Film projection surface.

[Jacob]

We are in the middle of setting up a community cinema.
A large area of wall to be built and plastered (where the stage is in the pic on the web site http://www.cinemamiddleton.co.uk/ ).
Can we use it for projection, instead of buying a screen? Would special paints help? Anybody have any experience of this?
Projection area proposed 16' x 9'.
Instead of screen we could have curtains to protect the surface.

 

[Eric The Viking]

That would work well.

You want the most matt white paint you can find - any reflections will reduce the detail you can see, and make the image look dull. Stay away from "beaded" paints, of the type used for reflective clothing and other similar things. The beads use total internal reflection (like cats'-eyes) to bounce most of the light straight back where it came from. The effect is that the angle of view of the screen narrows, both vertically and horizontally, bad news for a small space (relatively speaking).

There may be a special paint for screens - I don't know for certain, and there may also be a special vinyl wrap, that you can apply to something like MDF. I konw exactly who to ask - a friend who used to run a scenic services company for TV and events. Back later...

 

[novocaine]

there is special paint for it with lots of pseudo scientific bumf to back to up and take away your 90 quid a tub.
the wall needs to be perfectly flat, I don't mean skimmed flat I mean completely flat, as flat as a flat thing from flat town Norfolk (you can insert your own smutty joke here about flat things). there in lies the problem, getting a flat wall is harder than you might think.
next problem is keeping a wall white, it will fade to yellowish fairly quickly, will get smudges and the like on it, some young SOB will draw on it you get the idea. the paint also needs to be the same thickness all over so you don't get different absorption in spots, best bet is to spray it rather than roller it.
theres a few other negatives for painting it but they are the biggies.
not that any of this really matters if you're viewing it from 10ft away, but people will tell you it does.

joy of a screen is it is flat from the out set, is the right colour, the same density with the same albedo (because space terms sound cool) and it wont fade with time. obviously cost is an issue, so is fitting it, pulling it up/down and wear and tear on it to think about too.

I can see both sides of the argument, you can get a a bigger screen for you bucks by painting it, it's a no brainer, just be aware it might not be perfect.

oh and paint a black boarder round it, apparently this makes a difference according to those in the know (nice crisp edge to screen helps with eye strain)

 

[Droogs]

Have look at the AVforum website, This covers lots of options for home cinema, but some of them are pretty massive. i got my old 3m screen through a recommendation on there. Don't have it now unfortunately or you could have had it Live in a small flat now)

https://www.avforums.com/

 

[bugbear]

My company sometimes does trade shows, and we have a large printed graphic for our stand, with logos, quotes etc. We just left part of it white, so we can use a PC projector to give demonstrations; works fine. Much more convenient than hauling a big monitor around!

BugBear

 

[Jacob]

Thanks all for that. Lots to think about!
Re. flatness - the logic is obvious but I'm told that just a reasonably practicable degree of flatness will do, e.g. a good plastering job followed by careful sanding. Defects become apparent the further away the viewer is from square on central behind the projector. In fact a roll up screen will have all sorts of folds and creases which will show up if you shine a torch across the surface but invisible from square on normal projection/viewing positions.

 

[novocaine]

A modern screen is ostensibly flat when up, there shouldn't be any folds or creases, that's why they roll instead of folding. any lumps and bumps are very gentle which makes a huge difference too. It's the difference between a good screen with decent support and a rubbish one.
Everything else is correct though, the further off centre you go, the more obvious it becomes, as you are projecting for "cinamatic" purposes though, I'd expect only half the people to be in the right place, the rest will be off to the left and right of the screen.
I guess a couple of coats of white paint to try it isn't going to cost you the world, if it doesn't work for your purposes a screen can be added at a later date.

 

[Jacob]

A modern screen is ostensibly flat when up, there shouldn't be any folds or creases, that's why they roll instead of folding. any lumps and bumps are very gentle which makes a huge difference too. It's the difference between a good screen with decent support and a rubbish one.
Everything else is correct though, the further off centre you go, the more obvious it becomes, as you are projecting for "cinamatic" purposes though, I'd expect only half the people to be in the right place, the rest will be off to the left and right of the screen.
I guess a couple of coats of white paint to try it isn't going to cost you the world, if it doesn't work for your purposes a screen can be added at a later date.

Good idea!

In the past we've had stretchy plastic screens which press-stud on to a frame (Stumpfl), flatter than a roll up screen. But these are quite difficult to erect at bigger sizes - you need several people to pull them out tight enough. I've got a feeling that the wall idea might end up being better than a demountable mobile screen - there's a trade off either way.