user17016: I need information about video projection. I am looking at a compact projector from China, yg-600. I need a small one that can project a picture that is approx 36" wide from a close distance of approx 20". I don't under the math but the projection ratio is 1.6:1 and aspect ratio is 4:3. Can someone tell me if this will meet what I need? As I think it get 1.6 foot picture from 1 foot away? 
Thanks
John

user14504: Google Projection Throw Calculator, the one on the Christie Website is good. You won't get a 36" size image from 20", with any lens I know of. That would be super wide. 
The shorter your throw / wanting the biggest screen = wider lens. 
Wider Lens = More Expensive typically at least for high quality wides that don't distort. Secondly, wider means typically a hotspot center image... That's why longer throws are preferable. 
I used to have Christie 10K HD Projectors. If you have limited space you can use a projection mirror, or series of mirrors to bounce the image and lengthen the throw. 
It's not uncommon in home theaters, for people who reverse project to mount the projector in the wall sideways; shoot the image down the wall; to a projection mirror which is behind the screen and bounce it back; simply because of space limitations. 
If you use a mirror; your projector will have to have image warping capabilities; at the least keystone correction; H/V flip and preferably depending on if you setup sideways; rotate image. 
As far as mirrors; you want a projection mirror; a regular mirror is made with a sheet of glass on top of the silver backing. This will reflect an image with a 2nd ghost image / making the projected result appear slightly blurry. 
Projection mirrors/Dental Mirrors are mirrors with only the silver, and no protective glass on top. That said, you have to handle them very carefully. 
Hope this helps!

17016: <p>I need information about video projection. I am looking at a compact projector from China, yg-600. I need a small one that can project a picture that is approx 36" wide from a close distance of approx 20". I don't under the math but the projection ratio is 1.6:1 and aspect ratio is 4:3. Can someone tell me if this will meet what I need? As I think it get 1.6 foot picture from 1 foot away? 
Thanks
John</p>
 14504: <p>Google Projection Throw Calculator, the one on the Christie Website is good. You won't get a 36" size image from 20", with any lens I know of. That would be super wide. </p>

<p>The shorter your throw / wanting the biggest screen = wider lens. </p>

<p>Wider Lens = More Expensive typically at least for high quality wides that don't distort. Secondly, wider means typically a hotspot center image... That's why longer throws are preferable. </p>

<p>I used to have Christie 10K HD Projectors. If you have limited space you can use a projection mirror, or series of mirrors to bounce the image and lengthen the throw. </p>

<p>It's not uncommon in home theaters, for people who reverse project to mount the projector in the wall sideways; shoot the image down the wall; to a projection mirror which is behind the screen and bounce it back; simply because of space limitations. </p>

<p>If you use a mirror; your projector will have to have image warping capabilities; at the least keystone correction; H/V flip and preferably depending on if you setup sideways; rotate image. </p>

<p>As far as mirrors; you want a projection mirror; a regular mirror is made with a sheet of glass on top of the silver backing. This will reflect an image with a 2nd ghost image / making the projected result appear slightly blurry. </p>

<p>Projection mirrors/Dental Mirrors are mirrors with only the silver, and no protective glass on top. That said, you have to handle them very carefully. </p>

<p>Hope this helps!</p>
