Sony 1270Q CRT Setup And Operation Manual page 4

Scan Line
Scan Line
Overlap
Some people prefer this "soft" picture, but I have found that 600P-666P
looks very sharp and 3 dimensional. Keep in mind that when displaying 16:9
material, you are using a smaller phosphor area than a 4:3 image and
therefore can resolve 25% less scan lines.
With my projector setup the best that I have been able to do, it can resolve
666 scan lines or 666P. I can see scan lines if I am less than about 6 feet
away from the screen and the picture is very sharp. I have run at 540P,
600P, 666P, 720P and 768P, with 666P being the highest resolution I can
make it resolve. There has been some discussion on the AVS Forum which
gives a mathematical solution to this exact topic with the verdict being about
600 to 700 scan lines being the maximum(in 16:9 mode). This depends on a
lot of things, one being how close the projector is to the screen (this is
covered later).
Ideal Situation (0 overlap, 0 gaps)
Excessive Scan lines (overlap)