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Carl Looper

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Everything posted by Carl Looper

  1. In terms of weave, 16mm film is edge aligned in the camera. Not perf aligned. So any scanners that align 16mm film, using the perfs for registration, will exhibit weave, due to a certain amount of weave in the film stock perfs (relative to the edge of the film). Carl
  2. In an oscillation between the left side spring guide and the right side spring guide (were it not otherwise moved out of the way), the right side has more give, so the film would align to the left side guide, and between the left side guide and the right side hard points, the film would end up aligned to the right side hard points (because the left side has more give than the right side hard points) This makes the right side spring guide appear somewhat redundant. But perhaps it's for film that isn't as wide as it should be. At least it will aligned to the left edge guide. Carl
  3. Hi Jeremy, I've acquired the same camera and am having the same conundrum regarding the motor. Would you be willing to share your solution? I'm interested in driving the 1:1 shaft with a custom built motor, but the shaft resists forward rotation and any backward rotation force I apply winds up the spring motor. I'm assuming there must be a way of disengaging the spring motor mechanism but I can't see any obvious way of doing that. Any clues you have would be greatly appreciated.
  4. In the older Ektachrome they diverged at dmax, but that may not necessarily be the case for the newer Ektachrome. The curves may very well be correctly drawn. If they are not correctly drawn that would be a very different issue from the typo identified (log10 units vs camera stops) as it would require someone deliberately drawing those incorrect curves.
  5. Correction. In my last post I said: Since unwanted transmissions through impure dyes decrease with an increase in dye density, you could increase the density of the impure dyes with respect to what you might otherwise do were the dyes pure - or what amounts to doing the same thing: decrease the density of the purer dyes with respect to the impurest one. It should read: Since unwanted transmissions through impure dyes increase with an increase in dye density, you want to decrease the density of the impure dyes with respect to what you might otherwise do were the dyes pure - or what amounts to doing the same thing: increase the density of the purer dyes with respect to the impurest one.
  6. I believe the difference in the RGB sensitivity is to compensate for dye impurity. Reversal film can't use the orange mask method used by colour neg, but it can compensate for dye impurities through control of RGB sensitivity. Since unwanted transmissions through impure dyes decrease with an increase in dye density, you could increase the density of the impure dyes with respect to what you might otherwise do were the dyes pure - or what amounts to doing the same thing: decrease the density of the purer dyes with respect to the impurest one. Cyan is the worst offender, and yellow the least, with magenta in between. The density compensation (of yellow and magenta to match cyan) is controlled by decreasing the blue sensitivity and to a lesser extent the green sensitivity of the film, leaving red exposure (cyan density) as a reference. The result is not as good as the neg/print method, but it would be the best achievable given the reversal method.
  7. The curve provides a map between the amount of light exposing the film (horizontal axis) and the corresponding density of the processed film (vertical axis). We can say from the graph that the new Ektachrome has a dynamic range of about 9 stops. The density range of the processed film is 10.7 stops (3.22 in log10 units). The density range is larger than the exposure range to accommodate for darkness adaption in a cinema environment.
  8. The published characteristic curve for Ektachrome 7294 must have a typo. According to the published curve, the film has an input range of only 2-3 camera stops! That can't be right. Previous releases of Ektachrome have had an input range of about 8 stops. However, if we otherwise assume the input scale on the current publication is in log10 units (the "camera stops" title being a typo), the input range would then be 8 stops, (ie. consistent with previous Ektachrome). Previous curves for Ektachrome have had a larger difference in densities at the shoulder. Can we trust the current published curves?
  9. Yes, that's the implication being drawn. Not that I'm entirely satisfied with the analogy as photography, be it digital or analog, will differ from painting far more than they will differ from each other.
