Chris explained on 15/08/2018 :
Been thinking it's about time I got one of those auto-darkening helmets.
Just a bit concerned about that initial flash that's supposed to trigger
the auto-darken feature. I can't see how it can be fast enough to
eliminate exposure to that first bright flash. Anyone used one? Comments
on their efficacy?

I bought one around ten years ago and they make it so much easier. I
always struggled to get the rod into place, then drop the helmet. Now I
can see, to get the rod spot on. I've not noticed any delay in
darkening, but my helmet has two setting pots which I have never
bothered to experiment with.

Even supposing there is some delay, the slight exposure has to be an
improvement on the accidental flash I would sometimes get whilst trying
to align the rod to the job.