Film-Tech Forum ARCHIVE: Screening room question

This is topic Screening room question in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=001696

Posted by Harry Robinson (Member # 265) on 12-02-2000, 12:52 AM:

After a year and a half, the old screening room is beginning to come together.
We have moved into our new home and I have the entire upstairs for the theater.

The area is 31'4" by 13'10". Ceiling is 7'6". Roof corners encroach three feet of ceiling starting at 5'11". So I have 10' of unencumbered ceiling. I can hang a 5' X 12' front-mounting snap screen from 78" which leaves me 18" floor clearance.

We are building an 8 X 10' booth at one end of the room, and I will be hanging the screen 2'4" from the back wall in order to allow for speakers and access to an attic.
Throw distnace should be around 22'. I am elevating the projector 1'4" which will put the lens at a little more than 5'.

My question to you guys who have dealt with this before is, will this work?

I have a 5' X 11'6" screen on order. It will give a little more floor clearance, but I hate to sacrifice image size. Let's face it. That's one of the biggest rushes about this hobby. If you guys say go with the smaller screen, I'll bite the bullet. If you think this could work at 12', I can call and change it on Monday morning.

Posted by Brad Miller (Member # 2) on 12-02-2000, 01:53 AM:

Anything can be made to work. Buy the biggest possible screen you can cram into that room! You can get the proper lenses later.

P.S. You should consider building a platform for the projector console, or building up the entire floor. Otherwise you will have heads in the way. Also, purchase a silver screen. Harkness makes the best screens in my opinion.

Posted by Pat Moore (Member # 380) on 12-02-2000, 06:44 AM:

Here's my two cents worth, Harry.

Yep, this would work -- sightlines are the only issue. Since you're raising the projector it will help, but I assume all seating is at floor level.

Lenses are nice, 50mm Flat and 75mm Scope, somewhere around there. You've got a 34-degree or so viewing angle from the last seat location, so the image will "appear" meadium-large sized.

If you've got room to do it, go to 12ft width. You'll only need it for CScope, but you might miss it if it's not there. The Scope picture would "want" to be around 12.5 wide.

I might disagree a bit with Brad, depending on your light source and lenses, on the type of screen. A matte surface will always look nicer to me if you've got the light for it.

Pat

Posted by Martin Frandsen (Member # 74) on 12-02-2000, 08:17 AM:

You could type your data into the Schneider lense calculater program to see if everything fits. www.schneideroptics.com/

Posted by Harry Robinson (Member # 265) on 12-02-2000, 09:12 AM:

Thanks for the input. I'll go the 12 foot route. Incidentlally, I am raising the projector about 1'3". That should put the lens elevation at right around 5'5". And we are raising the floor 1" for sound isolation purposes. We're also double drywalling and using eggshell insulation. The top layer of drywall on the room side is a sound-dampening board used in recording studios.

I'm lucky to be living in Nashville. The guy whose doing the work has built dozens of studios and knows about acoustics. I also got some good advise from David at CPI.

Sound no problem...picture, I'm a rookey.

Posted by John Pytlak (Member # 331) on 12-04-2000, 08:06 AM:

I also agree with Pat on going with a matte (gain=1) screen for a home screening room. On a small screen you'll have plenty of light with almost any xenon lamphouse, and the matte screens aren't directional like the gain screens, so getting good uniformity will be much easier. You should also consider using a 3-blade shutter to minimize flicker, since you probably will still have plenty of light for a small screen and don't need the higher efficiency of a 2-blade shutter.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Eastman Kodak Company
Research Labs, Building 69, Room 7419
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com

Posted by Bill Purdy (Member # 202) on 12-04-2000, 09:49 AM:

I would suggest that you build your projection booth floor as a free standing platform. If it is attached to the walls it will transfer vibration through them. There is a company called "Mason Industries" (http://www.mason-ind.com/) who make all sorts of vibration dampers and they have series called "Super W" which come in nice little 2" square pads. YOu put one of these under each of your supporting posts. (Be sure that some of your posts are right under the projector.) When you build your platform make it about 1" to 1 1/2" shy of the available space and before you set the platform in place staple some old scrap carpet around the sides so that the platform won't travel and touch the walls.

------------------
Bill Purdy
Component Engineering

Posted by Harry Robinson (Member # 265) on 12-04-2000, 08:13 PM:

Bill, thanks for the tip about the floating floor. The contractor who is doing the room has done recording studios in the past and is familiar with some sound isolation techniques, but I'm going to run this info by him when we meet later this week.

John, I'll ask the tech who is helping me with the installation about the three-bladed shutter. I would not have thought of that.

As usual, you guys come through with the goods.

Posted by John Eickhof (Member # 323) on 12-05-2000, 12:25 AM:

Hi Harry! Glad to see you are moving along! I
have various 3 blade shutters in stock!
I used them in my home screening room, I strongly recommend it for a nice SMOOTH picture! You will have plenty of light!
Also, go to the 12' plus screen if possible! Also, when it comes to lenses, I have many NEW & used ISCOs in stock! Later...John

Posted by Rory Burke (Member # 512) on 12-05-2000, 08:07 AM:

Look for SMPTE literature on design of small monitoring/review rooms for proper specs. Surround soundmagazine also has excellent tips on acoustics and viewing angles etc. REmember that the audience or crritical listening position (mixer)is important when planning where and how big your image should be. An ideal screening room has the dementions of 16 x 9 x 24. Your audio is also heaviliy dependent where you listening position is as far as speaker positioning is concerned. THX (uh oh dont start please) i belive just came out with a new post mixing monitoring and mastering standard for small rooms just like what you have going there.

Rory

Posted by John Pytlak (Member # 331) on 12-05-2000, 10:33 AM:

You could also look at Widescreen Review magazine for ideas on home theatres:
http://www.widescreenreview.com

Posted by Martin Frandsen (Member # 74) on 12-06-2000, 03:11 AM:

Maybe a question for John Pytlak, what should the correct angel of a projector be in a small screening room? - any tips? I would like to place the projector as correct as possibel, THX recommends with-in +/- 5%, i guess that would be the rule in a large house, but also placing the projector ''dead-center'' will throw the light back into the lense ( CONTRAST KILLER ) - the ideal placement i can come up with now would be slightly over ''dead-center'' maybe 2-3%, so the projector is ''beaming'' down very slightly?

Posted by John Pytlak (Member # 331) on 12-06-2000, 07:13 AM:

The "ideal" is perfectly orthogonal (no angle) to the screen. Any angle at all introduces "keystone" distortion. Light reflected from the screen back to the lens is negligible. However, it IS VERY IMPORTANT to angle the PORT GLASS to not reflect light back to the lens. And to use optical quality port glass with anti-reflection coatings.