I found only one page with "lights source" "plate." I think phpBB doesn't do quote searches. Instead, I use patience and also use the browser's search function.
...when the light source
is 45 degrees...
...that will change to a mount plate
- again, ...viewtopic.php?f=1&t=262
phpBB has its limitations but I think their search engine is okay and pretty fast now. Years ago, their search function was awful. But now, I can't wait to use it.