QUOTE(Bazil @ Jul 9 2004, 07:14 AM)

Here is a quick explanation of why Depth of Field occurs
The reason why a smaller apeture creates a larger depth of field is because the smaller the apeture, the more concentrated the light is as it goes through acthe hole... A pin hole camera has a huge depth of field because the hole is tiny... A camera with an apeture of infinate "smallness" (really really really really really really really really really really small ) will have everything it picks up, perfectly in focus (stuff that's miles away (if you could see that far) would all be in focus.
It works like this because when the light enters the hole (apeture) it has less option to not fall on the ccd/point of focus and therefore is concentrated on exactly the right place. However, if a camera is setup with f2.8, the light can shine onto otherparts (inside the camera) without hitting the CCD... To compensate, you stick a lens infront of the hole and this therefore helps to perfect the focus, but, as we all know (from using cameras and our understanding of focus) it's not perfect and thus depth of field is created.
I hope I worded this alright! I'm sorry if some of you didn't understand, but that's pretty much the jyst.
Bazil
Don't worry I'm only reposting this because it's a pretty informative quote. From now on i won't bother though.