Some common examples:
1200 K: a candle
2800 K: tungsten lamp (ordinary household bulb), sunrise and sunset
3000 K: studio lamps, photofloods,
5000 K: electronic flash, average daylight. A designation of D50 stands for "Daylight 5000K" and is the most common standard for professional light booths for photography, graphic arts, and other purposes.
6000 K: bright midday sun
7000 K: lightly overcast sky
8000 K: hazy sky
10,000 K: heavily overcast sky
here is some info from usm.edu:
3. What is meant by color temperature?
The Kelvin (K) is the unit of color temperature. 4100K is the brightest, most natural white light similar to that of daytime sunlight, and therefore the HID color temperature used most in the OEM automotive industry. When you look at the light coming directly out of an HID headlight, it possesses a bit of a blue or purple hue which most people recognize as the expensive, elegant look characteristic of HID's. For this reason, some HID kit manufacturers produce 5400K, 6500K, 8000K, etc. bulbs that give an even more distinct blue hue but at the expense of overall light output. For comparison, most halogen headlights have a color temperature around 3200K which gives them a "dingy" yellowish appearance compared to HID's.
Blue light is more fatiguing to the eyes, both to oncoming traffic and to the driver. Oncoming cars will see your lights for only a brief time, but as the driver, you must deal with it for the duration of your drive. The bluer the tint cast on the road and surrounding area, the more quickly your eyes become tired. It's a personal choice and I recognize and respect that some install HID's mostly for the look. However, very blue headlights might get you the wrong kind of attention from law enforcement. Personally, I'd like to benefit from my investment in the way of increased visibility and safety. Be aware that most of the 6500K and higher bulbs are produced by inferior manufacturers to capitalize on the maketability of "the bigger number must be better". Their 8000K bulbs may not measure 8000K. Don't be fooled.
4. What are some good quality brands to look for?
Generally speaking, Philips or Osram (division of Sylvania) kits are recommended because they are the brands used by the major automotive OEM's. They count on quality components because dependability is critical to auto manufacturers. Other brands may use bulbs or ballasts of inferior manufacture that are prone to early failure. Perhaps even more sinister, some kits tout their use of Philips or Osram ballasts while they covertly use cheap bulbs of unknown origin that burn out quickly. So it is a good idea to check the brands you buy. They likely won't be branded by Philips or Osram directly, rather they are usually rebranded by another company. If the seller doesn't specify who makes their components, it is a gamble. A low price is very tempting (believe me, I'm the same way), so my best advice is to solicit opinions and do your research before buying.
here is some info from tbyrne.com:
XENON HID lamps do not have a filament. Instead the light is created by an electrical discharge between two electrodes in an air tight tiny quartz capsule filled with xenon gas, mercury and metal halide salts. This improves durability as road vibrations can cause damage to coil lighting technologies. These light sources also produce a blue-white light that is safer because it is closer to natural daylight. The color temperature is approximately 4200 K compared to 3200 K for halogen. The increased light output from a 35 watt XENON HID lamp is approximately 80% more light then a 55 watt halogen bulb. The XENON HID system will also draw less power from your vehicles electrical system.
Color Temperature is a measurement in Degrees Kelvin that indicates the hue of a specific type of light source. Many people believe the misconception that color temperature is a rating of the brightness of the bulb or HID kit. This belief is completely false. The reality of the matter is that the higher the color temperature, the less useable light output you will obtain. A perfect example would be a black light. This light has a color temperature of approx 12,000k and has almost no useable light or lumens output. Higher K kits such as 7000k, 7500k, etc. have been manufactured for individuals that are more concerned about the actual color output of their lights as opposed to the actual useable light output they produce.
and here is one about the housings:
This section covers special issues that araises when installing HID in Halogen housings
The glass capsule in all hid bulbs more or less have equal size, regardless of manufacturer, rebaser or whether its a OE based (p32-d), rebased or custom base. The length of the glass capsule is around 52mm long and requires a hole in reflector of minimum 15mm and a radius of 13mm where return wire is. This means that kits that are ment to fit all headlamps using a specific halogen type bulb, isn't true in real life. In many cases, they will require more space, in one way or another. Making this space is usually possible, but it might introduce other challenges, such as increased glare, reduced reflector area, or irreversable retrofit.
