Actually, none of the automatic lenses on the market today will allow
damage to your eyes even if they do not darken fast enough or properly.
The early auto-darken lenses were virtually transparent to UV until they
darkened. Speed of transition became the code of the day, but the
solution was to tint the un-activated lens and use UV filtering
materials as part of the lens. Today's lens' speed reduces or eliminates
the "dazzle" of the arc strike, but even if the activation section of
the lens is blocked so that it doesn't activate you don't get flash
(sunburn of the retina).

"Rich S." wrote:

"Todd Pattist" wrote in message
...

It's not speed, it's brightness. If you can squeeze enough
energy into the 1/20000 second, you can do the eye damage
before the glass darkens. Lasers can make high energy
femtosecond pulses. Welders can't.

Todd............

Jes' kidding about the speed - but you knew that. )

But - I didn't know what other quality might be responsible for retinal
damage - color, frequency, brightness or penetration of the shield.

Thanks,
Rich

--
Bruce A. Frank, Editor "Ford 3.8/4.2L Engine and V-6 STOL
Homebuilt Aircraft Newsletter"
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| on all aspects of alternative |
| engines and homebuilt aircraft.|
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0 0 TIG welding

While trying to find the time to finish mine.