"Sam Goldwasser" wrote in message
...
"William Sommerwerck" writes:

One possible source of moire patterns is the use of a 625-line tube
in a 525-line set, or vice-versa.

Huh? A 625line tube? Perhaps you should clarify.

This isn't a joke.

Think of the way a shadow mask has hundreds of thousands of tiny holes,
spaced at some particular pitch. Now imagine those whole "interfering" with
the scanning lines in the image, producing a moire.

I first learned of this about 25 years ago, when I viewed the then-new
Proton TVs. Proton was using CRTs with a dot-pitch suitable for a 625-line
system in 525-line TVs, to get better horizontal resolution. Unfortunately,
this sometimes produced moire patterns.