Dennis Couzin

Following onto Tyler Clark's suggestion. Get a 1 RPM synchronous motor. It's speed is exactly determined by the AC frequency, nominally 60Hz. Feed it 75 Hz instead. You can make that exact AC as an audio signal and transform to the needed voltage. So, no need for gearings or tachometers, just an accurate audio oscillator.

This concerns the ACES IDTs for Canon EOS C300. I suspect that the 3x19 matrix and the whole Canon color science is nonsense. If there are others who know color science and wish to discuss this, contact me.

I miscounted. "first three responders" should be "first four responders". I meant to include myself, since I also responded in terms of film and I do find that funny. The topic was how to project 120+ images per second. How to get the light out there, to shine images onto "dancers, blowing smoke, shattering ice, flowing fabric, etc." as Refah later revealed. It's an engineering question far from the nature of photographic imagery versus video imagery. Video projectors can shine images onto things, so we should have thought of using them. David was the first to. Full disclosure: I devoted 16 years to film, then despaired over its future and left image making altogether for 13 years, then took up video (9 years ago). I thought I'd made the transition from film to video, but I answered in this strand in terms of film because sprockets and genevas are so cute. You never can forget them. But cute does not imply profound and cute can even become dreary. We need to honestly ask what was irreplaceably special about film. My hunch is that it was not so much the film and equipment as the technological culture surrounding it. Film developed in a whirl of invention and science. Video is developing in the grip of engineers.

For FCP7 there is LUT Buddy, still free from Red Giant. LUT Buddy doesn't like all formats. I have had success with it for 17^3 and 31^3 LUTs in .mga format. You must find out how it does with your LUTs. Since all LUTs are text files you can transform one format to another in, say, Excel if you know what you're doing. If you really know what you're doing, you can construct your own LUTs.

Dom is certainly correct that the black painted scratch poses a danger of being in focus! It's a depth-of-field problem to decide if the plane of the front surface of the lens is sufficiently out of focus. It's not focal length per se that determines this. For example, if the 50 mm lens has its entrance pupil at the lens front surface the black line on the front is totally out of focus and has no optical effect at all. So the seldom mentioned lens dimension "entrance pupil depth", E, needs to be reckoned in the danger equation. When a lens is focused far, the blur circle from an object at the front surface has diameter f*f/N/E. In the numerator twice, f is the focal length; decreasing it tightens the blur circle. In the denominator, N is the f-number; decreasing it enlarges the blur circle. Also in the denominator, E is the entrance pupil depth; decreasing it enlarges the blur circle. For the black painted scratch to have no optical effect at all, f*f/N/E must be as large as the film format. For film format 12 mm, f = 50 mm, N=16, E is then required to be less than 13 mm. You don't find many 50 mm lenses with such shallow entrance pupils, confirming Dom's point. A very narrow black line requires less blur to make it effectively invisible. This is too much trouble to calculate. Better to test empirically by wiggling a black thread on the lens front surface with the lens at its smallest aperture. However when the wiggled black thread is found to be visible, a wiggled white thread will also be visible. The unpainted scratch is like a light grey thread. It is a light scatterer, not a refractor, because it is rough. About half the lightfall at the front surface, from all directions is scattered forward by the scratch. If this were completely out of focus, as in the earlier discussion of "cleaning marks", it would contribute veiling glare, but it can be somewhat in focus according to the f*f/N/E blur circle formula. A scratch that would make trouble blacked-in probably makes trouble not blacked-in.

Your tolerance for dust, like tolerance for scratches, should depend on your tolerance for flare (veiling glare). Dust scatters light so the darkest, or most color saturated, parts of the image are veiled with the rest of the image. The classical test for lens flare is to photograph an extremely black spot (black velvet or better a light trap) against a white background. Modern multicoated lenses have less than 1% "flare factor" meaning that the utra black spot exposes the film less than 1% as much as the background does. Dust adds to the flare factor according to how much of the surface is occupied by the dust. It is common to over-estimate that area, but if dust really covers 1% of the surface I think it will add about 0.5% to flare factor, which should be intolerable to users of modern multicoated lenses. So-called "light cleaning marks" are the most offensive flare sources. They too operate as scatter sources and they can easily occupy 1% of the surface. Clean-clean-clean. Single deep scratches are much less offensive because they occupy much less of the surface. An isolated scratch on a lens can be painted-in black and then have no optical effect at all. The cinematography establishment in the US was slow to appreciate low-flare optics. Even in 1980 it had proponents of uncoated glass filters vs. coated ones, the former being more durable!

