Date: Wed, 24 Apr 2013 08:19:21 -0700
Reply-To: Al Knoll <anasasi@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Al Knoll <anasasi@GMAIL.COM>
Subject: Re: Headlights
In-Reply-To: <9D70B4C8-CDEB-4D82-BDCE-699DFE8B2CF6@aol.com>
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Like pouring coffee into a drunk. The headlight optics stock on the
rectangulars is horrid. Add more lumens (watts is a measure of the power
the capsules aka bulbs draw) and voila a wide awake drunk. Still awful but
now really awful.
Pattern: the shape of the illuminated area
Cutoff: the vertical component of the pattern
For an ideal system the pattern covers just what you want to see, not the
oncoming drivers windscreen, with excellent road side illumination for the
occasional suicidal deer or other critter.
The sharp cutoff european LHD standard is almost perfect for the
application. Either in bentstraits fashionable rectangular lenses or the
7" sharp cutoff round lenses. These implementations if properly aimed
don't dazzle the bobbies and are an easy upgrade.
The almost perfect comment is in regard to the inability to have both the
ideally
aimed high beam and the ideally aimed sharp cutoff low beam. Has to do
with the optics of the lenses, not a changeable feature. The relationship
between the COB center of beam between high and low is a compromise on
installations where the mounting center of the lens is too high
(vanagon). For normal driving one would like the cutoff slightly
depressed from the vertical so as to take maximum advantage of that near
perfect pattern, in town and on the road. Unfortunately that raises the
high beam pattern to illuminate the trees and not the road. Great for
jacklighting owls not so great for ordinary driving.
The ideal system has compensation built into the reflector itself. The
independently aimable low and high beams allow virtually perfect pattern
aiming. Not so fast there bunkie! Stop the drooling and listen up. The
rectangular E-codes of bentbtst8 lore are a pittance compared with the
ultimate. A used pair of Marchal Ampilux 7" can often be found at a
bargain basement price of say 300 to 500 dollars. These can be
independently aimed and no they don't use H4s but rather two capsules per
reflector to permit the independent aiming. As close to St. Francis as
you can get for ordinary money.
Aim them suckers frequently, that cutoff pattern is what you crave, ideally
aimed, and properly powered.
Brazil makes an h4-h1 lens thingy that fits early busses, might be
adaptable for vanagons.
'Nother solution is designing a four lens system that uses the larger
rectangular h4 lenses in all four spots. An artesian I seen oncet had em.
Let there be light...
Pensionerd (rumours of my capture in afghanistan were overated)