|
|
This topic comprises 7 pages: 1 2 3 4 5 6 7
|
|
Author
|
Topic: There's a Brand New 70mm Print of "2001" BUT . . .
|
|
|
|
|
Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
|
posted 10-24-2016 03:56 PM
The diameter of the 70mm profile is wider because it has to pull the film down five perforations rather than four for 35mm, so it has to rotate through a greater linear distance. The amount of force acting on the film is the same for both 35 and 70, because the entire drive train - motor, transmission components, and intermittent unit - are all the same. Also, keep in mind that the DP70/AA was designed for use with acetate film (and to a lesser extent nitrate, a small amount of which was still in circulation when it was designed), which is thicker and heavier than polyester. So 70mm polyester stock, with no magnetic oxide on it, should not be stressing the gears in the intermittent unit under normal circumstances.
Also, the moment of force is more evenly distributed across the intermittent shaft on 70 than for 35, where it's concentrated on two points closer to the center, so if the gears in the cross box were worn or damaged, I'd expect the noise and picture stability to be worse on 35 than on 70, which is not the case. When it's running 35, you would not be aware of any problem with that projector.
I'm not ruling out an intermittent unit problem, especially as we've investigated everything else we can think of that could be causing the noise. But I'd be a little surprised if that turns out to be the sole cause.
| IP: Logged
|
|
|
|
|
|
|
|
|
|
Leo Enticknap
Film God
Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000
|
posted 10-24-2016 06:04 PM
Actually, I'd welcome all the help I can get from armchair repairmen (and women!). This issue has been bugging me for the two and a half years I've been working at the Cinematheque, and the only reason I've not been prioritizing it is because we know that it isn't damaging film and there have always been more urgent/critical/deadline-attached/show-threatening things that are higher up the list.
I forgot to mention that the noise only happens when the machine is configured for 70mm and film is running. The projector sounds fine when the motor is running, with 70mm components fitted, but no film threaded. So it has to be caused by the film abrading against something. Scott - I'm ashamed to admit that swapping the pad rollers with those from the other machine didn't occur to me, though the gate did. I will try this as soon as I get a moment. The gate bands are almost new, so I'd be surprised if it were those, although, as with the pad rollers, that would fit with the problem not being there with 35mm. Again, will try a swap and a loop test as soon as time allows. Thanks, folks.
Steve - the only explanation I can think of is that we've been looking at different LOA DCPs. Unfortunately I can't give you the UUID of the one I liked, because we played it before I introduced new DCP screening report forms on which we note the UUID of the CPL that was actually played. But I wouldn't be surprised if multiple versions were made and I saw a later one than you: this has happened with DCPs of blank check restorations of other titles, after all.
| IP: Logged
|
|
|
|
Jonathan Goeldner
Phenomenal Film Handler
Posts: 1360
From: Washington, District of Columbia
Registered: Jun 2008
|
posted 10-24-2016 09:55 PM
quote: Steve Guttag
I do take exception to your characterization of the DCP of LOA...I have found it to be the most embarrassing DCP transfer I've ever seen. It is an absolute (bad) joke. I screened it on a Christie 4K system and even did freeze frames to see if I could tell was was going on. Then threw up Samsara (also 4K DCP) to see if it was possibly a projector/configuration problem...Samsara was razor sharp and a very good representative of a 65mm/4K DCP transfer.
I, for the life of me, can't figure out what you like about the LOA transfer. Oklahoma! was also night and day better than LOA on its 4K DCP transfer. In fact, it probably looked the best of the classic titles that got the DCP "treatment." Though they absolutely fumbled on the audio for it. They didn't think to have a 6-channel version of it as a "VF" for those that could run it. I have no problem with 5.1 being the standard and it is great they made an Atmos version, but one should always preserve the original as the reference. It was an academy award winning mix, after all.
actually the DCP of "2001" I saw over at the Arclight Bethesda, was by the most hideous looking transfer I've ever seen - edge enhancement galore, no sharpness to speak of, image looked soft at times, the image wasn't steady and bumped up and down for no reason. I actually had to ask one of the managers at the intermission, "this is a DCP presentation?" "yes", "oh really" [shakes head in disgust] If this is what Warner's is giving out to theaters to showcase a classic SciFi movie - I'm floored.
| IP: Logged
|
|
|
|
|
|
|
|
Brad Miller
Administrator
Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99
|
posted 10-25-2016 01:49 PM
Although I've not had this issue with the DP70, I've seen multiple Century JJs strip out their intermittent when running 70mm due to the additional stress of the pulldown.
Assuming the JJ is properly aligned for 35mm and the 35mm pull down is effortless in the first place, just switching over to 70mm typically doesn't magically put things into ideal alignment (despite popular belief). Typically turning the mechanism down by hand is harder with 70mm due to the slight difference in alignment (which is different between film stocks and also mag vs. dts).
For those of you with single lens JJs, put some 70mm film in the machine and turn it over by hand using the shutter knob and note any additional stress as the intermittent performs it's pull down. Then with the other hand very slightly start to open the gate a millimeter at a time as you continue to pull down via the inching knob with the other hand. Notice how much easier the entire mechanism is as the gate pressure is released ever so slightly.
While it is possible to get the 70mm gate/trap aligned acceptably to run both mag and dts 70mm prints (along with different thicknesses of mag prints), even that isn't truly ideal because if an average alignment is achieved for various 70mm thicknesses on the JJ, the 35mm alignment will typically be too loose once the parts are exchanged to run 35mm again. This is why most JJs exert more pressure (and wear) than need be on 70mm.
