March 24th, 2007 01:42 AM
Flashlight Buying Guide
This was taken for the Cabelas site and there is no Copyright posted with it so I'll put it here. It's very complete and informative.
All credit to Frank Ross
Flashlight and Headlamp Buyer's Guide
By: Frank Ross
Not too long ago, buying a flashlight was a simple process, mainly because there weren't that many choices. The most challenging decision was how many batteries did you want to use. Traditionally, you had the option of selecting a large, rectangular 6-volt battery for extra power or units with 2, 4 or 6 D-cell batteries.
Today, the choices are so wide and varied that it is daunting to look through Cabela's catalog or here at cabelas.com, where there are over 50 different models, sizes and styles to choose from. Should you buy a light with a traditional tungsten bulb, or how about xenon, high-pressure xenon, halogen, LEDs or even Krypton?
Further confusion arises when you realize that flashlights and headlamps are measured in a number of different ways and the output of any light is affected by the quality of the reflector, amount of battery power available, quality of the bezel and the output of the bulb or LED. (I'll explain these factors in detail.)
While all elements of a portable lighting device are important, none have as much impact on the total picture as the bulb or LED that does the hard work - making light. Tremendous advances have been made in light technology in just the past five years, but the real juggernaut has come in just the past two years in terms of applied technology to products when can use. When you consider the technological advances in flashlights and headlamps, it's a lot like comparing the sound quality of a digitally recorded CD to that of the historic vinyl LP. Today, highly engineered, machine-tooled frames, computer designed reflectors, space-age bezels and advancement in bulb technology make portable lighting almost as remarkable as Luke Skywalker's light saber.
Originally, incandescent bulbs had a tungsten filament surrounded by a vacuum inside a glass tube. Incandescent literally means to give off light as a result of being heated. The most salient limitation of incandescent bulbs is the output spectrum, which has a long sweeping tail that falls on the red side, extending well into the infrared. With traditional incandescent lamps, the majority of the output actually falls in the infrared and ends up as just heat. In fact, with standard incandescent bulbs only about 10% of the consumed electrical energy is converted into useful light, or light that is in the visible part of the spectrum. If tungsten could be operated a few degrees hotter it would produce much more light. Unfortunately, tungsten is operated as close to the melting point as possible, and even a few more degrees would burn the filament up very quickly.
Longer-life tungsten bulbs achieve their increased lifespan with heavier filaments that will handle more heat, but produce less light.
The next step in the evolution of incandescent bulbs was substituting gases for the vacuum. Argon/nitrogen were the initial gas used, but it was discovered that krypton conducts heat less than argon, and xenon conducts even less heat than krypton. In addition, the larger atoms of krypton and xenon are better for bouncing evaporated tungsten atoms back onto the filament than the smaller atoms of argon and nitrogen. All of the bulbs listed below are technologically superior to the standard tungsten bulb, and with the exception of High Pressure Xenon bulbs, all have tungsten filaments that will last much longer, but eventually burn out and have to be replaced. Filaments are fragile and subject to breaking when jarred severely or dropped, especially when burning. The down side to bulbs is that they have a limited life, more dominant shadows and have a very high rate of power consumption.
Halogen bulbs are made of glass filled with a small amount of halogen gas. When standard filament is charged with current small particles of tungsten evaporates and is collected on the inside of the bulb's glass surface. When a trace amount of Halogen is added to the bulb, a chemical reaction takes place, which removes the tungsten from the wall of the glass and deposits it back onto the filament, extending the life of the bulb.
In order for that beneficial chemical reaction to take place, the filament needs to be hotter than for standard incandescent bulbs. That a hotter filament produces a whiter light and is more efficient -more lumens per watt of consumed power. Halogen bulbs offer energy savings compared to conventional incandescent light bulbs, but fall short of xenon bulbs. The average lifespan of halogen a bulb is 2,500 hours.
Krypton bulbs are made of glass and filled with krypton gas. This technology uses a filament, but produces double the average life of conventional tungsten light bulbs with an average life up to 2,000 hours.
Xenon bulbs are made of glass and filled with metal salts and a mixture of noble (non-reactive) gases including xenon, which produce a clear, white light. The average life span of xenon bulbs is 5,000 hours. Xenon bulbs produce low levels of infrared and ultra-violet radiation while emitting twice the amount of light of a halogen bulb. Xenon is very efficient, when compared to halogen, producing twice the light while consuming half the power.