  10. With the invention of photography in the 1800s, the market for particular types of paintings (such as landscape and portraiture) moved across into photography. For a little while there was a sense in which "painting was dead" but it was only a particular type of painting that had died: that type of painting which had been dreaming of photography, anticipating it, mimicking it, faking it, in advance of it's invention. A different type of painting would wake up from it's centuries old dream of photography, to pursue alternative visions of what could be done in paint - and that which photography couldn't do (or could only do badly). And photography, for it's part, would pursue what it could do - not just fake paintings. C
  11. In the previous post I suggested that connecting the terminals 1 and 8, opens the shutter, and disconnecting them closes the shutter, however it might be the case (it's been a while since I've done this) that you need to make a connection followed by a disconnection to open the shutter, and then make another connection followed by a disconnection, to close the shutter. Testing with some ad-hoc probes will establish what is required. C
  12. Depending on what you're after you might find it interesting to make your own control unit for the Leicina, allowing (for example) laptop control of the camera. This can be done using an Arduino as an intermediary between camera and laptop. Or one might use a Raspberry Pi. In any case, for control of exposure time, terminals 1 and 8, in the following diagram, do the trick. You connect these terminals to open the shutter, and then disconnect them to close the shutter. You can test this out using ad hoc probes plugged into terminals 1 and 8 on the camera port. Having satisfied yourself this works, you can then wire these terminals to a relay (be it mechanical or solid state), and switch the relay with a micro-controller (such as the Arduino). The Arduino is very easy to program and can provide an accurately timed delay between connection and disconnection of the terminals.
  13. A flashback need not be from the point of view of anyone. It's not as if the past can only exist as someone's personal recollection of it. If we are free (as we are) to move the camera around in space, and adopt points of view that do not belong to anyone in the story, we're also free to move around in time in the same way. To see more than what the characters can see. Or see less. In both space and time. The film itself becomes it's own character with it's own reasons for being at a particular place and time. I recall a great film (but can't recall the name or the director) in which two lovers agree to meet at some cafe on a given date. When the day arrives, we're there at the cafe, the photography establishing the scene. We watch people walking by. Nothing in particular is happening. Some birds on a telegraph pole. People arriving home from work returning to their apartments. But the lovers never arrive. The film ends on this note. C
  14. Am looking forward to seeing the new print. It's playing at our local cinema in 70mm. Have seen this film so many times over the decades. It was one of the first films I ever saw, which might account for my obsession. But then Chitty Chitty Bang Bang was also one of the first films I ever saw and have had no compunction whatsoever to revisit that film at all. C
  15. Yes, I'd agree that by "film look" Yedlin is referencing normally processed 35mm colour neg. But on the digital side he's arguing against any notion of normal processing, ie. arguing that there is no such thing as a "normal" process, or if there were argued such a thing, he would argue against such a conception, and on that basis he would use a particular process (ie. his particular algorithms and workflow) to obtain the particular look he is pursuing - namely the look of "normally" processed film. This can be read in the following exchange between Carvahal and Yedlin, regarding the test ( http://www.yedlin.net/160105_edit.html ): Carvahal: I'm equally weary of arguments that sound superstitious and find that people in the community frequently obsess more about tools than meaning. That being said I sometimes wonder if our brain is able to discern, even on an unconscious level, the difference between the formats. My point being that the difference is not one of resolution, color or technical artifacts, but one of real vs simulated. Yedlin: This last statement is loaded with quite a few implied premises. First off, it presumes that all of film is one monolithic “format” and all of digital is another single monolithic thing. But this is contrary to the truth, which is that each of these (film and digital) is a mere substrate for an image and is also one small step in a long chain of processes that make the thing you’re calling “format" (I mean, you’re not even differentiating between scanned film and traditionally-printed film, which would be two entirely different things if the premise itself — that capturing an image digitally is fundamentally different — is true). Here we see Yedlin argues (quite correctly in my opinion) that film and digital are not monolithic formats - that the terms "film" and "digital" refer to only "one small step in a long chain of processes" that make up a "format". But yet, in his comparison test between film and digital, film will be processed "normally" (we might even say it's processed according to a "monolithic" conception of film) whereas digital will be processed in any way that satisfies what he's after (such as emulating normally processed film). To put it another way, the various potential looks that might be achieved in film (by different process chains) will be ignored, whereas the various options available in a digital process chain will not. Indeed Yedlin will champion a particularly idiosyncratic digital process. The difference between film and digital exists, and despite what Yedlin might hope to argue, such differences can be both exploited as much as they can be suppressed. And of those who exploit the difference, or otherwise appreciate the difference, they are not necessarily "religious" or "superstitious". Creating a work (or a test) in which the differences are minimised doesn't make us (who might otherwise appreciate the difference) any more aware of why we might appreciate the difference. It just makes us feel as if we should consider ourselves stupid. C ​