While there is a trick to the single lens JJ projectors to permit a one-off alignment for 70mm without impacting the 35mm alignment, it is impossible to do on a turret JJ due to the gate design. This is why I am very much not a fan of people running 70mm on JJs with a turret, as it can only truly be aligned for one type of film being ran at a time. Sometimes this differential can be minimized by shimming the 35mm gate, but typically its not enough.
If running the print dry, the mag tracks also create additional stress on the film and intermittent with any oxide shedding as oxide collects in the gate. While not immediately noticeable, this buildup of oxide is also destructive to the mag tracks with every pass. Wax will help a little bit with this, but not nearly as much as FilmGuard. Plus the wax will over time create additional dirt on the print.
When running wet with FilmGuard, there is no hint of mag wear (which is not just a JJ thing). The FilmGuard also keeps the film and gate/trap lubricated so the intermittent has much less work to do for each pulldown, and as a result the intermittent will last longer and also the sprockets will have less stress put onto them, which in turn means the intermittent sprocket teeth will also last significantly longer before they become "hooked". (Plus of course the print is cleaner and base scratches are hidden from projection.)
A number of people, including a number from this forum, have been in various booths where I've ran 70mm (either commercially or at my home screening room) and the more frequent comments are "that projector really runs 70mm super quiet" or "that projector runs 70mm film quieter than my 35mm projectors run film". That's because of the careful gate/trap alignment and lubrication (via FilmGuard).
Pro tip: Find yourself a random old and brittle scrap of 70mm acetate film with heavily damaged (specifically torn) sprockets. Get a good high resolution photograph of a the sprocket damage and then run that in a loop for an hour on the machine. (Make sure the loop is carefully guided and protected with 70mm rollers. Don't just let the film drag over the projector shell or over the upper spindle, with or without something soft on the spindle. Use an actual roller so you aren't inflicting any wear to the print other than what is actually being inflicted by the projector itself.)
Afterwards re-photograph the same frames of the print from the pre-run photos you took and very carefully compare them on your computer monitor for any additional sprocket wear (blow the high resolution photo up very large). If you've got it all aligned properly, you should not be able to detect any additional sprocket wear inflicted to the print from your projector. (And obviously if the loop is breaking on you, then your projector is absolutely not aligned properly and even when running a good condition print you will be inflicting some degree of wear to it, even if not directly noticeable on the bench after one pass.)
In regards to the #2 DP70 projector of Leo's, keeping in mind I am not a total expert with the DP70 model, my suspicion based upon the info presented above is that it will likely be one of these things:
*Azimuth of gate to trap (or gate/trap assy to film path) is off.
*Intermittent sprocket lateral alignment is not centered with respect to gate/trap.
*Gate/trap tension is too great. Remember this will cause the film to buckle very slightly in the gate (not usually visually noticeable, but will cause the center of the projected image to be out of focus).
*Hooked sprocket teeth, likely on the intermittent sprocket, but could be any of them.
*Intermittent show pressure is too great or the alignment from shoe to intermittent sprocket is off.
Remember, it's not going to be possible to visually tell if these are off just by looking at it.
As a super quick test I would also put the #1 70mm kit into #2 (with junk film of course) and see if the operational noise level drops to normal as a quick test to rule out something within the actual 70mm kit for the #2 machine.
Finally don't forget Fotokem doesn't have the ability to add the anti-static and scratch-protection that Deluxe and Technicolor added when they were processing prints. As a result newly made prints will be more susceptible to scratching than older prints. (For example, if an unused reel of Titanic was around today printed by Deluxe and a new Fotokem print of the same reel was printed today and both were spliced together on one reel and projected on "not-perfect" equipment with "less-than-stellar-operators", the Fotokem reel would suffer scratching on a given level of abuse faster than the older Deluxe print would. I'm not bashing Fotokem's quality by any means, just pointing out that they don't have the capability that used to exist back in the heyday of film printing by the big boys. Because of this, people have to be BETTER projectionists and must have TRULY properly aligned systems when running new prints even moreso than older prints.
Sadly that doesn't seem to be the case. What seems to be the case is that a bunch of theaters are latching onto a pair of 70mm projectors and running 70mm festivals. It only takes ONE of these venues to quickly destroy the entire 70mm library between all of the studios because there is typically only ONE PRINT left in circulation. When that print is scratched, it's going to take a LOT (such as footing the bill for a new print) to get a replacement struck. What's terrible is that this is currently happening at a record pace as has been noted by Leo and a number of other people whom have handled the 70mm print library recently.
The two biggest offending things regarding scratching is due to MORONS (yes there is it, I said it) running 70mm on JJs without removing the 35mm pad rollers as well as said moron understanding proper loop sizes of 70mm. Each other projector model has it's own little quirks, but in speaking of the most commonly found 70mm machine in the US, the JJ requires more skill than just "put the 70mm kit in and let's roll".
Although my personal love is for the JJ over the DP70, at least the DP70's design requires a special level of stupid to damage a print on it, unlike most other projectors.
| IP: Logged
|
|
|
|
|
|
All times are Central (GMT -6:00)
|
This topic comprises 7 pages: 1 2 3 4 5 6 7
|
Powered by Infopop Corporation
UBB.classicTM
6.3.1.2
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.
|
Home
![[Smile]](smile.gif)
Printer-friendly view of this topic