Is an optical shield always needed?
If you can see the filament in the halogen bulb in your current housing while standing in front of your car, you have to use a shield around the HID bulb. Some HID kits supply a shield. If not, you can also make this shield yourself, but it will take time and you will probably need tools and materials. The reason for needing this shield is that HID bulb gives out around 2-3 times the light compared to a 55W halogen. And that is too bright to look at without sunglasses. All free form headlights (glass is not textured) will need a shield. Reflector based headlights with textured glass have a built in dampening in the glass and you might get away without a shield. Projector type headlamps already have built in shields, so there is no worries there.
Picture below: possible glare reducer by high temp painting bulb
The 2 types of glare shields:
Black painted bulb mask. By painting more than just the tip, the inside temperature of the bulb will increase and life will decrease.
Shields can be made at home as well, just use either a turkey baster or a touch up paint can as donors. Tuch up paint can is the best choice because the end of the cylinder is closed. The turkey baster is open in both ends, unless you are able to still get the long "spout" into your headlight, which depends on the available depth. Picture below shows how the turkey baster version should look like this after cutting and high temp painting.
The flat black high temp paint on the shield will absorb almost all light shining on it and convert it to heat. If heat is a concern for you, use flat gray high temp paint. It will not be as hot, and still give enough light absorbtion and deflection for most applications.
Note that in some cases, glare levels are not possible to bring down to acceptable levels, no matter how good shields you build. Another dead end you can face is that you need to cover up so much of the bulb that the actual gain of using HID is only minor.
Will output be lost by adding shield?
Yes and no. First of all we have to separate between useful and useless light. HID bulbs sends out orange/yellow colors downwards, and that is unwanted light. Light that doesnt go downwards towards the road are definatly useless. There is no point in lighting up trees and walls, blinding other traffic and pedestrians. Adding shield will make your beam look much whiter across the beam.
How close can shield be from bulb glass?
A metal shield directly on the glass will reflect alot of heat back to the bulb, increase bulb temperature and lower bulb life. Choose around 9mm distance from glass. This will also leave enough space for the high voltage return wire. According to manufacturers specs, distance return wire to foreign elements has to be min. 5mm
What materials and adehiesives can be used to fabricate shield?
Expect a bulb temperature of 350-700 degrees Celsius, so stick to metal. Read the Tools and materials section throughly before adding foreign items inside headlight. It is crucial that all items can withstand alot of heat.
How does shield look like from OEM?
These pics is taken from the rear of Mercedes reflector headlamp. It is designed to use a D2R bulb. It shows that the lower 180 degrees of reflector is not in use. This is not uncommon among cars with OEM HID reflector based headlamps. It is the pinstriping on the D2R bulb that will determine alot of cutoff line, not the underbelly shield. A similar shield approach can be taken when converting a single filament halogen based reflector headlamp to HID.
Various Halogen bulbs and HID:
This section will describe the common factors that are found in headlight types that uses various halogen bulbs. This is in many cases too generic and must be read together with the HID upgrade routes.
Depth: H1 capsule is 19mm (44-25) from base of filament to the tip. The same distance on an HID capsule is 23.3 mm (52.5-27.1-2.1). You should leave 5mm distance for the HID bulb return wire. So the required depth is now 28mm (23.3+5). This means that you need 9mm (28-19) extra depth. In a reflector housing it can hit the glare box, if it exist. In a projector housing, it will typically hit the cutoff shield.
(Pics are not in the same scale)
2) Diameter: The hole diameter in the reflector is almost equal (1mm difference). However, the hole has to be made bigger so that the return wire gets its 5mm distance to metal. The return wire is 8.7mm away from the center. Add 5mm and you need 14mm of cutout from the center. Even if you have plastic reflectors this has to be taken into consideration. The reflective material is a chrome substance, and is indeed an electrical conductor.
A standard H3 bulb is 55W and is typically found in less critical applications like aux. lighting. H3 bulbs has been found in some low quality Asian aftermarked headlights. H3 has a lateral mount filament, and HID is only fore and aft, so a result of retrofit is that you will end up with garbage.
