary occasionally while reading. The purpose of watching the movie is to take it in, in your time, not to have it piped into you. The temporal qualities of a movie -- the kinds of movement, the texture of the time flow -- are separate from duration. They correspond to the temporal qualities of the mobile, but are different because the medium is different. This does not make the 30 second movie, or the movie broken into small episodes by rude viewing manners a space-based art. Non-durational art may be primarily temporal. It may even be completely temporal with no spatial aspects. With further evolution, cinema will finally achieve freedom of shape with no real loss to its temporal qualities. The nice part of the pictorial aesthetic that rests on viewing being in darkened spaces will unfortunately perish.

With deep sympathy for math-phobic cinematographers, this is a discussion about frame shapes, with several posters throwing in the "golden ratio" 1.61803... and Carl Looper getting heavy into numerology. Bill DiPietra declared that Kubrick drew "a perfect triangle" around the ape in "2001" and now ... Please, if the triangle isn't perfect geometrically how is it perfect? Are we having logical discussion or banging bones in here? I now suspect that Bill meant "perfectly symmetrical triangle" when he wrote "perfect triangle". That's normal imprecision for a chat room, especially one that doesn't allow edits 5 minutes after we post. If so his meaning was mathematical, sorry to say.