Wrong size screen

[dedwards96]

Hi,

 

For our upcoming show, we require two projection screens. One is permanently installed so we will have no problems with that one, the other is a small old NEC projector shooting onto a 60" x 45" screen about 20' away. The problem is that the projector does not have a fantastic zoom function so the projected image is about 3x larger than desired.

 

What is the best way to get the image to fit without moving the screen or projector?

 

Thanks, Dan.

[Ynot]

Without moving either the screen or source (projector) the only way to change the image size is to change the lens. If the machine doesn't have interchangeable lenses (many smaller units do not) then your flat out of luck.

[jason5d]

Project an image that's 3x smaller. The projector may

have a zoom function that might help you do this,

otherwise use software.

[Ynot]

Project an image that's 3x smaller.

Is that really going to help?

 

I would read 'old, small' projector as a machine with limited capabilities and power output.

 

So sending it a picture that is a 1/3 of the overall size is going to mean the actual picture brightness is going to be considerably less bright than the full sized pic with a suitable zoom lens.

 

And as with many low-end projectors, it will also mean that there will be a lovely bright border around the main image that's twice the size in area of the desired pic... Because few of those low end machines will project black as anything other than a mid to light grey...

 

I can't see that reducing the image in software in this situation would be of any use whatsoever...

[Shez]

Project an image that's 3x smaller.

But bear in mind that by doing so, you're wasting most of the resolution and brightness of the projector. You'll also be projecting a small amount of light on to the set around the outside of the screen; that may or may not be a problem depending on what colour it is and what the ambient light levels are like.

 

Edit: beaten by Ynot

[dedwards96]

Project an image that's 3x smaller.

But bear in mind that by doing so, you're wasting most of the resolution and brightness of the projector. You'll also be projecting a small amount of light on to the set around the outside of the screen; that may or may not be a problem depending on what colour it is and what the ambient light levels are like.

 

Edit: beaten by Ynot

 

This was my original thought. We'll try it and see how it looks but I'm not holding out much hope!

 

Thanks again.

[Bazz339]

I would be a little wary of blocking a large portion of light from the projector for a long period of time as you would be if you are projecting a large black border. It may cause excessive heat build up and risk damage.

[LXbydesign]

Actually - a low tech way of doing it without any particular software is to simply load the video onto a power-point slide (on a plain black background) and then your able to crop the edges to fit the screen by shifting the video around within the slide to get the right position.

 

Hope that's clear. That's how Ive overcome exactly the same problem.

[Habu]

My photographer friend has used camera lens to make image bigger. There wasn't any streched corners or anything in the picture. He just somehow taped lens in front of projector. I'm not a photographer but is it possible to make image smaller with some kind of camera lens?

[Ynot]

Actually - a low tech way of doing it without any particular software is to simply load the video onto a power-point slide (on a plain black background) and then your able to crop the edges to fit the screen by shifting the video around within the slide to get the right position.

 

Hope that's clear. That's how Ive overcome exactly the same problem.

I think you're missing the crux of what I'd see as a flaw in that plan - as described above....

 

No matter how you reduce the image on the PC to fit the image onto the desired projection screen, you will still be left with a border all round that image. And few of the smaller machines will be able to project black particularly well, so that border will still be projected as a dirty grey, thus spilling all round the screen and onto the set/stage/prosc/whatever.

 

Add to that the other thing we've mentioned already in that you're also losing maybe 2/3 of the projector's available lumens output on the actual image you want, and it all really seems a lot of pointless exercising with very poor potential results....

[David Lee]

Best options are move the projector or change the lens, all other option are horrible bodges.