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Dominic Alt

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About Dominic Alt

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  1. No offense intended, either to you or Bruce, but that would be my remote diagnosis. In any case, Mitchell or Arri, basically the same thing. Not much torque is required. If the vibration is a problem, try a smaller motor, or less current through the motor. If not, no need to change anything. I've only seen the old motors in pictures. Very impressive. When running at normal speeds, it is nice to have a giant motor for fast acceleration. I'm not sure what size magazines were used with those cameras, but I think 1000' magazines were available. That puts a load on the camera. I just bought a wild Mitchell MKII motor door. The attached motor is 1/6th horsepower! Not football-sized but it is bigger then a soda can. I will be replacing it with a much smaller motor, but for single-frame only. No sync.
  2. Is your scan rig an Arri II or similar? And did he put that whopping big, rare earth, stepper on the 1:1 shaft? If so, that was a big whopping mistake. When you use a stepper, the torque of the motor must be matched to the torque of the load. The 1:1 shaft of an Arri is a light load. Replace the whopping big motor with a smaller motor and you'll be much better off. Maybe it won't pass the penny test, but it might pass the nickel test. :rolleyes: The Nickle/Penny Test
  3. ...or wrap the dead fuse in tin foil. In an emergency, that will work. :rolleyes: For fuses in the USA, try Parts Express
  4. Last question first, yes, you must disengage the motor to manually rotate a Bolex. First question: as to when you'll get flicker, that is unpredictable. Depends on many factors. So... I would recommend shooting a test, especially if you are going to use the variable shutter to cut exposure time. While shooting the test, you can fire off some single-frames with the spring shutter. You get a nice fast shutter speed. If there are no problems in the test, then you can animate with confidence. I actually gave the wrong shutter speed. 3/8 second is the "adapted" shutter speed compensating for the prism. The gearmotor takes ("about") 1 and 1/3 seconds to make a full turn, giving a shutter speed (assuming a 133 degree shutter) of (133/360) * 1.33 = 1/2 second. So the true shutter speed is 1/2 second. Yes, that is very slow!
  5. That's an easy one. It's limited to a single speed, 3/8th second. You never have to worry about what shutter speed is most appropriate! Because you can't change it. Oh, and it's a wild speed. Hopefully, you won't get flicker. As far as just using the single-frame release on the Bolex, that is 1/30th of second, when the I-T knob or lever is in the "I" position.
  6. It's not missing anything, it's a H16 J. Designed for surveillance, back before video was available. No internal motor mechanism. To run it, you'd need an external motor, for example: For $40, it is a good buy. You can sell it on eBay for more then that.
  7. Are you talking about the "loop formers"? If they are working properly, and retract when that 'button' gets pushed down, there is no need to remove them. If they don't retract properly, then you have to fix or remove them. Loading with loop formers: Loading without:
  8. Last time I checked, it was $195. That's only 125 Euros. :rolleyes: In any case, widening the gate is 'free'. $190 is to make it not scratch the film. What about the other $5? That's for the screwdriver! Here's a way to turn the tables. Take a file to your gate, and install it using the k3camera.com instructions: http://www.k3camera.com/k3/k3s16mm-install.php
  9. Now that I think about it, the notion of hand-cranking a 'sync' camera makes very little sense. :huh: Those are some massive motors on the NNCs. The motor I used is a 'double-stack' motor--a cube about 2.25" on each side. Fits easily in the palm.
  10. Hmm. 1) Mitchell 2) Mitchell Standard 3) Mitchell HS ("High Speed") 4) Mitchell GC ("Government Camera?") 5) Mitchell NC ("News Camera") 6) Mitchell BNC ("Blimped News Camera") 7) Mitchell BNCR ("Reflexed") Are #1 and #2 the same? Was the original Mitchell called just a "Mitchell"? Ok, so the NC has a single (1:1) drive shaft in the lower right of the motor side. That would be #5 #6 and #7 The Mitchell HS has the 8:1 shaft in the center, with the 1:1 shaft in the upper left corner. Are #1, #2, #3 and #4 all like that? From the web: "Mitchell introduced the much quieter NC [for 'Newsreel Camera'] in ca. 1930. The cameras were hand-cranked, later motor-driven. 744 NC's were made." That would imply the Mitchell NC had an 8:1 shaft, because I can't imagine hand-cranking at 24 rpm. (With an 8:1 shaft, you turn at 2 or 3 rpm for 16 or 24fps). So...is the lower right shaft a 1:1 or an 8:1? :unsure:
  11. I had to mount the Revolution 121 time-lapse/single-frame motor on a Mitchell 35mm, and while I was at it, I decided to see if I could drive the camera at sync through the 8:1 shaft. It worked (click the link for videos and pictures). Does anyone know what kind of Mitchell that is? And more importantly, what other Mitchell cameras have the same shaft layout. The badge on the camera says "Mitchell Camera Corp, West Hollywood, No. 504" It's a rackover.
