On 10/05/2021 17:47, Daniel Bowen wrote:
> Notice the Z/B class LED destos sometimes randomly show up as readable. It's a bit of a battle to slow down the shutter speed to make them (and the E-class) destos readable in photos without getting too much blur in the photo.


All the digital displays are 'intermittent'.

Like TV they take advantage of our persistence of vision to show displays briefly and let our brains sort it out.

The difference between then type destinations on the Z, A and B trams and those on the Es is that one (Z etc) shows the whole destination in a scan, then goes blank before showing it again while the E's use 'interlaced scanning' like traditional TV showing half the lines in one period then the other half in the following period.

So Z,A,B trams show the whole destination or nothing when the shutter is open, while E's show just half the destination (in stripes) while the shutter is open at normal shutter speeds.

Examples attached ...

Either type shows the whole destination if the shutter speed is less than 1/60 sec.

Mal Rowe - who once taught about TV