Thanks to Simon for finding US patent 1921835, applied for in 1929. It is for a continuous optical printer which can blow up or reduce with the two films kept perfect synch since the large and small sprockets are cut into the same wheel. The patent text at page 1 line 20 says: "it has long been a problem in connection with continuous projection printers ..." so the 1929 invention wasn't the first of these, just an improvement. Step optical printers are much older. Any lab with a camera and a projector could do step optical printing. Even before small gauge films existed, portions of the 35 frame were being blown up to the full 35 frame with these. Continuous optical printing has a speed advantage over step optical printing. It made optical release printing economical. (Also it could handle the optical sound track, which step optical printing couldn't). The step optical printer could always make a less economical (silent) release print or it could make a printing negative. So I'd guess the answer to Jean-Louis' question is: as soon as there was 16 mm film.

David Mullen's suggestion is the practical way to go. It's funny that the topic starter and the first three responders thought only in terms of film. For extremely high speed recording, video cameras can now surpass the Fastax's 10,000 fps. However, the Fastax technique of a rotating prism is equally applicable for camera and projector. With video, recording and projection are two completely different technologies, and there are not ultrafast video projectors, so far as I know. Even the sought 240 fps might be impossible today. Extremely fast video projection should be possible with a DLP chip by sacrificing tonality and color: one-bit video. That is probably not the effect Refah wants.

To recapitulate: One way to film the 240 fps projection at 240 fps is with a 240 fps intermittant motion projector and a 240 intermittant camera. They are just barely mechanically possible. Not just the mechanism but the film perfs must withstand the accelerations. Wheeler estimates the maximum fps for the film at 300 fps. He wrote pre-polyester based film, but while the poly might not tear it might deform. If you can find a 240 fps intermittant camera you can probably buy a second one to convert to a projector. The second way is with a 240 fps projector that uses continuous film motion with optical intermittancy. This is the rotating prism projector, e.g. the Steenbeck movement suggested by Simon Wyss. The image quality is poor. You must also find a 240 fps camera. The third way is with a 240 fps projector that uses continuous film motion so the image streams up the screen, but a strobe light to freeze it in midframe every frame. Building a good projector of that kind isn't easy. If you start with a basic sproket-loop-claw-loop-sprocket projector, and remove the claw mechanism while installing a roller to keep the bottom loop it can run very fast. But the streaming isn't well governed. Those drive sprockets aren't cut precisely and also gate pressure will introduce perturbations. You're better off using the continuous film transport system from a film scanner of that type. Some are even stroboscopic but you'd need a much stronger strobe

Oops again, although this won't change much. The slit might be travelling about four times -- it depends on the shutter's cut-off angle -- the speed of the flowing image. Still big blur.

Oops! My analysis of the shutter requirement was wrong. The 0.43 degree slit would be travelling in an ordinary camera shutter so it would move at only about twice the speed of the flowing image: hence big blur. If you could set up the camera so its shutter travelled horizontally while the projection flowed vertically, or vice versa, then you could get sharp, but badly sheared, images from the slit shutter. Go strobe.

Expecting the 240 fps camera shutter to freeze the 240 fps non-intermittant projection fails for two reasons. 1. In my example, you need a strobe flash of about 10 microseconds to sufficiently freeze a 120 fps flow, so 5 microseconds for your 240 fps flow. That's a 0.43 degree shutter. You'd have to fabricate such a camera shutter and then ... 2. The exposure will be insufficient under any practical continuous lighting with the 0.43 degree shutter. Strobe makes the special shutter unnecessary and provides the necessary exposure.

It's a nice video, best watched in HD. The large chromatic aberrations show that it was done with a prism filter. Part of the dreamy effect Craig might be liking is due to that chromatic aberration. That exact look will be difficult-to-impossible to emulate in post. Color aberration is due to the wavelength-by-wavelength action of the prism. A film picture cannot record the original wavelengths, only the original hues. So, for example, a yellow laser line against a dark background will not make color fringes though the prism. But in the film picture, the laser's yellow is 2/3 of the spectrum, green + red, so a post production prism emulator which tries to emulate color aberration, will give the laser line fringes. In short, there's some danger of a post effect that lacks chromatic aberration and is too clean or one with faked-in chromatic aberration that looks so.