  12. Clive! I didn't realize you were so sensitive! I mean, your Bolex sync motor, being designed in the 1970's, had to use 1970's technology! The original poster simply asked if there was a motor that ran at 4fps. You said that that wasn't possible. You were wrong. You said it wasn't possible to design a crystal-sync motor for the Eyemo. You were also wrong about that. First of all, the motors we use are properly described as brushless synchronous AC motors. Synchronous means that the motor speed is controlled by the frequency of the applied signal. Brushless means there are no brushes, in that you have to externally commutate the motor. Now the colloquial term is 'stepper motor' because it's a lot easier to say then brushless synchronous AC motor. Second of all, a 'stepper motor' doesn't do anything without being driven by a driver of some kind. If you use a 1970's-style driver, then you get the classic situation you describe, since the old-style drivers use a square-wave. The Revolution Motor, being revolutionary :), doesn't use 1970's technology. It uses an ultra-modern driver that generates a sine wave (to be specific, a pair of sine-cosine waves). Thus, the motion is silky smooth, without the noise and vibration of a geartrain and DC motor combination. But let's be honest Clive. Nobody would design a single-frame motor using a gearmotor. First of all, unless you change the gearing, you're limited to just one shutter speed, and it's a wild shutter speed! There's no regulation of the motor speed whatsoever. Just because you regulate the voltage applied to the motor, doesn't mean the speed is regulated. It is possible to get varying shutter speeds from frame to frame. The real reason you designed your single-frame motor using a 1950's-style gearmotor, is because in order to use a digital motor, you need to use a digital microprocessor! Since you don't know how to program microprocessors, you didn't have any choice. You had to use a gearbox, coupled with a little microswitch (I'm assuming--have never looked inside of one), with some kind of 555-timer circuit to generate the interval. Writing software to control a single-frame motor is not as easy as you'd think (as Nick discovered). Using a gearmotor is much easier. But the benefits of digital microprocessor control are incredible: Crystal-controlled shutter speeds. Multiple shutter speeds (from 1/8 to 1/2 sec, 1 sec on up ) Crystal-controlled intervals Automatic shutoff External light control (turn the light on a few seconds before the motor turns). No gearbox to wear out and cause noise and vibration! ...this list could go on until it got really boring... Ok, we've talked about single-frame. Now let's talk about Sync. The Revolution Motor is plenty smooth at single-frame operation and even smoother when running at sync! So #1 and #2 are silly. Exactly! Since the Revolution Motor uses a synchronous motor, it is simply not possible for it to run 'out-of-sync' ! The motor must rotate at the speed determined by the applied sine wave. If the motor can't handle the load, it will let you know with a very audible indication. A motor using a phase-locked-loop (PLL) and encoder needs a warning light because otherwise you can't tell if it is running at sync or not! Now remember when I said it wasn't easy to write the software to control single-frame operation? Sync is much harder! The software has to accelerate the motor to the desired speed, run it that speed, keep track of how many frames have been filmed, handle the 0.1% slowdown weirdness if running at the video speeds, decelerate to a stop, and then park the shutter! Let's look at the advantages. First of all, there's no brushes to wear out, you can have the motor turn at any speed you want, you can park the shutter, ramp the speed, and you don't have to watch the sync alarm. You can even have the motor turn an exact number of frames and then stop! . But there is another big benefit. Remember your Arri II motor debacle? Why did that happen? Well, the technique of using a PLL to control motor speed doesn't work so well when the motor is attached to a camera with a less-then-perfect drivetrain. Slop in the gears leads to surging in the motor speed and flicker in the footage. And a small army of incredibly upset filmmakers. Just as you pointed out in #1, your motors have trouble dealing with cameras that have slop in the drive train. That doesn't make your motors bad, it is just a consequence of using a PLL for motor speed control. The technique of using an AC syncronous motor is way older