Friedemann Wachsmuth
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Aapo, it sometimes feels like you are over-complicating things a little 🙂 Generating almost any custom frequency with crystal precision is about 10 lines of Code on any Arduino, no extra hardware needed for dividing. Just make sure your Arduino uses a crystal, not a resonator, many cheap clones use the latter, which is less precise. Also, I don't think there is a need for phase and frequency measurement. Just count and compare the pulses from both sources. The diff is the input for your motor driver. Done.
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Why external counters? You should just use the Atmega/Attiny Timers. They are crystal acurate and give you almost any frequency directly without extra hardware. This gives you exactly 25 Hz on a 16 MHz 328p: // TIMER 1 for interrupt frequency 25 Hz: cli(); // stop interrupts TCCR1A = 0; // set entire TCCR1A register to 0 TCCR1B = 0; // same for TCCR1B TCNT1 = 0; // initialize counter value to 0 // set compare match register for 25 Hz increments OCR1A = 9999; // = 16000000 / (64 * 25) - 1 (must be <65536) // turn on CTC mode TCCR1B |= (1 << WGM12); // Set CS12, CS11 and CS10 bits for 64 prescaler TCCR1B |= (0 << CS12) | (1 << CS11) | (1 << CS10); // enable timer compare interrupt TIMSK1 |= (1 << OCIE1A); sei(); // allow interrupts ISR(TIMER1_COMPA_vect) { // Anything written here is called 25 times per second // once the above got executed } Here is a good primer, but there are many others too. Oh, and for 24 fps, you should create a 264 Hz timer and divide by 11 for the closest match. You get 264.000264000264... Hz with OCR1A = 60605 TCCR1B |= (1 << CS10); // Prescaler 1 which, divide by 11, gives you 24.000024.. Hz — that's more accurate than any crystal is.
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No, I am not really interested in building a scanner. I am building an open source DC motor control for projectors, cameras, viewers etc, which costs a few $ only and needs barely anything else than impulses to run 100% locked at crystal speed. It doesn't care about altering friction or differing torques, it is always precise, not needing any adjustments — just control impulses from the motor or any other directly driven part.
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Well, good luck then! 🙂
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The current code and pcb design is at https://github.com/fwachsmuth/ErnoCCC — very dirty still and barely documented though. The way it basically works: A Timer ISR increments a counter as reference pulse. The shaft impulses (optical here) are wired to Interrupt pins too, using quadrature encoding — their ISR increments another counter. The loop compares the counters and uses the delta to impact the motor current — that's it. In my example, there is also a freq measure capability using ICP1 on PB0, this is only used when the motor gets manually controlled (to show how fast it is currently running). To derive the motor current, I use a DAC (12 bit) and feed its output into an R2R opamp, which generates the high impedance signal for the existing motor controller. There is also a calibration routine which iterates over voltages to find the current for two reference speeds, creating the math for any intermediate frequency needed. This is necessary since friction in all viewers differ, based on condition of the belts, bearings and lubrications etc. Hope this helps!
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Here is an earlier prototype in action. The top line of the display shows the current frame count, the second row a SMPTE timecode. The button underneath cycles through 9, 16 2/3, 18, 24 and 25 fps — this affects the time code calculation on the one hand, the motor speed control on the other hand.
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Interesting Thread! Aapo, I am also working on a universal, crystal based DC motor controller. Mine is also 328p-based, but using impulses from the motor shaft to maintain speed. So independent from torque, speed is maintained with crystal accuracy. My current board is designed to be a replacement for Erno Motor viewers, but the concept is universal. I am also controlling Bauer and Braun Projectors already with this, using their organic impulses and "hooking up" to their existing controller, not replacing it. Contrilljj in mag any external camera motor would be trivial too, all I need is some impulses coming from the motor shaft or claw or so. I am also not afraid of PCB-CAD nor SMT-soldering. Also, you nowadays can order very small SMTA batches from China for little money. My code and w hematite are totally open source, so I'd be glad to join forces :) Here for example are the boards I just got on Friday, designed to fit into the motor viewer. Note the segment disc that gets mounted on the sprocket wheel shaft and never loses a single frame impulse. :)
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Bray E-Series Manual
Friedemann Wachsmuth replied to Friedemann Wachsmuth's topic in Film Stocks & Processing
Hey John, I am not sure about the config, the previous owner die C-41, E6 and bw-neg with it. He also offered me with help and answered my initial bunch of questions :) One Q: Is there any way to do the re-exposure for bw-reversal inside the Bray, not chemically but with light? My Bray has a kind of "gate" after the third tank, that suggests to allow a lightsource behind it, but I would not know where and how. I had been in contact with a Ruth Marsden at Bray Plastics, and just got a "I have asked the question and we have no manuals or paperwork in relation to the E-Series processors, we discontinued production approximately 10-14years ago and all relevant paperwork manuals etc. sorry we could not be of help." Weird. I still need to get tempered supply water and a drainer box installed at the place where I want the Bray to operate, so haven't even turned it on yet. Oh, one more Q: The previous owner used the 70mm leader and pulled up to four S8 films through it in parallel. Have you tried this too? Or even more films? -
Hey, I recently got hold of a Bray E-Series in working order. What a great little machine! I haven't fired it up yet, but it was in use until recently and is in really good shape, including spare parts. The only thing missing is the manual. Does anybody here have the manual and could scan it for me? I got the Manual of a Bray Magitrak, but it's not the same. I also contacted Bray Plastics in the UK (which is their name now), they claim to have no records, plans, schematics or anything about the E-Series anymore. Would appreciate any help! F
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A new development tank?