High Pressure Xenon bulbs are made of thicker glass containing metal salts and a mixture of noble (non-reactive) gases including high-pressure xenon gas pressurized to several atmospheres. HP xenon bulbs are typically about half the size of xenon bulbs and operate on a gas discharge principle. An arc of light is created between two electrodes in a glass tube filled with gas. Xenon gas bulbs emit a clear, white light with an average lifespan of about 5,000 hours. HP xenon bulbs produce low levels of infrared and ultra-violet radiation while producing twice the amount of light of a halogen bulb, and consuming only half the power.
Once Light Emitting Diodes (LEDs) were invented, a lot of changes started happening, almost at the speed of light. LEDs are basically a light bulb without a filament to burn out, and since they are very efficient at creating light without heat loss, they don't get hot. The LEDs longevity is further enhanced by its construction. An unbreakable, crystal clear, solid resin encases each LED and makes it nearly indestructible. The drawback to LEDs is their limited output for projecting over a great distance.
All LEDs are environmentally friendly since they have no waste or mercury. All LEDs operate at low temperatures, which make them safe to touch. LEDs have an average lifespan of 100,000 hours of continuous or cumulative use, operate on low voltage DC power, and produce no UV light. Light output of LEDs are measured in lumens; energy input to a lamp is measured in watts. The efficiency of a lamp is expressed as lumens per watt.
NICHIA 5 mm LEDs produce 2-3 lumens of light for each LED. LEDs provide instant illumination; produce low heat and no UV light. LEDs are also more energy efficient than conventional incandescent light bulbs because most of the energy is turned directly into light; however, single LEDs do not create a significant amount of light. Most sophisticated designs today use clusters of LEDs to increase a unit's output and LUXEON LEDs accomplish this task very nicely.
LUXEON 1-Watt LEDs produce up to 25-30 lumens and provide 10 times the lumens of standard NICHIA LEDs.
LUXEON 3-Watt LEDs have an output of up to 75-80 lumens, or three times the lumens of Luxeon 1 watt LEDs and 25 times the lumens of standard NICHIA LEDs.
LUXEON 5-Watt LEDs have an output of up to 120 lumens, provide four times the lumens of LUXEON 1 watt LEDs and 50 times the lumens of standard NICHIA LEDs, the equivalent of 50, 5mm LEDs.
Beyond the bulb/LED factor, when you break down the issues involved in selecting an illumination device, there are only a few factors that are relevant.
Size can be a factor, especially with the magnum output and size of the Thor 10-million candlepower spotlight. While it has phenomenal output, putting this unit in a backpack would just about fill it up, not to mention the weight. Choose a light that will be comfortable to carry if you will be traveling on foot. Generally, the power source dictates the design and size as well as weight of an illumination device. While five-D-cell lights are impressive in length, their strong suit is that of impromptu Billy club, when weight, diameter and length are most advantageous.
Brightness is always a factor, especially if you are going to be illuminating objects at great distances or need to see items in great detail.
operation time as well. Available and sustainable power is a critical factor if you are going to a remote region where replacement batteries or access to recharging current will be limited or nonexistent. Power is particularly important with some of the newer technologies that require high output power sources such as nickel-cadmium, lithium or lithium-ion batteries.
Construction is a key factor if you tend to drop things or use your light in rain, sleet or snow. The most rugged flashlights are made of machined aluminum with O-rings to keep out moisture. You'll find that anodized finishes are very hard and difficult to scratch under normal use, which will keep your light looking new for many years.
Once you start sorting out these factors, you'll quickly find that bulb/LED choice will play a major role in all of the above. Here are some considerations in terms of output, lifespan and power consumption.
"How bright is that light?" is a question that has been answered in many ways. The problem with scientists and engineers is that they quantify everything in a number of different ways and comparing the two is often baffling to the average layman. Books have been written on the issues involved with the measurement and comparison of light and light sources. These voluminous tomes are peppered with terms like lumen, candela, lux, emittance, light power flux, luminous intensity, incident flux and diffuse reflected flux. Hopefully, these basic descriptions will shed enough light on the subject to help you through the process.