H4 is constructed to use the upper portion of the reflector only when low beam filament is on. An internal shield in the H4 bulb will reflect light going downwords towards the upper portion. When you turn high beams on, low beam filament will turn off and high beam filament lights up. It is mounted a little away from the low beam filament, so the beam will hit the road further ahead.
So what happens if you slam an HID bulb in there, correctly mounted in the focal point? Very simply, the entire reflector will be used and even the orange light that normally emits from the lower portion of the HID bulb will be visible on the road. In other words total useless light. By having the HID return wire of the bulb turned down and using an appropiate shield made in stainless steel or aluminum should correct most of it. Both Phoenix MicroLite (Bob) and suvlights.com (Jen L) have premade H4 adapors/shields. Also be aware of possible stray light issues (See above). From time to time Caspers Electronics Inc. (located in Illinois, USA) stock some good quality H4 adapters for D2S bulbs. If you do not see them listed on the site (P/N 103016), inquire per phone. They will not be a plug and play, but it is an excellent basis to make a quality H4 HID retro.
Many kits out there makes you give up high beam. Some people claim that HID will give you the extra light, so high beam becomes unneccsary. This is not true. There are high/low kits you can use - see "aftermarked Bi-Xenon kits" on this page.
base to start of filament: 28.5mm
glass diameter: 17mm
base to tip of glass: 59mm
H7 specs calls for a distance of 25mm from the base flange to the bottom of the filament. D2S/D2R specs call for a distance of 27.1mm from the base flange to the center of the hid capsule. H7 filament is spec'd to be 4.1mm in length, so distance from base flange to filament center is 25 + 4.1/2 or 27.05mm nominally nearly perfect positioning. Hid capsule size is 4.1mm measured along the longitudinal axis, so even that is very nearly identical to the length of the H7 filament. This is if the H7 filament was centered. But it isnt. Its actually off the center axxis by a 1.5mm in downwords direction.
This is originally a 35W bulb for low beam (or fog light). Filament length according to ECE specs is 3.7mm. Other measurements are identical to H9.
H9 is originally a 65W desgined for high beams. Lumes difference up to a 35W HID bulb is the lowest among all halogen bulbs, so this will normally make a good retro. H9 have a 27mm distance from reference plane to bottom of filament.
H11 (55W) is designed for headlamps. Filament length according to ECE specs is 4.5mm. Other measurements are identical to H9.
H13 (or 9008) HID
Will hit marked in the first years of 2000-2010. Its a 55W/65W dual filament bulb for headlamps.
Like H3, 9004 have a lateral filament wich current longitunal HID bulbs are not compatibe with. Dont wait for any lateral HID bulbs either - they are not going to show up on the marked.
Is generally a good fitment for HID capsule, it has to sit 31.5 - 27.1 => 4.4mm backwords:
In 99% of all housings that utilises 9007, you will never be able to get OEM quality ligthing with an HID upgrade kit. Theoretically H4 has a better success rate than 9007. At least H4 is designed to use top part of reflector only, which helps when you want to decrease light above cutoff. High and low beam are selected by using 2 different filaments above each other. Low beam filament sits above high beam filament. 9007 based reflectors utilises most of the reflector area in both modes. This means that a shield is needed to block bottom part of reflector to hinder yellow light to reach the road. So far so good. But what about the increase light above the bright oval? That will be totally overfilled with glare. Also, filament length is 5mm. The HID filament is 4.2mm. That will make an HID upgraded 9007 have a smaller, distorted and partially intense pattern with possible blacked out center. Outside that you will notice the increased glare.
Conclusion: If you are able to (do or pay for) a custom job by using stock housings, it will take so many hours to end up with an half decent job that you would be better off taking a part time job and buy OEM HID houses, if they are available. They are available for 98+ Ford F150 and Expedition (directly off of Sylvanias site). Even if you retrofit projectors from a well functioning setup (see OEM HID overview page), into your headlights or create your own bracket, it would still be worth it, qualitywise. Also see the discussion regarding loss of high beam in the H4 section.
Remaining Halogen Bulb Specifications:
Back to HID headlamp menu
to see the pictures and graphics for this last piece I got it at this web site: http://faqlight.carpassion.info/special-topics.htm