@Refah: Do you mean this? Must someone look at the projection and make out fast action, or do you merely wish to get all the information in 120 frames of film onto the screen in 1 second in such a way that at every instant no more than two frames appear? Perhaps describe your application. @others: Another kind of high speed projector moves the film continuously and uses a strobe lamp, very accurately synched to the movement. For 120 fps, a 10 microsecond flash introduces a blur of just 1/833 of the frame height, probably better image quality than a rotating prism system.

Oops! One link in the previous post got an extra "http//". Fixed here: ... the relative spectral sensitivity function for Fomapan 200 is somewhere between this: http://www.mediafire...an200_sf1.3.jpg and this: http://www.mediafire...an200_sf2.0.jpg

As fewer filmstocks are available, we must learn how to adapt to what there is. Three B&W negative films called Fomapan, made by Foma in Czech Republic, may become available in 16 mm cine gauge. Find Foma's data sheet for Fomapan 200 Creative here: http://www.foma.cz/en/fomapan-200 One peculiarity of Fomapan is that its spectral sensitivity is high out to nearly 700 nm. It might be termed "super-panchromatic". There is nothing wrong with having too long spectral sensitivity, since what isn't needed can be filtered out, but the cinematographer will have to learn how to filter the super-panchro film for good pictures. Human vision responds to the different wavelengths according to the photopic luminosity function. Here it is graphed on a logarithmic scale appropriate to photographic sensitometry: http://www.mediafire.com/view/nn2aw8pgl4fmkd6/human.jpg . B&W pictures are visual lightness records when the film's spectral sensitivity function matches the eye's. Comparing the "human" curve with various published panchromatic spectral sensitivity curves shows that all the films are much too sensitive in the blue wavelengths than they should be. That is why many B&W cinematographers routinely employ a yellow filter. The K-2 yellow filter is the most popular. For the red wavelengths the panchro films curves accord decently well with eye's. We unfortunately do not have proper spectral sensitivity curves for the Fomapan films. Foma provides a curve which they call a "spectrogram". Notice that their curve is lacking a scale on its vertical axis. Calling the sensitivity "relative" does not exempt you from having this scale. Since the spectrogram is made with a logarithmic density wedge, the scale will be logarithmic. "Relative" means you don't care where you mark "0" on the vertical scale, but the scale must show how far it is from 0 to 1. Otherwise you don't know how sensitive the film is at one wavelength versus another. Foma would have to provide additional information: range of the neutral density wedge gamma of the film how the curve was picked off the spectrogram (continuous tone image) in order to determine a scale for the vertical axis. Better they just figure out the scale. I played around with Foma's curve and can at least estimate that the relative spectral sensitivity function for Fomapan 200 is somewhere between this: http://www.mediafire.com/view/rj87rj2jo3kfms4/fomapan200_sf1.3.jpg and this: http://www.mediafire.com/view/n4arjj87i5blp21/fomapan200_sf2.0.jpg The main problem with being super-panchromatic is recording red colors as too light. It is the opposite of shooting with orthochromatic film. Imagine a very red thing that reflects all wavelengths past 600 nm. In D65 daylight, the human eye sees it as 15% as light as a white thing. Unfiltered Fomapan sees it as 23% as light as white. But Fomapan with the K-2 filter sees it as 43% as light as white. Therein lies the problem. The excessive red sensitivity in itself does not make reds photograph drastically light, but when the excessive blue sensitivity is corrected the reds photograph fully 1½ stops too light. Color conscious B&W cinematographers will want to find the long wave complement to the K-2 filter to correct a super-panchromatic film such as Fomapan. A strong Kodak CC Cyan-2 filter is in the ballpark, but Kodak has discontinued the Cyan-2, and anyhow gels are not practical for regular use. A Schott KG-3 glass is in the ballpark, but you must find one that has not been tempered as "heat absorber" or it will be optically poor. Perhaps there is a high quality anti-reflection-multi-coated "photographic" filter to roll off the sensitivity past 600 nm. Good hunting.

In the 1980's I and others working in 16 mm optical printing wanted a 16 mm version of Eastman 5369 (High Contrast Panchromatic Film). 7362 was available, but having the panchro hicon film saved one printing step and it was a sharper film. Kodak accepted a special order for (as I recall) 36 400' rolls of 7369. I dealt with pooling the money. I didn't put my label on the rolls. I was happy to not end up with too too many rolls for myself. Kodak was willing to make specially slit and perforated batches of the emulsions on the bases it already made. Kodak still is, but its minimum order is now 420 400' rolls. Foma is willing to make specially slit and perforated batches. Their minimum order might be 68 400' rolls. Mr. Partenie didn't agree to my first recommendation. Why-oh-why must his ego stick on every can of film he resells? Does he want your film credits to say "shot on Valerian's Fresh Film" rather than "shot on Foma film"? He ducked the second part of my second recommendation. I believe he is not in the UK. Does "Director, Wrexham, UK" mean director of a shell company in Wrexham, UK? If the participants in this strand accept Mr. Partenie's way of doing business or are too lazy to do it better what can I say but: he he.