Candlepower is an obsolete unit of illumination, equivalent to one lumen ft2. And here comes the kicker! A candlepower as a unit of measure is not the same as a foot-candle. A candlepower is a measurement of the light at the source, not at the object you light up.
The most common terms used to evaluate a light's capacity are candlepower and lumens. Lumens are the easiest to understand, and also the most regulated by the International System of Measurements. In scientific jargon, one lumen is the unit of luminous flux equal to the amount of light given out through a solid angle by a source of one candela intensity, radiating equally in all directions. Simply put, a measure of the output of the light source without the aid of a reflector.
The problem with trying to compare candlepower with lumens or any other measurement is that you don't know how the candlepower rating was determined. Peak beam candlepower is a measurement of the brightest spot in a focused beam, and not the true output of the light source. The most important issue is that regardless of the rating system, the effectiveness of a light source depends upon the perception of the human eye and is therefore subjective and relative to each individuals ability to see the full spectrum of light. Because of this human factor, perhaps the most effective way to compare lights is to turn it on and compare it to another and see what you think for yourself.
As noted above, the quality of a reflector can have a tremendous impact on both a light's brightness and the beam it projects. Manufacturers have found that one of the easiest ways to boost a light's output is to enhance the surface directly behind the bulb. With the advent of computer design and space age materials, reflectors have come a long way. You'll find a number of types in terms of both design and material. In some instances you may want a spotlight that throws a very narrow beam for a great distance, and at other times you may want a floodlight that illuminates a wide area equally and brightly.
Parabolic reflectors are computer designed to maximize the angle of reflectivity while the surface is coated to magnify existing light and project it to its fullest potential. The result is a beam that appears much brighter when compared to a light with the same lumen output, but without a highly engineered reflector. Photon-tube reflectors deliver an extra-wide and focused beam at the same time.
One shortcoming of traditional flashlights was their highly focused beams and bright only output. When you left the campfire and ventured into the dark woods, the bright beam was narrowly focused and due to its brightness it made the surrounding woods even darker because your eyes couldn't adjust. LEDs produce a softer light, and when you use a light that spreads the beam even wider, the affect is more like that of a fluorescent light that gently illuminates a wider area.
Reflectors can improve the overall brightness of a light or focus the beam in a very narrow area, but with some lights today, the strategic placement of LEDs in combination with incandescent bulbs gives you the ability to do both.
A bezel is just a fancy word for the transparent material that allows the light to shine through and keeps moisture out. Glass or plastic were the old world options and neither performed well. Glass was easily broken and plastic was easily scratched, became discolored with time or became dislodged with very little pressure. Today's high-tech models feature rugged materials that are clearer, harder to scratch and nearly impervious to hard impacts. If you're really abusive to gear, look for bezels made of Lexan or Pyrex.
Another option with both flashlights and headlamps is color filtration. When you are working in the dark and want to preserve your night vision, having the ability to filter the color of light you are using will help you avoid that lag time between viewing something with a light, then trying to see without it. In addition to green, you will find blue, red and infrared filters that greatly reduce the problem of working in the dark. Also, keep in mind that color filters are very useful for finding a deer stand or moving in to set up for any game before dawn, since four-legged animals are basically color blind and unable to see your light.
The main advantage of a headlamp is the convenience of hands-free operation. A headlamp is usually worn on the forehead, but some models offer side mounted lights. Regardless of the position on the head, with a headlamp, everywhere you look is illuminated. The only disadvantage is to others you may be hunting, camping or working with. When you talk to someone, and look directly at them at the same time, your headlamp will shine into their eyes. It takes a little getting used to, but I haven't found this to be a big problem when compared to the advantage of having both hands free and lots of directed light.
The same issues affecting brightness and hours of operation for flashlights are relevant to headlamps as well. One factor that is more pertinent to this type of device is weight. When selecting a headlamp, give serious consideration to weight as well as brightness and battery life. The amount of weight you are willing and able to tolerate on your head is a personal decision, most often affected by physical stature. Keep in mind that the weight of a headlamp will be cumulative over the period of time you intend on using it. While it may not be a significant factor if you're using one to set up camp or gather firewood at night, if you're hiking, fishing, field dressing a deer or frog gigging for hours on end weight can be an issue.
