You just experiment. Some screens have buttons that either brighten, dim or reverse the video; if you started on a black background, such a button would change the background to white and show the print in dark. Every screen is different. Try and try again. Every display and every optacon will be different. As I've said, I usually don't need a CRT lens because when I've looked at Windows screens, I've seen a white or light background with dark print, like reading a book, so I've used the regular optacon lens. But when Windows dies, a CRT lens is essential because the lower-level install reverts back to a DOS screen with green on black. Mary to view the list archives, go to: www.freelists.org/archives/optacon-l To unsubscribe at any time, just send a message to: optacon-l-request@xxxxxxxxxxxxx with the word "unsubscribe" (without the quotes) in the message subject. Tell your friends about the list. They can subscribe by sending a message to: optacon-l-request@xxxxxxxxxxxxx with the word "subscribe" (without the quotes) in the message subject.