Can you Project 70mm on Reel To Reel???

[Yves Leibowitz]

I am curious. I am testing to see if a 70mm on our Century JJs works. We noticed when starting up the motor the film bunches up after going through the lower feed sprocket below the intermittent. But when starting up AND manually starting the take up reel the film speed becomes regulated??? I have run 70mm before on platters along with IMAX on platters too. Never 70mm on reel to reel though. From what i understand most places run 70mm on platters and few places run it on reel to reel and if they do they have to start it up the same way I did and monitor the reel while another projectionist is doing the same thing on another projector. Can someone confirm please and offer suggestions if they can???. Thank You.

[Leo Enticknap]

Yes, 70mm can be run reel-to-reel and I have done so many times. What you describe sounds to me like a worn and slipping belt driving the take-up spindle. If it's OK with 35mm but slow to start with 70, this suggests to me that it can't handle the additional weight of the 70mm reel. If the belt in question is a roundthane one, the ends might have stretched out of the plug a bit.

[Dave Macaulay]

In my experience you need a slip hub reel for 70mm, much like for large 35mm reels. House reels, either wire or the Goldberg cast ones, are better than the sheet metal distribution reels. If the film does go slack, the reel will eventually speed up to take that up... the film can skip on the output sprocket (goodbye loop) and bend things like cue sensors when it snaps tight. Tightening the reel drive clutch may help but once tight enough to spin up a 70mm reel, the sprocket will probably buzz for the first part of a reel.

[Brad Miller]

You are probably trying to takeup using a reel that has a hub smaller than 8 inches in diameter. Never do that. Also be forewarned there is a much higher chance of damaging sprockets (especially on older 70mm acetate prints with mag tracks) if your reel to reel setup has too high of a tension for feed or takeup. Unless you are just going to run the show a couple of times, for a normal run of a couple of weeks or more there will be less wear on the print if you use the platter.

[Jim Cassedy]

Yes- 70mm can run reel-to-reel. I do it all the time. As others have mentioned, ideally you're
take up reel should have a 'floating hub" - We don't have any of those at my theater, but with
careful adjustment of the take-up clutch, the normal reels work just fine.

[Steve Guttag]

I'd say, the VAST majority of my projecting career (now into its 4th decade), 70mm has been show on reels. The chief exception would be when I was at K-B Theatres and ran the K-B Cinema from about the fall of 1982 to about the fall of 1983. That was run primarily on a platter with 35mm trailers on reels or screenings on reels. Despite K-B being very pro-active on platters, all 70mm venues were equipped with 2-projectors (at least through my tenure there...so late-'80s). The philosophy was...we never lose shows and we definitely will not lose a show in a 70mm venue. We don't just have a spare tire, we have the whole car, so to speak. They were set up to run the platter to either machine or to run changeover in both 35mm or 70mm...despite, again, platter being the "normal" way.

Conversely, at the Uptown in Washington DC, that was a changeover venue up till early 2005 and ran a lot of 70mm...all reel-to-reel.

I agree on using floating hub reels and I also agree on 8" hubs with 22" flanges (70mm standard).