then the 1960's! I've read that in the earliest days of sync-sound filming, they would use syncronous motors in the camera and in the sound recording equipment, both run by the same generator, to assure sync. The Revolution Motor is a 21st-century version of that concept, with the microprocessor generating the AC drive frequency. And a whole lot more. It's not the cheapest motor out there, but as my late grandfather told me, "Only a wealthy man can afford cheap tools". ;) I didn't mean to offend you by describing your motor as 'ancient technology'. I don't even think I mentioned your motor directly. Let me state that I have installed and sold many of your Krasnogorsk-3 Sync Motors. Never had a problem with one! And what do I keep on the workbench to check sync? I'm sure this looks very familiar to you. Three of the LEDs were dim so I replaced them with orange ones. It's a handy little gizmo, nice solid feel, looks and works great! My only complaint is that you need a screwdriver to change the speed. Ultimately, Clive, any camera motor exists only to enable the creativity of the filmmaker. We can leave all the technical mumbo-jumbo aside and state that anything that limits the creativity of the filmmaker is bad, anything that enables the creativity of the filmmaker is good. The Revolution Motor lets the filmmaker unleash his or her creativity. Shooting Animation? Want a 1-second shutter speed? Half-second? Eighth-second? No problem. 15-seconds? No problem, but maybe you should turn on some lights. Shooting Time-Lapse? Want a 180-degree 'shutter angle'? Just dial it in, 1-second interval with a 1/2 second exposure. Want flowing, dreamy footage? Set the interval to '0' and bump-up the shutter speed? Not sure of the interval and shutter speed settings? Set the Presets and auto-expose with the Chaining feature. Shooting Sync? Go ahead, shoot straight at 24fps. Or slow it down to 4 fps and see what comes out! Cap the shutter, auto-backwind, and layer another exposure on top! And remember, that's all with one motor, on any Bolex, early or late model. You've given me an idea for a slogan. Unleash Your Creativity with a Revolution Motor Hmm. I'll have to think about that. :rolleyes:
  13. Let me see if I understand this correctly. You tried to copy the Revolution Motor, and your copy didn't work as well as the original? Wow, imagine that. :unsure: From your description, it sounds more like you tried to copy the 'ThingM' motor or the Meritex 'ITSM' motor. I will give you some pointers...after I respond to my friend Clive. :rolleyes:
  14. Our Revolution Motor for the Bolex (also available for Eyemo, Filmo, and more) will run from 1 fps to 48 fps, all crystal-sync, and also do the video speeds. Heck, it will even run backwards! Read more about it here: http://www.intervalometers.com/rev/bolex/ You can watch it running at 4fps here. It uses modern microprocessor control so it doesn't have the limitations of sync or single-frame motors based on ancient 1970s technology. ;) There's a Time Lapse/Single frame only model (which will run up to 6 fps sync), and one that does all that and adds sync 1-48 fps plus the oddball video speeds (29.97 and 23.976). Oh, and I should mention that it has a full range of time-lapse features, including multiple shutter speeds and crystal-controlled intervals. Also programmable-shutoff, automatic filming, and lots more. And it drives the 8:1 shaft present on all the Bolex models, early and late, and it will even fit the EBM. The TimeFlow (TIV) Intervalometer with Turbo Mode can run at 3 fps, but you have to ask that feature because (as of 2007) it's a custom feature. (In 2008 it gets added as a standard feature) Bolex Krasnogorsk-3
  15. Ok, that's a different problem. You want to find the correct alignment of the main driving sprocket. The sprocket has two setscrews that hold in on. See the screwdriver on the right in this image? Let's call that setscrew #1. You want setscrew #1 to go against the flat on the sprocket drive shaft. If you take the baffle plate out, you will be able to see where a flat spot has been cut into the sprocket drive shaft. In the middle of the drive shaft, it's not round, but D-shaped. After you take the baffle plate out, turn the mechanism until the flat spot is at about 5 o'clock, just like in the picture. Carefully put the baffle plate back in, and when you tighten setscrew #1, it should hit that flat spot. If you get it close, it will naturally auto-align as you gently tighten the setscrew.
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