projected scenery
Printed From: Community Theater Green Room
Category: Producing Theater
Forum Name: Set Design and Construction
Forum Discription: Post your questions or suggestions about designing or building a set here.
URL: http://www.communitytheater.org/forum/forum_posts.asp?TID=5019
Printed Date: 11/23/24 at 5:18pm
Software Version: Web Wiz Forums 8.05 - http://www.webwizforums.com
Topic: projected scenery
Posted By: stanberry12000
Subject: projected scenery
Date Posted: 3/26/11 at 2:03pm
| I would like to project the scenery for The Full Monty. Probably on a screen that will be 20' WIDE and 10 feet tall. Any ideas. Will Powerpoint work? |
Replies:
Posted By: vickifrank
Date Posted: 3/26/11 at 5:34pm
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Basically yes, you can use powerpoint through a computer linked projector. But there are a few other concerns....
1.) Aspect ratio. This is the width:height ratio of your screen. In your case its 2:1. More typically its 4:3 or 16:9 for most projectors.
2.) Is your projector strong enough? For 20' wide you need at least 5000 lumens with XGA resolution. I'm not an expert in this so this is based on a few rules-of-thumb.
3.)Front or rear projection? (See next question because distance upstage or downstage matters) Front projection can have actors casting shadows on the scenery. Rear projection has the difficulties of space and 'hot spotting'.
4.)Where do you locate the projector? (If you are projecting on a scrim you want a steep angle) For a normal projector you need to have the projector about 16 feet away to get the 20' wide image. For a short throw (wide angle lens) you need about 13 feet. For an ultrashort throw (special very wide angle) you need about 6 feet. If you have the projector, look up the throw distance to find out how big an image you can get at a certain distance. For rear projection you can shorten this distance up to a half with the use of a mirror--but be aware this requires some fiddle/experimentation time.
5.) What is your screen? If it is a screen that exists you can test some of the above now. If you don't have that screen then there are the scrim vs. screen questions (addressed and discussed in a recent post here) and the cost concerns. ------------- _____________ http://www.studio-productions-inc.com 1-800-359-2964 The theater scrim people |
Posted By: David McCall
Date Posted: 3/27/11 at 5:39pm
Here is an image to show the principal behind folding a projected image using mirrors. These drawings are based on a 30' throw yielding a 20' picture.
 In the first set we are folding the image horizontally. Picture H-1 shows the normal horizontal cone. Picture H-2 is that same cone but it is folded very close to the screen to minimize the space needed behind the screen. I've added a second fold to reduce the width needed.
In the second set we have placed the mirrors vertically. Picture V-1 shows the normal vertical cone. Picture V-2 is that same cone but it is folded very close to the screen to minimize the space needed behind the screen. I've added a second fold to allow the projector to be mounted above (or below) the screen.
One thing you will notice is that the mirrors get pretty big if you want to cut the distance by much. Obviously the mirror can be smaller if you don't need to cut the distance as much. You can use any combination of horizontal and vertical folds.
An easy way to play with your ideas is to make a triangular piece of paper that is the right scale for the projected distance and screen size. I use graph paper. You can then fold the triangle any way you want to see how your folded beam is going to work. Traditionally you try to keep the folds at a 45 degree angle from the beam's center line. If you use first surface mirrors this becomes less important.
Big glass mirrors are going to cost a lot of money especially first surface mirrors. Rosco (the gel and paint folks) make a heat shrinkable mylar mirror that works pretty well if you do it right. You need a fairly rigid and very flat frame to stretch the mylar on. You don't want the mylar to touch anywhere except at the edges. Then you shrink it with a heat gun or hair dryer. I'm not sure how big you can make it using that material. ------------- David M |
Posted By: vickifrank
Date Posted: 3/27/11 at 8:25pm
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Nice diagrams, David. I have people ask all the time regarding mirrors and projection, usually, I simply tell them to allow 'fiddle time' to get it right--I'm going to direct them to this thread just to look at the diagrams and your discussion on the technique. Thanks for sharing this, this discussion will help a lot of folks! ------------- _____________ http://www.studio-productions-inc.com 1-800-359-2964 The theater scrim people |
Posted By: JoeMc
Date Posted: 3/30/11 at 11:25pm
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G'donya David your diagram's are great! Like others I normally mess about tweaking, for hours, with the mirror to bounce the light & adjust masking to suit [1:15]. Since I did 'A Chorus Line' I have been using the Rosco heat shrink mirror film which is much easier than muckin'about with glass mirrors & to produce the mirror size required. http://www.rosco.com/us/technotes/designer/data_sm.cfm - http://www.1950"s was sets projected on the cyc, especially for Opera. Which gave a 3 dimensional set piece, such as a flying horse or greek columns. It was accomplished via two slide projectors positioned on the first fly floors & the image projected on the cyc, I must admit it did look realistic. Aparently it was produced by taking photographs of a detailed stage model setting from two positions & then producing slide transparencies. They then duplicated the slide projectors to be placed in the same measured positions on stage, as were photographed on the model. I forgotten the name of the bod [A germanic name I think?] that devised this method, but it was a fantastic effect. ------------- [western] Gondawandaland "Hear the light & see the sound! TOI TOI CHOOKAS {may you always play to a full house!} |
Posted By: museav
Date Posted: 4/23/11 at 12:40pm
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Just be aware that mirrors do incur some loss or brightness, can introduce optical aberrations and if glass, need to be first surface (the silvering on the face rather than the back). One common difficulty can be how you mount them and provide sufficient ability to accommodate any required adjustments. Also, keep in mind that you can use mirrors vertically or horizontally.
Some other potential considerations:
The reality is that projecting general backdrops typically requires a large amount of physical space for the projectors and projection path and either very bright, and thus expensive, projectors or multiple projectors edge blended together to form one image. ------------- Brad W. |