Hella Headlight and Auxiliary Lamp Beam Patterns

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

A 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).

A 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.

A 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.