E-code low beam headlamps have
a wide beam
that lights
the road from
side to side.
They are useful
at 300-400
feet. There
is a sharp
horizontal
transition
from dark to
light about
in about 2" vertically
at about 25
feet. A wedge
of light on
the right side
lights up roadside
signs. On low
beam you can
expect about
four times
as much light
on the road
as a standard
sealed beam
and twice as
much on high
beam. Because
of the tight
beam control,
these lamps
can be aimed
very accurately
which facilitates
the use of
upgraded bulbs
without offending
oncoming traffic.
E-code high
beam headlamps
focus their
light energy
far down the
road - little
light is wasted
lighting up
the side of
the road near
the car. These
lamps are not
certified for
use on public
highways in
the US and
are sold for
off road and
racing purposes
only. |
  Vision
Plus headlamps have a similar beam to the E-code lamps with the following differences; 1) They have the three aiming lugs on the face of the lens to allow
machine aiming. 2) They have a portion of their light shining up, as required by
DOT, to light up overhead signs. This part of the beams makes these lamp
unsuitable for upgraded bulbs. 3) The have the DOT symbol molded into the face
of the lens and are legal in all 50 states. 4) They come packaged with a 60/55
watt HB2 bulb to meet the maximum wattage allowed by DOT. Vision Plus Lamps are
only available in 7 inch round and 200mm rectangular lamps. |
 Eurobeam or Driving beams are used with your high beams. The pattern is conical, flattened at the top and bottom and about 110-120 degrees wide. Useful at 2000-2500 feet. DOT requires that driving lights be wired so that they can only come on with your high beams and go off with your low beams. |
 A Pencil Beam is just that - a very long, narrow beam - very specialized. Used for rally in conjunction with other lamps and used for desert racing but with at least a dozen on a vehicle. Will light a reflector at two miles. Not useful unless you have a lot of them. DOT requires that pencil driving lights be wired so that they go off when your low beams come on. |
 A Fog Pattern is very wide and very flat. Maybe 170 Degrees wide and only a couple feet high. It's only good for a couple hundred feet by design. It's purpose is to light up the road in bad weather without reflecting light off the snow/fog/rain back into the driver's eyes. A clear fog lamp is often used to fill in the area the low beams don't get to light up close to the car and the sides of the road. Some people like amber fog lamps because they claim that the yellow light causes less eye strain in bad weather and gives you a little more contrast. |
 A Cornering Pattern is a flood light - good for only several hundred feet - also very specialized. Used in rally in conjunction with other lamps. Good for offroad use if all your offroad is rock crawling or very slow travel. DOT requires that Cornering lights be wired so that they go off when your low beams come on. |
A City Light or
Position Light
is a European thing.
They are similar
to daytime running
lights in the US.
They are simply
a 5 watt bulb that
lights up the reflector
to make you more
visible to other
traffic, but creates
no appreciable
illumination. In
the big cities
of Europe the street
lighting is excellent
and cars are not
permitted to use
even their low
beams, in order
to control light
pollution. Several
new types of city
lamps have been
introduced including
Celis "Angel Eye" rings
and LEDs. |
Lamp Construction Types and Factors |
 Parabolic lamp
has a parabolic reflector. The
reflector collects the light and the lens does the beam control.
These lamp typically collect about 27% of the light created
by the light source (bulb). |
 Free
Form lamp
has a reflector
which is not
a parabola,
but is a computer
designed complex
shape. Hella
uses
over
50,000
points
to
define
this
shape.
The
reflector
collects
the
light and shapes
the
beam
while
the
clear
lens
simply
keeps
the
dirt
out.
The
lack
of
fluting
on
the
lens
reduces
defraction
of
the
light
and
increases
output.
Free
form
lamps
typically
collect
about
45%
of
the
light
available. |
 Projector,
or DE lamp has a free form reflector
with a large surface area that collects a lot of light while
having a small overall diameter. Unfortunately, the lens is
so convoluted that it takes a special projector lens to collect
the light get it going in the right direction. These lamps
collect as much as 52% of the light the bulb makes. |
Size - As in most things, bigger is better. A larger reflector will collect more of the available light from a given bulb. In addition, because of the larger size, you can increase the wattage of the bulb and better dissipate the heat generated.
|
Shape- The nature of light waves is circular when near the source - the further from the light source, the more linear they appear. When installed in a lamp, the light waves from a bulb appear circular and are much easier to control with circular shaping mechanisms - Round lamps typically generate better light patterns than rectangular or square lamps.
|
Manufacturer - If you haven't heard of the manufacturer, there is probably a reason. There are some truly horrible projector lamps out there. Recently, a supplier was fined over a million dollars for selling a projector lamp as meeting the DOT standard, which it didn't. The DOT standard is easy to meet, sealed beams meet it. |