Rear projection or front projection?

[NHStech]

My stage is 40' wide and 25' deep. Presently, anytime we do Powerpoint, etc., I have a projector I put in the first row in the house, and our screen is about in the middle depth of the stage. The computer coordinator seems fixed on the idea of, when money allows (he says perhaps next year), to get a mounted projector on the upstage wall and use a rear-projection screen. I can see some merits, but some cons. We use the stage primarily for concerts, but also for plays, musicals and a variety show. Any thoughts on whether front or rear projection is better? Screen size would not be an issue, so placement of the screen could be anywhere from all the way downstage to upstage. Also, installed screen, or screen you put up yourself? Thanks!

 

[gordonmcleod]

Rear projection has issues with sharpness and contrast as well as a narrower viewing angle for the audience plus a very noticable hotspot
also there are limitations to the size of seamless rear screen material

 

[JohnHartman]

You can get very large RP screen surfaces which are seamless... Stewart Filmscreens (no plug involved) makes them up to 40' X 90'.

RP is more tolerant to ambient light and several manufacturers have changed the make-up of the screen to make hotspots less of an issue and are more a factor of projector placement and lumen rating.

In a stage situation I would prefer a RP screen set because of the look. And with the stage being used for a variety of functions you would likely be better off with a portable screen so you do not need to be concerned with an installed screen getting damaged if it is up in the grid. It would be more work, but you wouldn't need to be concerned about it whenn it was not being used.

 

[coldnorth57]

I am for the use of a front projector mount in the FOH it then can be used for more things like for theatre as in Tommy or Miss Saigon or other shows that have a video piece in it ...if you get a powerful enough projector it will cut through the lights just finshed a show that i used 5 projectors all from the front on the cyc and on scrim one was 3500 lumens the others were smaller

 

[JChenault]

One nice thing about RP is that you can get a black or gray screen. These do eat up some light - but you don't have a big white screen on your stage at all times.

I have used the Rosco screen material and found it not too difficult to seam it together and the seams were not noticeable in our production. the Rosco RP is somewhat fragile - I would try to hang it and leave it up if I were you. It would likely get damaged if you installed it for every performance.

One thing to be careful of is viewing angle of your audience - and how much room you need behind the screen. The light from the projector tends to want to go in a straight line. This means that if your projector is too close to the screen ( and you have a super wide angle lens) the sides of the image will tend to be darker than the center.

Rosco has a set of pretty good articles on projection you might want to check out.
Rosco US : Technotes : Screens : Basics

I think the real question is what will you be using the screen for. From your post I could not get a clear sense of your use cases. If you want to show movies - don't use RP. If you want to have a dark background that you can project on - it might make a lot of sense.
John

 

[bdkdesigns]

Rosco RP is also impossible to get your hands on from my experience. We almost ran into a huge problem two summers ago when building the set for the Montana Rep national tour of To Kill a Mockingbird. The entire back wall of the set has RP material. We purchased a couple of rolls of it and could not find any more and Rosco was helping us in our plight to find some. Luckily we found remenants somewhere that gave us enough to finish the set.

 

[NevilleLighting]

I prefer RP for several reasons. First and foremost, I don't have to worry about actors casting shadows on the image and also don't have to worry about the image being projected on actor's bodies. Also, as mentioned before, much easier to control the effects of ambient light.

That being said, RP also has disadvantages. The primary disadvantage is throw distance. There is often not enough stage depth to project a large image. If you're just doing Powerpoint projections this may not be an issue, but it you are projecting a large scenic image it is very hard to accomplish from a rear shot.