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Author Topic: Port Hole Question
Jay Glaus
Expert Film Handler

Posts: 119
From: Pittsburgh, PA USA
Registered: Dec 2010


 - posted 02-08-2013 09:01 PM      Profile for Jay Glaus   Author's Homepage   Email Jay Glaus   Send New Private Message       Edit/Delete Post 
Hello all,
I'll be installing a Barco 23b in the drive in soon, and I'm getting stuff ready. I'll be putting in my port hole soon, and had a few questions I'm sure someone out there has had experience with. First, I'm planning on using a 1'x1 hole. I'm trying to figure out how far off the ground to put it... I've been told to start the bottom of it 3 foot off the ground, 4 foot off the ground, I've also heard the picture is about 50~51 inches off the ground. Where should I start my port hole? My main booth which is still 35 mm starts the port hole 4 foot of the ground. I imagine you can raise the machine up higher if you need to, but I'm trying to go for the simplest installation. Also, I've heard about slanting the glass. My main booth which has a port hole already slants the glass down so any reflection is shot back towards the ground. I've been told I should slant by some, and I don't need to by others. The ones that said to slant say that you want any reflected light to not be shot back into the lens, but rather up or down. Others say I don't need to slant if I use anti reflecting glass. I personally think I should slant, I think no matter what glass I use, there will always be some light that goes back into the lens if it's flat, and that doesn't sound good to me. I don't think the direction of the slant matters as much as the fact if it is slanted or not. Let me know what you guys think! Thanks!!!
Jay

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Dave Macaulay
Film God

Posts: 2170
From: Toronto, Canada
Registered: Apr 2001


 - posted 02-08-2013 11:19 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
12x12 should be OK. A "B" on a standard Barco pedestal is rather high, and although it's easy to jack it up quite a bit it doesn't go lower than somewhere around 50-52" lens centre. Any up tilt for drive-in can be done by mounting the projector "backwards' on the pedestal or by using just the projector or pedestal jacking legs but this will raise the lens regardless... place the port high, the projector and pedestal have about a foot of lift available between them! Setting the port hole window bottom edge at 50" minimum should be safe but a bit higher won't hurt.
Angling the port glass back a bit isn't a bad idea. Light going back in the lens won't hurt anything, you want to get any internal reflections in the port glass off screen though. It's a big issue with 3D systems with a flat glass front (hello, Real-D) where you can get nasty ghost images reflecting back to the screen if the glass is vertical. But I don't think drive-ins have a digital 3D solution that works so far and polarized is definitely out.
Note that the lens is well off to the left of centre of the projector when you locate the port. You want room on the right to service the lamphouse. The light engine is serviced from the left and you should provide some room for any work in there but the lamphouse has to slide out maybe 15" to the right to get it out for lamp changes. Same for the main circuit boards on the right.

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Brad Miller
Administrator

Posts: 17695
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 02-08-2013 11:41 PM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
quote: Dave Macaulay
I don't think drive-ins have a digital 3D solution that works so far and polarized is definitely out.
Dolby 3D works just fine.

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Jay Glaus
Expert Film Handler

Posts: 119
From: Pittsburgh, PA USA
Registered: Dec 2010


 - posted 02-09-2013 01:52 AM      Profile for Jay Glaus   Author's Homepage   Email Jay Glaus   Send New Private Message       Edit/Delete Post 
Thanks Dave, that's some good info to have! And Brad, i thought I heard something about Dolby 3D in a drive in setting. I was always curious how 3D was coming along for drive ins. I went to CinemaCon these past three years (actually I was there back when it was ShoWest) and from what I was told and understood, there was a type of 3D that wasn't real good for a drive in, then there was another that was, something about polarized vs shuttering I think. I never looked into 3D quite all that much yet, just getting the machine in first. My thoughts were the giving and getting back of 3D glasses in a drive in setting. (this would be an interesting topic for me to start on here, I'm tempted to) but I always was afraid of people leaving with the glasses, cause as far as I knew the glasses were pretty expensive, unless they came out with the cheapy ones for this yet. Since the drive in has 1 exit for all 4 screens, and a lot of times intermission hits around the same time on each screen in the summer, I'd have 400 cars with glasses in with about 950 total to get glasses back from, I was always afraid no one would be able to get out, cause I don't think they'd give them back unless I had a lot attendant there collecting. I've also thought of having them check their drivers license to get the glasses and getting it back when they returned the glasses. And if anyone left their drivers license for a few pairs of 3D glasses, that's pretty hard core. Of course, all of this goes out the window if they did come out with the cheapy glasses. I know I couldn't give them out at the box office, there's no room... Literally. There's barely enough room for the ticket punchers to work together without bumping into each other every 2 seconds. I figure I'd give them at an EZ up tent in the field, they just have to bring their ticket over. Heck, on 35mm when people got frustrated about no 3D I used to joke for them to cross their eyes ever so slightly and they might get the effect if they do it just right [Smile] Anyhow, that's my view on 3D at a drive in, don't know if anyone has anything to add. Probably not, cause you wouldn't expect to find a discussion about this under a port hole question... Think I'll go start that topic now.

