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Author Topic: Cinemeccanica Victoria 5 film run speed Tony Smith Film Handler Posts: 42 From: worcester,worcestershire, england ,UK Registered: Sep 2012 posted 02-27-2015 10:50 AM                     Hi Folks Very much a newbie to this world, very interesting it is too. After a little advice, and help Please. I have after my first thread manaaged to run a Cinemeccanica Victoria 5, at slower run speed, by changing the motor high speed frequency setting in it's Mitsubushi single to three phase invertor. My question is, what is the best method of checking its new run speed, we are going to try and run 20 frames per second achive film (protection copy ) I have built from a kit, a LED twin bright leds, stroboscope, which its max flashing speed is 20 hz. I have tried looking at the shutter running and strobing (at the rear end where the spindel comes out) Is there a better way to do this and get a stationary image when the strobe is in sync? Tony Smith  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-27-2015 11:43 AM                       An easy way is to cut a loop some multiple of 20 FPS. Say 100 frames long exactly. Run the loop and count the clicks as they go thru the gate and it should go thru 10 times exactly in one minute. Repeat as needed after tweaking the speed control. Helps to have a footage counter to make a perfect loop.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 02-27-2015 01:33 PM                        If your motor runs at 24fps at normal mains frequency (50Hz in the UK), then you can work it out using simple maths. 20 is 5/6 of 24. 50 / 6 = 8 and one third Therefore, set your inverter to 41.66Hz (or as near to that as you can get it), and you should be running at 20fps.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-27-2015 03:46 PM                       Should is the operative word. I'm just doing some of these and there can be a little loss or slippage. A tach that reads the output of a shaft encoder or the loop method I described are closer to proof over a period of time.  |  IP: Logged Tony Smith Film Handler Posts: 42 From: worcester,worcestershire, england ,UK Registered: Sep 2012 posted 02-27-2015 04:31 PM                     Hi Folks Thank you for your answers I have changed the frequency from 50 hz to 41 hz, the projector at 41 hz is running slower,just trying to get my head around who to measure the actual speed now. Thanks again folks will try your tips out Tony Smith  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-27-2015 08:20 PM                        As a guy who always thinks in audio terms: Use a 1000 Hz loop and a frequency counter. For 24 frames=1000 Hz. Do the math for other speeds. (Works upward for 30 frames as well.)  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-27-2015 09:20 PM                       Oy, Louis, Where is one to find 1K loops at this late date? And it was never that accurate in the first place. Dolby Tone is all over the place freq wise and is certainly not 1K in any case. Other than that, great idea!  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-28-2015 03:41 PM                        I still have lots of 1k. Yes, I counted it and it looks to be off by about 1 Hz. Made back in the day when tight parameters were specified by John Moseley, even though they didn't affect anything we were testing?? Carl Greenberg used this technique to get 30 fps for Oklahoma in 70mm. (Threaded 35mm optical at the same time as 70mm film was playing ) 1250 Hz=30 fps. Yah, I know!  |  IP: Logged Tony Smith Film Handler Posts: 42 From: worcester,worcestershire, england ,UK Registered: Sep 2012 posted 02-28-2015 05:10 PM                     Hi Folks Thanks again for your answers, just one quick question, if I could. The Cinemeccanica Victoria 5 has a two blade shutter, so as the film rate in 50 hz is 24 frames per second,so I would expect the shutter rate to be the same, so it lets the light through when the film is stationary in the gate, so with a twin blade shutter is the actual run speed 12 frames per second,or is the speed 24fps and the film same frame shown light twice. I know this is a basic question to you guys but as a newbie, still trying to work thse things out Tony Smith  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 02-28-2015 05:18 PM                     It actually flashes the same frame twice to reduce flicker. 48 flashes per second.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 02-28-2015 08:34 PM                       I measured SMPTE 1K tone 20 years ago last time and it was more than 3% off 1,000 Hz. Sir John Mosely must have been drinking that week! Of course 1K was made by more than one entity and the absolute freq, was never considered critical, it was just for a relative level. The level recorded on the film also varied from year to year or whenever a new negative needed to be recorded. Hollywood test films were pretty sloppy back in the day. I can hear Steve's shoes approaching or reproaching so I better sign off. Lot's of ways to measure film speed but the whole point is to get it dead on seeing as there is now a way to do it. All we could do is complain about it before variable frequency drives.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 03-01-2015 07:27 AM                     Put a solar cell in front of the lens and use a frequency counter on the flashing of the shutter  |  IP: Logged Tony Smith Film Handler Posts: 42 From: worcester,worcestershire, england ,UK Registered: Sep 2012 posted 03-01-2015 07:42 AM                     Ji Folks Thanks again for your replies, have learn't a lot from your forum and the memebers on it. I think what I will try first is using a stroboscope, put a mark on the spindle with the dual blade shutter on, check it speed of rotation, looking for 48 rps in 24 frames, and note the change when running 20 frames, looking for 40 rps,or as near as possible. All this due to the cinema being booked for a film showing conference, where a fair amount of archive film shot around 20frames is to be run, a request was put in for us to blow the dust off the 35 mm Cinemeccanica Victoria 5, and show the film as it was intended. thats not off a DVD. Tony Smith  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 03-01-2015 08:20 AM                     I would go with Sam's loop method. No fuss, no guessing, and as accurate as your stopwatch (unless you can't count frames in the loop or passes). There are many frequency meter apps for iThings® if you want to try more complicated solutions.  |  IP: Logged Leo Enticknap Film God Posts: 7474 From: Loma Linda, CA Registered: Jul 2000 posted 03-01-2015 03:36 PM                        By all means go for complete accuracy if it's important (or if people are breathing down your neck), but as an aside, the people who shot the movies you're going to show probably didn't. If you're being told 20fps I'm guessing that you're showing British and/or French movies from the mid to late 1920s. Most of the Hollywood studios were shooting at 24 (and specifying projection at 24) from the early '20s onwards. Germany and the Soviets mostly stuck at 16-18 right up until the conversion to sound. 20 was typically used by British and French studios as a compromise between not driving up film stock costs too much, and using a fast enough frame rate that the emerging picture palaces (longer throws to bigger screens, hence the need for more light) could project a reasonably bright, low-flicker picture. The point is that until the conversion to sound, most of these studios used hand-cranked cameras. If the operator was aiming for 20, the actual speed of each shot could be anywhere between 18-22, and could even vary within a shot. When Kevin Brownlow was doing his "Thames Silents" video versions in the 1980s and '90s, he would meticulously adjust the transfer speed of each shot to try to achieve a consistency of movement across the movie as a whole. They look great - "better" than original audiences would have seen, in fact. So in one respect, you really don't need to worry about getting the frame rate bang on, because that was neither achievable nor expected during the silent period. The need to sync the frame rate accurately and reliably between the camera and the projector only materialised with sound. Very few people can see a slight (as in, 2-3 frames per second) speed difference in the image, but they'll very easily hear it on the audio: the same 2-3fps difference is enough to make a bass baritone sound like Mickey Mouse.  |  IP: Logged

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