Friedemann Wachsmuth replied to Friedemann Wachsmuth's topic in Film Stocks & Processing
Thats all good feedback. Keep the wishes and needs coming :) -
For those of you who are on facebook, please join this poll. For those of oyu who are not, feel free to comment away here -- unfortunately, cinematography.com does not seem to have a poll option :( ------------------------- Just imagine, hypothetically, that there would be a new development tank on the market, designed for 8mm and 16mm films of 50 or 100ft length. It wouldn't be a radically new design, mostly following the design of the common Lomo tank, but it would be manufactured with much higher precision based on modern, durable and stable plastics slightly bigger to also take films that are a tad longer than 50/100ft easy to load without hassle easier and faster to be filled/drained more efficient during washing compatible with all known and unknown processes manufactured in the EU, with spare parts easily available (maybe) extensible, so allowing larger stacks than two spirals (maybe) providing a tank option with built-in temperature control (maybe) providing a built-in timer that helps with process timing Would you ne interested in buying such a thing? And what would be the most important options for you? [ ] I'd pay $300 since that sounds a lot better than the Lomo option [ ] I'd pay $500 since I know this is hard to manufacture [ ] I'd really want the option of larger spiral stacks [ ] I'd pay even more for the full setup, especially if it really becomes a modular system [ ] I'd really want the built-in temperature control [ ] I'd really want the the built-in process timer [ ] I absolutely want the ability to develop 100' in one strand without cutting it in half [ ] other: _____________
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I love it. And see no scratch..?
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Make sure to watch this in highest quality and fullscreen: https://youtu.be/3Nh9BTMWj9M Or better download this version and watch it offline: https://drive.google.com/file/d/0B9PJ3Kp3qOe4UklQZ0NrM1dNaVk/view?usp=sharing If anybody interested, I can also share an ungraded ProRes 4444 snippet. All the tripod shots where shot with the Optivaron (recognisable by the slight vignette in top right, since I did not take the lens hood off). All handheld shots (mostly in the middle) were taken with the Fujinon lens. The incredible folks from http://www.gammaraydigital.com/did the scanning, once in 2K and once in 4K. Unfortunately, my Mac Pro (late 2008) is a bit too old to handle 4K video, so I had to grade the 2K version. It still looks amazing though, make sure to download the 2K version for full quality! The clip was stabilized (tracking marker put on the frameline) since the scanner software used currently does not register based on the +2 sprocket hole, but on the sprocket hole next to the visible frame. You can see how bad the sprockets in this cartridge were if you watch the weaving sprocket hole on the left. But watch how image and frameline are like welded together: Absolutely no jitter, weaving and a sharpnes I have never seen before with any other Super 8 camera. This is due to the registration pin -- so thanks to Denmark for finally making a S8 camera that has this professional feature! If you don't have a Logmar yet, order one now. I tell you, the achievable quality is abso**(obscenity removed)**inlutely addictive. :)
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There is absolutely no space for this I think. Remember there is the claw and the registration pin already, beside the pressure plate. Both pins support high torque and operate with extreme precision, so their gudance is pretty solid. Also, there is the mirror system with the beam splitter closeby too... However, since the claw is at the -2 position (ISO 1787-1984) like in any projector, actual registration pitch variance should not matter. This is als long as the scanner used uses the same sprocket hole for vertical registration (the LaserGraphics Scanstation does not). You are right Carl, horizontal registration is provided by film guides (with two spring loaded saddles to cover slitting tolerances). Below attached is a photo of a beta-version of the claw/registration module. (This has still 3D-printed parts and differs from the final design which required changes to make film loading easier) Meta data can be logged by the software onto the SD card, actually even as Excel file containing all settings, takes and timecodes. :)
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I just made some good progress with modifying E6 to give better results when processing VNF films: http://www.filmkorn.org/e6-fuer-ektachrome-vnf-filme-optimieren/ Let me know if you need an english translation. Bottom line: Add 3.5ml Benzyl Alcohol per Liter of working solution to the Color Developer. Stirr 10 minutes very well to dissolve this oily additive. You get way better Dmax and more saturated colors!
