On 29/09/2017 07:23, Brian Gaff wrote:
Yes they can. I think it has something to do with the fact they do not
actually have any persistence of emission like most tungsten lamps would or
like the coating on many discharge lamps.
I think you would need to be very unlucky to get the strobe speed so near
a rotation speed that it almost stood still though.

It is because a lot of LED torches use a high efficiency switched mode
current drive power supply. A side effect is that the LED brightness is
modulated at a moderately high frequency.

You can see it too on car brake lights and pelican crossings in your
peripheral vision (the strobe rate on them is a bit low for my taste).

--
Regards,
Martin Brown