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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Picture Shake (Page 2)

This topic comprises 3 pages: 1  2  3

Author Topic: Picture Shake Paul G. Thompson The Weenie Man Posts: 4718 From: Mount Vernon WA USA Registered: Nov 2000 posted 02-18-2004 10:57 PM                     I also agree with Brad and Gordon. As far as I am concerned, lot of test film is pure garbage. Isn't automation the most wonderful thing you have seen to get the crap flying though the door? What ever happened to good old days when the quality goes in before the name goes on?  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-19-2004 12:10 AM                     I agree that the perfs are a good refrence if they are visible but when using RP-40 one can actually use it as a guage to meaasure jitter and weave. Hence it has a bit more meaning to it. Mark @ CLACO  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-19-2004 10:25 AM                     The same method used with 35PA of projecting a shadow on the screen and comparing it to the movement of the image can be used with the perfs and get an accurate answer  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-19-2004 07:53 PM                     Gord, So how much of a perf is a quarter of a square ? Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-19-2004 08:17 PM                     Measure it as % movement  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-19-2004 08:57 PM                        I don't have a copy of SMPTE RP40 with me here in Montreal, but I recall that there are 200 squares across the width of the image, so each square is 0.825 / 200 = 0.004125 inches on each side. Therefore, a quarter of a square represents about 0.001 inch of movement. The KS perforation is 0.1100 x 0.0780 inches in size.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-21-2004 07:48 AM                     Mark, you are so wrong about the image movement on 35-PA. There are several processes that go into its final outcome. First, that film stock has its perforatinos punched as 4-perf sets as opposed to release print film where it is continious punch. Then there is the edge slitting and how it relates to the perforations. The camera used to shoot 35-PA is pin-registered, not edge guided. What showes up on the screen is a culmination of how well the perforations are aligned to edge of the film. Even the pulling of the aperture plate test will give a false projector attribute if the perforations are skewing in relationship to the edge of the film. This problem has been noted by the facility that makes 35-PA. As to BH-1866...it is the wrong pitch for projectors, period and not a valid test. You should test with a close a material as what you are going to use. BH-1866 is the proper test for Tele-cine work though. I have had many hundreds of feet of reject 35-PA that completely relate to the how the film was made prior to it ever entering the camera. The current batch we have seems to be pretty steady this time. So far, all 35-IQ (magenta) have been steady and all Schneider CLT test film has been steady. That is another indication of 35-PA's guilt...other films are steady in a projector where 35-PA was not. Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-21-2004 10:03 AM                     Steve, I too have had bad batches of 35PA but not in a very long time. In fact it was back before the camera was either replaced or overhauled and 35PA was really horrible as per frame to frame tolerance. The present batch we are using is actually superb. And while the camera being used used to make 35PA definately does not use edge guiding...no B&H type, Mitchell, or Panavision movement does, but there are in fact many professional cameras in daily use that do rely on edge guiding for lateral steadiness. Those include Arriflex 2A,B,C, 3C, and all B&H Eyemos that serve as crash cams, all Eclair Cameflex's, almost all ultra high speed cameras and some of the effects cameras out there. The fact that these cameras not only rely on it for lateral steadiness but the fact that many of these cameras produce images nearly as steady as a pin regestered movement is clear proof that the accuracy of the perfs is excellent. As for the pitch there is no argument that it is different but it only means that there may be one perf against a tooth on a 16 tooth sprocket at a given time and this actually makes the film in itself more of an acid test. Unfortunately there are those that do look at the perfs rather than measure steadiness..... In fact Steve I use my Schneider CLT film as a refrence to compare and evaluate any 35PA that comes in. They have all been excellent, were they not we wouldn't be using it. Perhaps John P. would like to chime in on how accurate the tolerance of the perfs is kept in relation to the edge of the film. I'm sure that Kodak is extremely proud of how tight they are able to keep this on a daily basis. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-21-2004 07:57 PM                     "Unfortunately there are those that do look at the perfs rather than measure steadiness....." That is the correct way to measure it since the 35PA is not usable for that function  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-21-2004 10:46 PM                     So Gord, How many inches of perf equals .001 inch of movement? Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 02-22-2004 12:39 AM                     Mark, I have actually had John measure some 35-PA due to its unsteadiness...he found it to be within spec. It still shook on screen..you could tell where you were in the loop due to picture movement. It hasn't been that long since I had a bad 200' roll of 35-PA and the manufacturer of 35-PA regularly complains about the lack of tolerence on both the perforation skewing and slitting width and wishes the allowances were cut in half. One of the ways he checks his camera is to shoot the target, back the film up reshoot it and then shoot it again...if alignment is perfect there should only be one target on the film not a smearing of three...they always come out as one. It is interesting to note that Schneider CLT is not on Kodak stock (I don't think 35-IQ is either). I agree that the last batch of 35-PA we received was pretty steady though. Steve  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-22-2004 09:45 AM                     Steve, Thats the standard double exposure test used for all cameras and its a really good way to verify camera and film, but more difficult to figure out which is bad when things go wrong. Its pretty much SOP to do with any rental camera before it goes onto a production. In over 20 years of using the film I just have not had the shake problem you mention when running RP-40, only the frame to frame steadiness problem which no one could do anything about at the time. What projectors did this occur on for you? I normally get it in 200 foot rolls, perhaps twice a year..... If John found the film to be within spec I'm sure it was ok. You really need either an electron microscope or projected optical comparator to check anything of this accuracy. Kodak may even use other means to check accuracy.....hello John P., are you out there...... Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-22-2004 12:15 PM                     One of the Kodak engineers had us completly releive the band of a JJ so the perfs completly could be projected for registration and slitong tolerance tests  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 02-22-2004 12:29 PM                       quote: Thats the standard double exposure test... Its pretty much SOP to do with any rental camera before it goes onto a production. Mark is right, this is tantamount to running Dolby tone in a soundhead.  |  IP: Logged John Pytlak Film God Posts: 9987 From: Rochester, NY 14650-1922 Registered: Jan 2000 posted 02-22-2004 03:38 PM                        Kodak uses electromechanical gauges for the most critical measurements. Humidity and temperature of the measurement facility must also be carefully controlled to the standard, which I believe is 50% RH and 20 Celsius. I don't know if I saved the measurements of Steve's 35-PA test film, which I shared with him almost two years ago. The SMPTE vendor (Stan D.) used to work more closely with Kodak in "hand selecting" films for use in making 35-PA. Now I think most are just "off the shelf", but he has not returned any film for dimensional measurements in a few years. Kodak worked closely with Schneider when they were developing their test film prior to the release of Star Wars Episode 1. It was originally printed on Kodak stock, but I'm not sure about now, since it is all printed in Europe. Are you sure 35-IQ is not on Kodak color print film?  |  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.