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Chris Slycord
Film God

Posts: 2986
From: 퍼항시, 경상푹도, South Korea
Registered: Mar 2007


 - posted 02-09-2013 01:59 AM      Profile for Chris Slycord   Email Chris Slycord   Send New Private Message       Edit/Delete Post 
Dolby uses passive glasses, btw. It doesn't use active shutter glasses. But it also doesn't use polarization.

And its glasses aren't cheap like the throw-away Real-D ones, but you just collect the glasses as the people drive out. Not really that hard.

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Jay Glaus
Expert Film Handler

Posts: 119
From: Pittsburgh, PA USA
Registered: Dec 2010


 - posted 02-09-2013 02:58 AM      Profile for Jay Glaus   Author's Homepage   Email Jay Glaus   Send New Private Message       Edit/Delete Post 
Chris,
Cool, never knew that about Dolby's glasses. I guess as far as the whole collection thing you're probably right, I just tend to over think things, many things.

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Carsten Kurz
Film God

Posts: 3868
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 02-09-2013 07:50 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
I'm wondering how many DriveIns actually use Dolby 3D? I mean, with THAT light loss, even a stacked projection setup will have trouble to light a DriveIn screen appropriately.

Choices are very limited, I guess. Shutter systems would be possible, but somehow the sync signals would have to be distributed into the cars. There are RF systems available now, but no off-the-shelf systems yet. Plus, the gain in light efficiency between Dolby 3D and Shutter is there, but not huge.

There is a new, brighter Infitec version, but to my knowledge, not for the cinema business. I guess Dolby has exclusive rights for Infitec in the cinema market?

Coming back to the port hole topic - does someone have their portholes mounted in a tilted position to minimize reflections further?

- Carsten

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Dave Macaulay
Film God

Posts: 2170
From: Toronto, Canada
Registered: Apr 2001


 - posted 02-09-2013 08:25 AM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
There's only one 3D drive-in I have heard of, outside of Dallas in a fairly deserted area with relatively dark sky. According to a technician who was there shortly after the 3D installation 2 years ago, the 3D image brightness was "considerably less than adequate".
I can't find any other 3D drive-ins listed anywhere: possibly if it had been acceptable some other place would have done it in the last two years? Having one location putting on bad 3D shows doesn't mean Dolby 3D "works" at drive-ins, it only means that some delusional fellow tried it. And apparently the rest of the industry saw the result and said "umm... nope.".

As to port hole tilt: lots of port glass is tilted, but you don't need to especially with coated optical glass. Drive in port glass can be pretty poor since it gets weather on one side. Did you have any port glass for 35, or just shoot out a hole (pretty common at drive-ins here)? I think you need glass for digital just to keep some of the bugs and lot dust out of the booth.

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Carsten Kurz
Film God

Posts: 3868
From: Cologne, NRW, Germany
Registered: Aug 2009


 - posted 02-09-2013 10:26 AM      Profile for Carsten Kurz   Email Carsten Kurz   Send New Private Message       Edit/Delete Post 
I hear about tilted port glass a lot, but I hardly ever see it. At least in Europe.

Maybe they think, a tilted projector, as common in most booths/screens with downward projection, is enough tilt against an upright wall with a built-in portglass?

- Carsten

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12299
From: Annapolis, MD
Registered: Dec 1999


 - posted 02-09-2013 02:02 PM      Profile for Steve Guttag   Email Steve Guttag   Send New Private Message       Edit/Delete Post 
Tilting the port glass keeps light from re-reflecting back into the lens. Depending on the projection angle, the glass is effectively tilted. If you have ever seen credits on screen that have what seems like a another set of credits scrolling down (but dimmer and out of focus)...that is often caused by a projector and port that have essentially the same angle to each other.

As for drive-in and 3D. As others have pointed out...light is your chief obstacle. That is...keeping unwanted away and putting as much as possible out there. If I were "forced" into doing it I would:
1) Still try to talk them out of it
2) Go with Dolby 3D because active glasses would be too expensive to put in people's cars.
3) Get the screen tower painted with about as high a gain as possible (remember, this may limit your field for ALL shows, not just 3D)
4) Use a 2-projector set up with as bright a lamp as possible (NEC need not apply...even with an 8K lamp it is dimmer than its competitors, except Sony, of course).
5) Still try to talk them out of it
6) Use anamorphics for Scope
7) Possibly reduce the image size for 3D presentations to get more light
8) Remind the exhibitor after half of the glasses drive away that I tried to talk them out of it.

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Mike Blakesley
Film God

Posts: 12492
From: Forsyth, Montana
Registered: Jun 99


 - posted 02-09-2013 08:28 PM      Profile for Mike Blakesley   Author's Homepage   Email Mike Blakesley   Send New Private Message       Edit/Delete Post 
I don't think 3D in a drive-in would be too good because you are too far from the screen for the picture to fill most of your field of vision.

In this OP's case, if he has one exit with some cars having 3D glasses and some not....well that might be a colossal pain come exiting time.

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