I have the prefect wall in my basement for a 16:9 image. the wall is 12 wide and 7 ft tall. If my calculations are correct i can fit a 144in x 81in image! The problem is a 4:3 image would run onto the floor and celling... I calculated a good 4:3 size would be 108in x 81in (notice width is the only change). I've attached a picture of what i'm trying to do.

Click to view attachment

What do I have to move to change the image size? I was reading about the box inside the box design, but how much movement do i need to change the image this much?

I'd like to put my projector about 14 feet back from the screen whats a good layout for the inside stuff, how far apart should the lens be???

Thanks for helping a newbie!!

Ok maybe I'm not being clear or I'm way off in left field...

I was thinking of designing my box with a dual focus system. basically have a box with in a box with in a box (two inner boxes). I'd like to have a way to change the image size from 144x108 to 108x81

- the 144x108 will fit a 16:9 image with the black bars on the floor and celling (144x81 viewable)
- the 108x81 will fit the 4:3 image all on the wall

The idea is the main box is mounted and never moved. the first inner box is setup to adjust the screen from the 144x108 to 108x81 position. then the next inner box would be your normal fine tune focusing box. does this sound like it can be done? I was wondering if any of the other lens would have to move too? I can draw up some pictures tonight if that would help.

Can someone help me with the distances of each lens i'd need for both image sizes? I try the calculator tool but i don't think i did it right...


Thanks for the help!!

To do what you are describing you would need a projection lens with a variable focal length or 2 projection lenses with different focal lengths that you would switch between.

Probably an easier way would be to build your projector using a 16:9 widescreen panel that will accept a 4:3 input also. Just an idea.

David.

Edit: Just wanted to be a little more clear. To change the projected image size you have to change one of 3 things. Either the source image size, the focal length of the projection lens, or the distance from the projector to the screen.

I guess I should say there are other options. For example using powerstrip to change the size of the 4:3 image on your panel. Really anything you can think of that changes one of the 3 factors mentioned above should be workable.

thanks for the reply! I already have my panel its a 15" 4:3.

thats funny i was just reading about powerstrip after i posted the last message

I'm thinking i'll go with a fixed 16:9 image... but will this skew anything? I plan to use a HTPC with a ATI all-in-wonder then running xbox to the RCA in's on the card, will the image be messed up when running the custom res? I read that ATI has problems with that software...

thanks!!

I don't remember where right now but I read in a thread here that someone had to use driver version 5.0 or older for the ATI to get it to work right. You should be able to find it in a search for powerstrip. As for any other problems you might have, your best bet is to try it and see what happens.

David.

xiopod,

what you want is what I am doing now. you can use powerstrip to resize the desktop to 1024x576 (16:9), then 4:3 material will have a resolution of 768x576. If you want 1024x768 resolution for 4:3 material, the easiest thing to do is make the PJ portable so you can change it's location depending on what format you are using. If you plan on doing gaming on your PJ, just beware that PC games will not be able to run in a 768x576 resolution, so it will default to running the entire 1024x768 pixels, and will not fit on the screen. I would also suggest connecting xbox via s-video for improved quality over the composite (RCA) connection. I think catalyst v5.1 is the lastest release you can use with powerstrip, and it appears to only work on VGA, except I did get a 17" monitor (1280x1024) to work properly on DVI using cataylst v5.13, but I don't even see that version of the driver on their site anymore... perhaps they rolled it into the newly released v6.1... haven't fooled around with it lately.

good luck.

cheers,
gs