Looking for a large perspex sheet to use as a projection screen.

27
Found 14th Nov 2009
What do you guys think of this?

Ebay item no: 400068289315

Any idea whether this will work? I'm not sure whether it's going to capture the light from the projector to make a decent image or if too much light is going to get through and shine straight in your eyes?

Alternatively I could use a clear sheet and try different materials under the screen to capture the image? A tablecloth is supposed to be reasonable, or tracing paper maybe?

Any suggestions most welcome!

Thanks.
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22 Comments
Original Poster
Carley;6891804

bad idea, get some proper projection screen material or paint your wall … bad idea, get some proper projection screen material or paint your wall white.



It needs to be a perspex sheet or something similar, it's a rear projection. It needs to be reasonably strong like a tv too, not just a wafer thin sheet.
Original Poster
Carley;6891850

MDF covered in projector screen material or painted white.



How does the projected light go through the mdf?
Carley;6891850

MDF covered in projector screen material or painted white, (the whiter … MDF covered in projector screen material or painted white, (the whiter the better.)



LMFAO oops! how do ya feel ?
renown;6891876

LMFAO oops! how do ya feel ?



you've got your christmas tree up early :whistling:
Carley;6891892

I see your problem now... is the perspex sheet that you suggested clear?


:w00t:
ClarityofMind;6891885

you've got your christmas tree up early :whistling:



Just making sure my lights work
Original Poster
Carley;6891892

I see your problem now... is the perspex sheet that you suggested clear?



No, opal. To be honest I don't know which sort would work best. Clear would be rubbish, needs something to catch the light.
renown;6891907

Just making sure my lights work



I see you're all plugged in already :whistling:;-)
Original Poster
Carley;6891920

Iv'e used a white sheet before in a tent when camping with a projector … Iv'e used a white sheet before in a tent when camping with a projector from the rear and the image was fine (obviously backwards but not noticeable unless you looking at subtitles!)



Yeah, I could use clear with a sheet or something but I think it's more likely to create problems rather than just using the right sheet in the first place!
TBH you would need to invest in some proper material for rear projection, otherwise you will have issues with image quality.
However that said you should be OK with a white cotton sheet, stretched over some clear perspex if need be, however unless the projector you are going to use has Keystone adjustment then you could find you get "hotspotting"
Original Poster
Carley;6891955

i don't know for a fact but i would imagine that 5mm perspex would not … i don't know for a fact but i would imagine that 5mm perspex would not let enough light through, the thinner the material then the better the image.



I could go for 3mm but it might be a bit floppy?

Or clear thicker with a sheet stretched over it?

Or something else???
Original Poster
bargain surfer;6892022

TBH you would need to invest in some proper material for rear projection, … TBH you would need to invest in some proper material for rear projection, otherwise you will have issues with image quality.However that said you should be OK with a white cotton sheet, stretched over some clear perspex if need be, however unless the projector you are going to use has Keystone adjustment then you could find you get "hotspotting"



Would you mind explaining the hotspotting bit more, As long as I've got the projector central I shouldn't need any keystone correction should I?
Benjimoron;6892040

Would you mind explaining the hotspotting bit more, As long as I've got … Would you mind explaining the hotspotting bit more, As long as I've got the projector central I shouldn't need any keystone correction should I?


IF the projector is central then the bulb is directly facing the viewing surface just like shining a torch head on onto a sheet, so the bulb would be the central hotspot. Simulate this with a torch right behind a sheet and you'll see what i mean.
However by keeping the projector at an angle to the viewing surface the bulb is then off centre thus eliminating "hotspotting," then in order to compensate for the angle of projection you would use Keystone adjustment to correct the image. Myself I have had my projector ceiling mounted and projected onto a wall, 210" of viewing pleasure, also just out of curiosity is there a specific reason you want to go rear projection?
Original Poster
bargain surfer;6892101

IF the projector is central then the bulb is directly facing the viewing … IF the projector is central then the bulb is directly facing the viewing surface just like shining a torch head on onto a sheet, so the bulb would be the central hotspot. Simulate this with a torch right behind a sheet and you'll see what i mean.However by keeping the projector at an angle to the viewing surface the bulb is then off centre thus eliminating "hotspotting," then in order to compensate for the angle of projection you would use Keystone adjustment to correct the image. Myself I have had my projector ceiling mounted and projected onto a wall, 210" of viewing pleasure, also just out of curiosity is there a specific reason you want to go rear projection?



Yes, all will become clear when I've finished!!!

Mainly for the fact that you can't walk infront of a projector normally.

I see what you mean about the hotspot, doesn't keystone correction mean you lose image quality? Aren't you then interpolating or whatever?
for rear projection of a decent size, you are gonna have a lot of wasted space behind the "screen"
I have like 4-5 metres from projector to screen, giving me 150" diagonal widescreen image, you gonna need a looooooong room for the projection space and then to be in front of the screen also.
Keystone hasn't seemed to have caused any picture problems what so ever with my setup
JayIce;6892372

for rear projection of a decent size, you are gonna have a lot of wasted … for rear projection of a decent size, you are gonna have a lot of wasted space behind the "screen"I have like 4-5 metres from projector to screen, giving me 150" diagonal widescreen image, you gonna need a looooooong room for the projection space and then to be in front of the screen also.Keystone hasn't seemed to have caused any picture problems what so ever with my setup


JayIce is right, you gonna need a heck of a long room to enjoy rear projection. Also Keystone adjustment will not affect the image quality, it merely changes the trapezoid angles i.e. /...\ & \.../
Translucent Coloured Perspex
• 31-37% Light Transmission...
I'm no expert, but I wouldnt of thought that 31-37% light transmission would be enough
heres a rear projector screen material supplier..
widescreen-centre.co.uk/Pro…tml

may give ya some info
also...
dazian.com/htm…tml

appears to explain it a bit better, and seems to state a grey material for rear projection!

every day a learning day eh?
Original Poster
JayIce;6892372

for rear projection of a decent size, you are gonna have a lot of wasted … for rear projection of a decent size, you are gonna have a lot of wasted space behind the "screen"I have like 4-5 metres from projector to screen, giving me 150" diagonal widescreen image, you gonna need a looooooong room for the projection space and then to be in front of the screen also.Keystone hasn't seemed to have caused any picture problems what so ever with my setup



Going for around 50" or so. Projector mounted on the floor, pointed at the screen by a mirror. Wasted space = less than 1m.
Original Poster
JayIce;6892590

Translucent Coloured Perspex• 31-37% Light Transmission...I'm no expert, b … Translucent Coloured Perspex• 31-37% Light Transmission...I'm no expert, but I wouldnt of thought that 31-37% light transmission would be enough



Not sure, but seeing 30% of the light when it's at 50" means it should be the same brightness as seeing 100% of the light at around 70". So I'm pretty sure that would be bright enough.
as previously stated also, it seems rear projection material is grey not white!
If your project 45 degrees to the perspex itll work.
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