On Sat, 08 Feb 2020 11:00:13 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Dave W wrote:
That entirely depends on the type of headlight. Projector types - with a
bulls eye in front of the bulb - are very tolerant of bulb type.
Tungsten, HID or LED all give a similar and well controlled beam pattern.

You'll see that demonstrated on U Tube if you're interested.

I would dispute that - some cars give a dazzling blue side spill due
to the non-achromatic lens.

If it gives a dazzling side spill, that will show up in the beam pattern?

Most of these projector lights produce a spike of light to the left which
lights up the side of the road way beyond the range of the main part of
the dip. If a car is parked on the wrong side of the road, headlights on,
oncoming cars get the full force of that spike.
--

I was talking about oncoming cars. The main beam may be dipped, but I
get the blue spill just as they're passing.
--
Dave W