Without an electric source a flashlight or headlamp is only ballast in a backpack or pants pocket. To make sure you have light when you need it, consider the battery options available today before you make a purchase. The cheapest cost of battery power per kilowatt-hour is the traditional lead-acid battery, but who would want to lug a car battery to power a flashlight? The advantage of lightweight batteries must be compared to cost per kilowatt-hour of use and justified by convenience and frequency of use.
Primary (non-rechargeable) batteries are the standard AAA, AA, C, D and 9-volt alkaline units everyone is familiar with. Larger cell batteries provide a lower cost per kilowatt-hour than small cells, but their added size and weight is a disadvantage. The advantages of primary batteries are high energy density, long storage life and immediate operational readiness. No charging or priming time is required before use. Although secondary (rechargeable) batteries have improved, a regular household alkaline battery provides 50% more power than lithium-ion, one of the highest energy-dense secondary batteries.
Lithium Lithium batteries lead the world in reliability and safety, providing long-term storage life (up to 10 years) at room temperature and long operational life over a wide range of operating temperatures. The superior chemical and design characteristics of these batteries are well recognized for both performance and power value.
The primary lithium battery used in cameras holds more than three times the energy of a alkaline battery of equal size. The down side to primary batteries is they don't perform well when used at a high rate of consumption, and that's when secondary batteries perform better. The most distinctive limitation of the primary battery is its one-time use, which makes is about 30 times more expensive than rechargeable batteries.
Secondary batteries provide a far more economical source of energy than primary batteries, based on the initial purchase price and maximizing the number of discharge-charge cycles possible before replacement. Without proper and regular maintenance, the costs are significantly higher due to a shortened lifecycle.
In terms of life cycling, the most enduring power cell is the standard nickel cadmium battery. In terms of stable capacity, internal resistance and self-discharge over many cycles, the NiCad battery deserves an "A" for almost perfect performance. The down side, is that Nickel-cadmium batteries have a moderate energy density, require periodic full discharges and contain toxic metals. NiCad batteries are more prone to memory problems. Memory shortens battery life in everyday use if not properly maintained. Applying a full discharge/charge cycle once a month solves this problem. If NiCad batteries are used on a daily basis, the full discharge/charge cycle should be performed every 30-charge cycles.
These batteries perform well in their early stages, but past 300-cycles, they start to deteriorate rapidly. Nickel-metal-hydride (NIMH) batteries have a higher energy density than nickel-cadmium and do not contain toxic metals. Some experts maintain that Nickel-metal-hydride batteries are an interim step to lithium-ion. One advantage to NIMH technology is the lack of memory problems associated with NiCad batteries.
In laboratory tests, the lithium-ion battery gets high marks because they offer the highest energy density and contain no toxic metals. The Lithium-ion batteries strong suit is that it maintains an almost constant capacity throughout the discharge cycle. With lithium-ion batteries you should avoid frequent full discharges because this puts additional strain on the battery. Partial discharges with frequent recharges are far better than one deep charge with the lithium-ion battery. Keep lithium-ion batteries cool, and avoid leaving them in hot places like a vehicle in the summer. Store at a 40% charge level.
Lithium-ion batteries have a lifetime of two to three years and the clock starts ticking as soon as the battery comes off the assembly line. For this reason, do not purchase extra lithium-ion batteries for future use, and always pay attention to the manufacture date.
After consuming this wealth of data you should be ready to select a flashlight or headlamp that is totally in tune with your personal needs for illumination. Make your selection and let there be light!
March 25th, 2007 06:59 PM
March 25th, 2007 07:40 PM
Interesting and informative read - thx QK.
Chris - P95
NRA Certified Instructor & NRA Life Member.
"To own a gun and assume that you are armed
is like owning a piano and assuming that you are a musician!."
- a portal for 2A links, articles and some videos.
March 27th, 2007 07:18 AM
A lot to digest QK. You forgot to mention that all one really has to do is PM clipse and ask "whaddya think of this light?" I believe he's got 90% of all the lights ever made.
March 27th, 2007 10:01 AM
Its out of date. The newer LEDs such as Cree and Seoul aren't meantioned but there are many new lights coming out with them. The double the efficiency of luxeon LEDs.
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