Re: Measuring Distance by Headlamp Luminosity

[raf40@oes.amdahl.com (Richard Funnell)]

>Al said:
>
>>Not THREE seconds later, an old late 50's Chevy went past in the
>>other lane!!  The headlights were so dim that I suspect he may have
>>been running off his battery to get home.
>>
>>The point: his lights fooled me.  Until then, I didn't realize that
>>slightly dim lights could look MUCH farther away than they were.  And
>>it damn near got him and me killed in a 60+ MPH head-on, because he
>>looked at a leat a mile farther away then he actually was!"
>
>I'm not an expert, but I know you can't measure distance on the basis of
>brightness alone.  This is a well established fact in optics.  If you
>had
>hit the Chevy it would have been entirely your fault for using this
>false
>assumption.

---snip---

If a car is coming straight at you at night, it's not easy to tell how fast
it's approaching.  I suspect most of us use brightness, at least
subconciously, as a key indicator.

>Greg Koehler
>Kirkland, WA
>'90 80Q


Richard Funnell,
San Jose, California
'83 urQ
'87 560 SL