Film-Tech Forum ARCHIVE: New 70MM releases

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Posted by Michael Cornish (Member # 6529) on 06-18-2018, 07:08 PM:

What format are both new 70MM releases and new prints of classics done in? 5/8/10 sprockets? Classics being struck with org mag strips or are they being done DTS?
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The theater I am thinking of reopening has 14 screens with 3 "main" ones. Those 3 I would look into combining into one with a curved screen. I would make a smaller booth in the auditorium for 70/35 projection.....ahhh change over days.

Any and all input is welcomed!

Posted by Scott Norwood (Member # 30) on 06-20-2018, 03:27 PM:

New 70mm prints are 5/70 with DTS sound in one of three possible formats: 5.1, special-venue, and 8-channel. Older 70mm mag prints still exist and any self-respecting 70mm venue needs to be able to accommodate them as well (including five screen channels' worth of sound). 8/70 and 10/70 are really special-venue formats for museum installations and such, and are not ordinarily used for "normal" theatrical features.

If I were designing an auditorium for 70mm exhibition today, I would look closely at the D-150 concept, wherein a large 70mm curved screen can be masked down for a somewhat smaller picture for 35mm screenings. I would want 70mm to be the largest picture format available. The major downside to having a big, curved screen is that the projection booth must be level with the center of the screen, as keystoning looks awful on curved screens. I am not sure of the current state of digital cinema with respect to curved screen projection, but that is worth investigating as well to see if it is viable.

Any film venue being considered now (when every print is potentially an archive print) needs to have reel-to-reel capability. Rightly or wrongly, archival prints are not generally made available to platter houses. A 70mm booth needs to be somewhat spacious, due to the size of the reels and shipping containers (as opposed to 35mm).

This is where I ask you to please not do this unless you want to do it right. Which means that you need the help of technicians and operators with significant experience with the 70mm format. There are probably fewer than a dozen venues in the US that can put on a good 70mm show without damaging the print. Please don't be one of the other ones that damages the few remaining prints, screwing over the reputable 70mm houses.

Posted by Phillip Grace (Member # 2262) on 06-20-2018, 08:25 PM:

I'm a bit wary about deep curved screens. The depth effect can be spectacular, but it only works for a limited number of people in the audience - those near the centre and front - the majority of the audience will be seeing a picture with some degree of distortion. There are also issues with uniform focus and stretching of the image around the curve. Having the projector set level and square to the centre of the screen is vital - with only the smallest tolerances allowable. This requirement will have a direct influence on the layout of the seating. Most likely, the whole audience will be looking upwards to the screen to some extent. As Scott rightly points out the D-150 system does most to address several problems associated with deep curved screens. Their range of lenses were designed to project various film formats onto their own curved screen. Their Curvulon lens will focus the whole 70mm image around the curve with the screen at its largest size. Screen results are compromised when conventional projection lenses are used on a deep curve.
Thus far the new 70mm releases have appeared with conventional image geometry. A print with differential optical squeeze across the the width of the image is required for correct results on curved screens. No doubt this can still be achieved if special prints are made.
Because the 70mm set-up will have to co-exist with conventional DCP projection I would be more in favour of a "flat" screen for all purposes. The 70mm results will still be extremely good.
The Pictureville Cinema in Bradford has the optimum solution to the problem. They have a deep curved screen for their Cinerama presentations, and a completely separate flat screen which hangs in front of it for other formats. There is also a second set of stage speakers which are set up behind the flat screen.
There have been a number of designs for screens with variable curvature, which offers another approach. I believe the Drake theatre in Plymouth U.K. actually had one installed.