my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » FP20 running slow (Page 2)

This topic comprises 3 pages: 1  2  3

Author Topic: FP20 running slow John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-10-2003 09:21 PM                        quote: BTW, a quarter of a second is six frames. That does not strike me as particularly precise. 6 frames in 1440 is reasonable accuracy for this type of measurement. That's less than 1/2 percent.  |  IP: Logged Florian Pausch Film Handler Posts: 11 From: Wien, Austria Registered: Dec 2000 posted 02-11-2003 01:58 AM                     Hi, Michael, a useable device for really quick measurement of the running speed is a handheld TV frequency counter, normally used to check the line frequency of TV and computer screens. Here in Austria, I get these from ELV/Conrad electronics. best wishes, Flo  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 02-11-2003 04:05 AM                        quote: Because the DTS players use a phase lock loop (PLL) to lock the timecode to the projector speed (motor) Do you have to thread a loop of film through the dts reader and sprockets to move it or is the phase picked up at the motor itself? Florian, which part number in the Conrad catalogue is it?  |  IP: Logged Florian Pausch Film Handler Posts: 11 From: Wien, Austria Registered: Dec 2000 posted 02-11-2003 09:40 AM                     Michael, it is: ELV-electronics "Screen-check SC-200", Part Nr. 68-314-86, € 9,95  |  IP: Logged Karen Hultgren Master Film Handler Posts: 492 From: Agoura Hills, CA, USA Registered: Mar 2000 posted 02-11-2003 11:49 AM                        Michael, You do not need to thread film. We lock to the projector motor. Karen at DTS khultgren@dtsonline.com  |  IP: Logged Jim Spohn Film Handler Posts: 95 From: Bakersfield, CA, USA Registered: Jan 2003 posted 02-11-2003 01:35 PM                     The last time that a speed problem came up several people posted some very clever ways to check the speed. Steve Kraus had the one I thought to be the most clever, using a solar cell in front of the lens with the cell hooked to a meter in the frequency counter mode to count the shutter passes. The most simple however appears to be the 5 second loop. The loop can be run thru an infinite number of times for timing purposes. The more times the loop cycles, the greater the resolution. It's simple quick and dirty and anyone can do it with no special tools or equipment and end up with amaising acuracy. My hat is off to all you clever guys!!...Jim  |  IP: Logged John Hawkinson Film God Posts: 2273 From: Cambridge, MA, USA Registered: Feb 2002 posted 02-11-2003 04:27 PM                     Err, Karen, . We're talking about a regular DTS-6D with the standard timecode reader? --jhawk  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 02-11-2003 04:57 PM                        That is what confused me too. But Karen is referring to the dts-6AD. Still, I don`t understand why this is necessary when the dts-6D works effortlessly just from the timecode reader?  |  IP: Logged Karen Hultgren Master Film Handler Posts: 492 From: Agoura Hills, CA, USA Registered: Mar 2000 posted 02-11-2003 05:36 PM                        I am talking about checking projector speed with the DTS reader and the DTS-6/-6D/-6AD players. All of them have the PLL circuit that act in the same way. And, I made a mistake, you do need to run film. The reader needs to be sending speed info the the player. Use the 1kHz tone and monitor it at the output of the player. Karen at DTS khultgren@dtsonline.com  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 02-11-2003 06:11 PM                    Paraphrasing myself from just a month ago: If you want to check the speed you can use a solar cell, perhaps an old mono one out of your junk box, otherwise get a cheap one at Radio Shack (or UK equivalent), connect it to your DVM set for frequency measurement, and hold it in the light beam. With a 2X shutter (double blade or single blade, double speed) you will be looking for a deviation from 48 Hz. With a three-blade 3 blade look for 72 Hz.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 02-11-2003 06:15 PM                        So we figured out some inventive ways to determine if the projector is going slower or faster than 24fps. OK, you clever lads....NOW WHAT?! Finding out if it's slow or fast is a piece of cake -- doing something about it is a lot more vexing. It's not as if these things have a speed control on them, eh? Induction motors are not about to be coaxed into going faster or slower than what they want to go at, and the synchronous babies, if they are not going at the right speed, then you really have a complicated problem going on, or maybe even a few of them. Sometimes it may be better not to know Frank  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 02-11-2003 06:41 PM                        Stupid semi-relevant question: what's the difference between the FP20 and the current-model FP30? Is the FP20 mechanical or electronic (the FP30 comes in both versions)? Are there other differences? They look very similar in photographs, but I've never seen an FP20 in person.  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 02-11-2003 11:55 PM                     Getting back to the "5 second loop" how would one calculate how far off speed the projector was? If for example when the measurement started, the splice could be heard at the 3,8,13,18 ect. points on the second hand, yet five minutes later they were falling at the 2, 7, 12, 17 ect. points, what lower speed would this represent? Calling professor Criswell.....  |  IP: Logged Daryl C. W. O'Shea Film God Posts: 3977 From: Midland Ontario Canada (where Panavision & IMAX lenses come from) Registered: Jun 2002 posted 02-12-2003 01:40 AM                        So in your example: 24fps x 300s / (300s - 3s + 2s) = 24.08fps actual speed  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-12-2003 11:01 AM                     Well you could misalign the sound head to scan the perfs and that should be 4x24 or 96 HZ on a frequency counter  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 3 pages: 1  2  3

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.