News and Recommendations I have learned from Foma in Czech Republic that a Valerian E Partenie is negotiating with them to resell their Fomapan film cut and perforated 16 mm by them. Why did Mr. Partenie conceal this information from the forum? Why doesn't Mr. Partenie sell the Fomapan film with the Foma label so the buyers know what they are getting? If he plans to later substitute other product, he must be prevented from doing this from the start. Demand that Mr. Partenie drop his absurd "Valerian's Fresh Films" label and resell Foma film as "Foma"! Demand that Mr. Partenie say who he is and where he is! If he refuses, make a different arrangement for redistributing specially slit/perfed Fomapan.

This "veil" reasoning, like your earlier "mask" reasoning, is plain wrong. The emulsion is coated on the grey base. The developed emulsion has a range of densities and the base has a constant density. The film density is the sum of the two. So the film density range is exactly equal to the developed emulsion density range. QED You speak of "brightness range". Probably you mean luminance by "brightness" and you are subtracting the lowest luminance from the highest luminance to measure a luminance range. You should be dividing the highest luminance by the lowest luminance to measure the luminance range, because that ratio is what accords with vision. QED When you say that "the lightest parts of the image appear as ... grey" I imagine you examining the developed film on a light table. Then the lightest parts of the film do appear grey. The grey base is grey! It is grey relative to the white of the light table. Now mask off the white of the light table, even in the film perforations, so the transilluminated film is all you see. The lightest parts of the film now appear white. QED If you examine the whole image under these conditions the contrast is less than it is by projection. This is due to the Callier Effect, not the grey base. A light table transilluminates diffusely and a projector transilluminates more nearly specularly and the Callier Effect for the B&W emulsion is substantial. The diffuse density range is expanded by nearly the Callier factor to the projection density range. So a light table, even well masked, is a poor way to evaluate the tonality of B&W images intended for projection. Grey bases are achieved by dyes so the base is hardly diffusing and doesn't reduce the Callier factor of the film. In all, reversal processed grey-based film is OK for projection. The 0.2 density of the base has the same effect as a ND 0.2 filter on the projector lamp or the projector lens. It should not be necessary to explain this in this forum.

This is a serious error in your thinking. A grey base doesn't mask anything. The white projects 40% darker, the middle grey projects 40% darker, and the black projects 40% darker. If the room is dark and the projector is of normal brightness the eyes adjust to the dimmed image and the grey base has no visible effect. If the room has excessive light sources, like exit lights or incompletely covered windows, the 40% dimming of the projection would compromise the blacks, not the highlights.

I also looked at the M:HQ ratios and found the difference substantial. The question isn't whether D-76 and D-96 can't ever give similar images, but whether they give similar images under like conditions of time, temperature, and agitation. Otherwise the sensitometric data for D-76 is irrelevant to D-96 processing. No on-reel processing can ever give anywhere near the development uniformity of continous strand processing. Developing 120 film "without streaks" doesn't cut if for cine film that will be projected with time substituted for length. Please read my post #66. The cine film requirements are being overlooked. Concerning reversal use of this Formapan negative film, the grey base is not a serious problem. The original will project darker, if one projects the original. I think the gamma is the problem. Tri-X Reversal film has diffuse gamma = 2.0 in its linear section. What reversal first developer can be found to crank Formapan negative's gamma up to 2.0?

1. "Sensitometric tests" per se are not lacking for Valerian's Fresh Films, since the film materials are exactly "FOMAPAN [100/200/400] Creative" and Foma has done sensitometric testing. (A proper log sensitivity vs. wavelength spectral sensitivity curve would be nicer, and also the aperture size must be given for rms granularity.) Those same sensitometric results apply after the film is cut to cine dimensions but they are no longer relevant because... 2. Cine film is seldom developed on small spiral reels with "agitation or turning over continuously during the first 30 seconds, then during the first 10 seconds in every minute". Cine film is generally developed in continuous processing machines with passive or active agitation completely different from that of the Foma testing. So 9 of the 11 graphs -- with Characteristic curves and Development curves -- in each Foma data sheet are irrelevant. Also the standard Kodak developer for laboratory B&W developing is D-96, which is substantially different from Kodak D-76, etc. 3. Who will do the tests of emulsion uniformity and perforation uniformity?

