Discussion of recent posts

[quk@sievers.com (Phil Payne)]

In message <199701201038.CAA32232@cosmoslink.net> "Meron" writes:

>  Bruce, years ago I did this "watt" thing on two type of lights a quad
> setup and a 7" round set up, I went as high as 150 watt (during the days
> that each bulb was $30) and also in three sets of Bosch driving lights and
> one set of Hellas. Std. bulbs were 55/60 watt.
> THERE WAS VERY LITTLE DIFFERENCE!!!!!!!!! (shouting again) this same
> experience was repeated by some of my friends.

Interesting issue.  How sharp were the top-of-beam cutoffs?
 
I'm a bit cramped for time today, what with a high workload and a parents' 
evening at school, but as soon as it's properly dark tomorrow I'll put a 
lightmeter on the top cutoff and see if I can produce a graph of just how sharp 
the Euros are.
 
As a rough benchmark, at ten feet back from the white wall about 1/6th of a 
turn produces detectable movement in the beam position.  The whole transition 
from centre of beam to nothing worth looking at is three or four inches.
 
I suspect that your upper cutoffs are/were much less sharp, and that scattered 
illumination crossing your field of view reduced overall visual contrast.  The 
effect was brighter, but the information content was less.  

--
 Phil Payne
 phil@sievers.com
 Committee Member, UK Audi [ur-]quattro Owners Club