  16. The only real problem with Yedlin's test is the assumption that the question being asked, in a film/digital debate, is a question regarding which medium to use. In the case of filmmakers who already use film, (or already use digital), or already use both, the question can be entirely different. For example, if using digital, one might ask "what kind of result can I get that I can't get using film", or reciprocally, if using film: "what kind of result can I get using film that I can't get using digital". In other words one might very well be looking for a way to differentiate between the two mediums, rather than minimise such differences. Yeldin's work is certainly fascinating in that he is using digital processing to get what he calls a "film look". But what does he mean by a "film look"? For elsewhere Yedlin argues that it's not the materials that give you a certain look (as such he calls just raw data) but will be in the way you then prepare such. He will argue that is in the processing of such data ("preparation") that a certain look obtains. Does he mean by this that digital processes provide for such preparation, where film does not? Certainly film is more limited in terms of the processing work that might be done, but it's not as if it is completely absent of such - as if it automagically produces a "film look" (or any other look). In film, one can work towards a particular achievable look, as much as one might pursue some alternative look achievable in digital. And the material/workflow differences between film and digital will not be irrelevant. Demonstrating that one can prepare both film and digital in such a way that they both have the same look (what Yedlin calls a "film look") merely demonstrates that there is a small overlapping domain between the two mediums/processes where such an in-common look can be obtained. C
  17. So here's a graphic visualisation of the logic I'm using. For any shutter orientation (left column) can be found (at some other time) a shutter orientation (right column) which exactly counter balances the exposure given by the orientation in the left column. But if both edges of the shutter occupy the frame at the same time (third row), there is no such counter balance to be found (at any other time). This motivates an alternative to a radial design.
  18. If the angle of the shutter blades is such that only one blade can intersect the film frame at any given moment, then a radial design seems to me optimum. For any given moment in which one blade splits the frame in two (between shadow and exposed), one can find a reciprocal moment in which the other blade has divided the frame in the exact opposite way. It would only be when both blades are intersecting the film frame at the same time, that they can no longer act as the inverse mask of each other. C
  19. Ok, I've worked out the reason for the diagonal design. It's for when the shutter angle is being made smaller (towards closed). For a fully opened shutter (130 degrees) a radial design would be appropriate (and optimum), but for a shutter approaching closed (smaller angle) it will reach a certain angle where both blade edges are shadowing the film at the same time. If a radial design were maintained, areas of the film further from the centre of rotation would receive more light than areas closer to the centre of rotation (for the duration of the exposure). The diagonal design (or a high order curve design) would act to compensate for such. C
  20. Hi Simon, I'm going to suggest that the reason there is a difference in exposure between one side of the frame and the other, on film exposed with a variable shutter Bolex camera, (as small as this difference might be) is due to the variable blade (for whatever reason) being other than along a radial line. In other words, I'd suggest the diagonal design isn't solving any problem to do with exposure time, but creating one in the first place. At least that's the current conclusion I've reached trying to model (understand) the situation. I am, of course, open to correction on this. C
  21. I understand the distortions that can occur with shutters exposing a dynamic scene, since each location of the film is being exposed at a different time. But I've yet to correctly understand why a radial shutter design (exposing an otherwise static scene) would experience a difference in exposure time across the frame. When I try to model it using a circle pattern at the shutter plane (based on a wave model) I'm still getting an even exposure across the frame. I take it as correct that there is a difference (motivating high order curve designs), but am having trouble modelling it. C
  22. With negative film such as Vision3 50 D, being out by one stop from an ideal exposure, isn't going to matter very much at all. The stock has such wide latitude I imagine you could be out by two stops and it would still look brilliant. It's with reversal film stock that a tradition of fussiness emerges (aiming to be within one third of a stop to the ideal exposure) because reversal stock has limited latitude and so is much more difficult to correct in post. Indeed, traditionally, there is no "correct in post" as the camera original is shown, as is, in the projector! Of more importance (as a rule) is consistency (whether exposing negative or reversal). Between shots that are meant to look the same (same location, same light) it's of more importance that the shots use the same exposure, ie. regardless of whether they are "correct" exposures. There are, of course, exceptions to this rule. C
  23. Everyone has to live in the world we've created (or otherwise found ourselves in) no matter what we do, be it art, engineering, science, entertainment, business management, living off the grid, or whatever. C
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