There are two requirements peculiar to cine film stocks that do not apply to still film stocks (like this Fomapan being sold as Valerian's Fresh Film): emulsion uniformity and perforation uniformity. They are omitted from specification sheets (even from Kodak) but are very important parts of the internal quality control for cine film stock manufacturing. Emulsion uniformity. Minute random variations, like D = 0.01, from centimeter to centimeter, make absolutely no difference for a still film stock. But as they translate into frame-to-frame differences in cinema, they make visible flutter. Cinematographers should test the Fomapan versus the Kodak film for uniformity. Shoot a grey card with a camera having a steady shutter. Use the good cine lab. Then either use an accurate densitometer on many consecutive frames or project the films and see. Perforation uniformity. Because camera, printer, projector typically locate a film frame using a different perforation (or perforations or parts of perforations or a film edge) relative to that frame, inaccuracies in perforation translate into image jumpiness. Again, these are not part of a cine film stock's public specification, but in-house standards. For example, in 1989 Kodak announced that it had tightened its perforation tolerances on all its 16 mm film stocks, while giving no numbers. Pray that the cine-perforated Fomapan has as accurate perforations as pre-1989 Kodak cine films. (It is not difficult to test perforation accuracy. One method is to shoot a fixed target twice, using two cameras having disagreeing pin systems, in a double exposure.) If Foma itself is doing the cutting and slitting then it shouldn't be too poor since Foma had experience making 16 mm films in the past. But if some amateur is doing it, beware! In the late 1970's, wanting a high contrast film in double-8 mm, I found a joint that was interpolating the extra perforations into 7302 film stock. It was terrible. There have always been know-nothing buffoons operating at the fringes of motion picture technology. It is an exacting technology, with few shortcuts. Those working to keep 16 mm cinema alive should consider carefully whether the aesthetic properties of 16 mm cinema that matter to them will tolerate the shortcuts meted out to them.

These are Fomapan films. The sensitometric curves are from the Fomapan data sheets. It would have relieved some skeptics here to know that the manufacturer is Foma in Czech Republic. Perhaps Valerian can pay Foma a little extra rent for the Fomapan name. Cinematographers have a right to know where their film comes from. The sensitization might better be termed "super panchromatic" than "panchromatic". Spectral sensitivity to 700 nm is way beyond Eastman 7231. So cinematographers wishing to maintain the Eastman panchro look must find a filter to remove the long wavelength sensitivity. Otherwise expect a surprise! Foma's spectral sensitivity data is primitive compared to Kodak's. It's a "wedge spectrogram". Information is lacking for interpreting its vertical axis. It's logarithmic, but that's not enough. We can't even remove the curve's 2850K bias without knowing the vertical scale. So cinematographers must determine the effects of their filters from scratch.

Yes, the 25 mm f/1.4 C-mount Switar is more or less astigmatism free on a C-mount camera but the prism (functioning just like a 9.5 mm thick glass pane) introduces severe astigmatism when the exit pupil is close. For this particular lens the exit pupil is about even with the flange. RX lenses solve this problem in one of two ways: the RX lens can have exactly the right amount of astigmatism of the opposite sign; or the RX lens can be astigmatic and have its exit pupil far from the image plane. I believe the 25 mm f/1.4 RX Switar worked the first way and the 26 mm f/1.1 RX Switar worked the second way. Incidentally, the very concept of seting the backfocus of a C-mount lens for an RX camera is a confusion. If the C-mount lens is compatible, as many are, the rear focus should be the standard C-mount 0.690". If the C-mount is incompatible, as many are, you can only fudge a little and reduce the aberrational error by resetting the backfocus. It is worth doing with a zoom lens, but with a prime that will be focused by eye, if the reflex focusing works then the fudging will be accomplished there. And you guessed it, there is also a problem with the reflex focusing on the Bolex RX. The path to the film is 9.5 mm of glass while the path to the the groiundglass is 19 mm. This problem affects focusing with every kind of lens. I wrote two articles on RX compatibility. A 1976 one is found at: http://www.city-net.com/~fodder/bolex/truth.html A 1987 one seems to be missing at: http://erictheise.com/films/library/Dennis...n-RX-C-Rule.pdf