- The inside of the box coming out of the TV must be painted matt black. If not any other colour will reflect that colour light at different angles through the lens, and cause a blurry picture. Also this happens if the black is shiney black not matt.

- The lens has to be bumby side facing the screen, otherwise you will find that the focus at the center is good and the focus at the edges is bad.

- The size of the hole is important as well, because the bigger the hole the blurrier and lighter the picture and the smaller the hole is , the sharper and darker the picture. the hole on my LCD projector is 1.8 inches in diameter purely because the 750w metal halide bulb produces enough light to keep the picture bright with such a small aperture. however you will need to experiment with the size of the hole.

- Make sure your TV's contrast is set to full and the brightness is set quite high (I know this might sound like i am teaching you to suck sour eggs, but its surprising how many people don't do this)

- The focal length of the average lens is 30cm so the lens should be around 30cm from the TV screen.

- And lastly the surface you project onto makes a big difference to the final picture. A wall is white but doesn't reflect as much as a proper screen, also the reflection goes in lots of different directions and blacks look dark grey. A grey screen increases the percieved contrast as black is darker but needs a pitch black room to work.