Not quite "home" cinema.

[chriscubed]

The school I work at put on a musical or play every year in our hall, but this year constructing the sets as they usually would has become infeasible.

We're looking at using projectors instead, to project the sets onto a screen (or 3!). We've seen it done at another school, and while what they did was impressive, they used traditional front projection, which left shadows on the sets and actors being projected onto.

So we're looking at using either short throw front projection, or rear projection. I think if it's rear projection then we would still need it to be short throw, or we will struggle for space behind the curtain.

We have a short throw projector in a classroom currently (an Hitachi CP-A221N) which does the job admirably on a small screen, but I think we may need something a little more powerful (and perhaps better quality?) for the size of the stage backdrops.

Does anyone have any experience with larger scale projection? Or some knowledge of what kind of projectors we might need?

As usual with schools, the deadline is tight, we need to have the whole system set up in 4 weeks, including creating the virtual scenes!

 

[lucid]

I have a lot of experience dealing with projection - both front and rear - in both the commercial and home cinema markets.

Unless you have a very large budget then I think you should stick with front projection.

Here's a quick rundown of the basic pro's and cons of each

Rear projection - Pro's

• Best contrast and potentially the brightest image
• No shadow
• Requires less projector power

Rear projection - Con's

• Depth required at rear of screen
• High cost of rear projection material
• Image brightness drops away quickly for off axis viewers*
• Hot spot (bright distracting light) in the image when viewed on-axis*

* both above can be solved with a rigid light focusing screen, but the costs are enormous


Front projection - Pro's

• Easiest to do without specialist equipment
• Most cost effective solution
• Widest viewing angle for audience
• Lower risk of hot spot is using a matt projection surface

Rear projection - Con's

• Needs bright projector to compete with stage lighting
• Unless flown high, the projector is in the action zone on the stage

The other issues are screen shape vs set design shape, and the lens capabilities of the chosen projectors. Projectors display a landscape format image. So you couldn't have a tall narrow portrait format set screen without wasting a lot of the light power of the projector. The lens determines the minimum and maximum throw distance which in turn determines the smallest and largest screen sizes. The consequence of screen size is image brightness. Ask the physics dept about the impact of the inverse square law. Spreading the light over too large an areas washes out the image.

None of the problems are insurmountable. But it will take a little creative though and a united approach with set- and lighting- design as well as stage direction to make this work effectively. There's also the budget to consider.

If the school already owns two or three high brightness auditorium projectors - say 4000+ ANSI - then as long as they don't have very long throw lenses on them then they would be my first choice. Mount them at about 10ft and point them down at the scenery screens.

 

[chriscubed]

I have a lot of experience dealing with projection - both front and rear - in both the commercial and home cinema markets.

Thanks for the detailed reply, much appreciated.

Unless you have a very large budget then I think you should stick with front projection.

Great, front projection was my preference as I had no experience with rear and am a bit daunted by the setting up of the rear projection material.

The other issues are screen shape vs set design shape, and the lens capabilities of the chosen projectors. Projectors display a landscape format image. So you couldn't have a tall narrow portrait format set screen without wasting a lot of the light power of the projector. The lens determines the minimum and maximum throw distance which in turn determines the smallest and largest screen sizes.

Brown is the stage area, black is the side and rear curtains.
White is roughly what we were thinking for the 3 screens, though it may change somewhat yet.

The other school we visited said to use 4:3 scale projectors and not widescreen, but I see what you mean about the height problem. I'm going to do some measurements tomorrow if not before, which should give me a rough idea of how wide the screens will be and therefore the proportional height we can go to.

Out of curiousity, can projectors be mounted at a 90 degree angle and pointed downwards for a 3:4 ratio instead of 4:3?

The consequence of screen size is image brightness. Ask the physics dept about the impact of the inverse square law. Spreading the light over too large an areas washes out the image.

I thought this was the case - is it simply that we just need a more powerful projector for the larger screens? I guess having the measurements would help.

None of the problems are insurmountable. But it will take a little creative though and a united approach with set- and lighting- design as well as stage direction to make this work effectively. There's also the budget to consider.

Creative thought is what we're going to need I think. There should be some money with which to buy equipment for this but it's not going to be a huge amount.

If the school already owns two or three high brightness auditorium projectors - say 4000+ ANSI - then as long as they don't have very long throw lenses on them then they would be my first choice. Mount them at about 10ft and point them down at the scenery screens.

We only have 1 high brightness projector at the moment, and I think the lens is medium throw - certainly not very long throw but I'm doubtful it will work from 10ft away.

The 10ft figure - you mean 10ft away from the screen?

 

[lucid]

It'd probably take a couple of hours to do several sets of sketches with enough detail to show you what's possible. That's time I just don't have at the moment. But if you are happy to have a 20 minute chat on the phone then we can bounce some ideas about and come up with something tailored to your production. Let me know in this thread and I'll trust message you my number

 

[chriscubed]

Thanks, I might take you up on this some time next week - been off work with flu for the last 2 days, and they've had a few meetings without me so need to catch up.

 

[lucid]

If you do want to contact me then you'll need to configure your Trust account.