On below picture, you can see the dependence of horizontal resolution on transmission time of one picture element. Shorter time of transmission need more band width and better signal to noise rate. Longer times consumes narrower band width and modes are more resistant to noise.
Resolution Test Pattern
Martin M2 (±220µs)
Robot 36 Color (±280µs)
Martin M1 (±450µs)
MP115 (±680µs)
Scottie DX (±980µs)