The flashlight you will need depends on the task at hand. Below is information on bulbs, light measurement, battery choices, battery chargers, and a glossary of terms to assist you in choosing the light that's best for your specific needs.
BULBS
Flashlights can have several different kinds of bulbs. The biggest differences are the cost, runtimes, longevity and brightness.Incandescent Bulbs:
- Halogen Bulb - incandescent gas-filled bulb that blackens less when it ages than other types of bulbs. Halogens may have a longer life than a Xenon bulb of equivalent performance.
- Krypton Bulb - incandescent bulb filled with Krypton gas. Usually not as bright or long-lived as a Xenon or Halogen, but very economical.
- Xenon Bulb - incandescent bulb filled with Xenon gas. Xenon bulbs are an excellent choice for long distance performance because they provide an extremely bright, white light.
LEDs (Light Emitting Diodes):
- LEDs - very durable and long-lived, up to 100,000 hours of life and do not require periodic replacement like incandescent bulbs. LEDs are good for close work because of their wide dispersion and soft focus. Their solid-state construction makes LEDs safer than incandescents in hazardous environments provided the flashlight has a hazardous location rating. LEDs are available in various colors for different applications:
- White - allows you to see "True Color" because it is very close to natural light. The most popular for general use.
- Blue - an extremely bright light that is commonly used in forensics while also ideal for various automotive and industrial applications. The blue LED has similar characteristics of a black light.
- Green - also an extremely bright light that is great for Hunters because it does not spook game and preserves night vision. The International Hunter Education Association (IHEA) teaches students to associate a green light in the woods as another Hunter.
- Red - the red LED is best at preserving night vision, but does not provide as much usable light as the green LED. Ideal for signaling and aviation applications. Also, insects cannot detect red light so it is ideal for pest control personnel.
- Luxeon LEDs - provide the reliability of an LED with the performance of an incandescent bulb. Luxeon LEDs provide a much greater light output than standard LEDs (10x's brighter) and can be focused with a reflector. Like standard LEDs, Luxeon's are durable and do not require periodic replacement like incandescent bulbs. The expected lifetime of a Luxeon LED can be from 10,000 to 50,000 hours. Luxeon's are the latest in high power LED technology on the market today.
- Combination LED/Incandescent - LED/Xenon lights combine the long runtimes and durability of LEDs with the brightness of an incandescent. Considered the best of both worlds.
LIGHT MEASURMENT- All light measurements can be traced back to the Candela, which is the unit of luminous intensity. Most flashlight manufacturers use two basic methods to rate the light output of their products. Each is described below.
- Candlepower (Peak Beam Candlepower) - this is the measurement of the brightest spot in the focused beam. Candlepower is a function of the output of the lamp and the efficiency of the reflector.
- Lumens (Total Luminous Output) - a measurement of the total light output of the bulb. It is almost entirely a function of the bulb or LED. Focus is not considered.
BATTERY TYPES - there are two battery types: Disposable and Rechargeable. Disposable batteries generally offer longer runtimes for a given bulb power than rechargeables and are typically lower in initial purchase price. Long term operation costs are considerably higher with disposables than with rechargeables and are seldom as bright.Disposables:
- Alkaline - Alkaline batteries are readily available so its easy to keep spares on hand. They generally have a 7 year shelf life and are fairly cost effective. However, their performance is affected by, and drops off very quickly in cold weather. Also, they are at their brightest when first used and decline thereafter.
- Lithium - Lithium batteries are more cost effective than Alkalines and have a good low temperature tolerance. They maintain a high light output that's longer than Alkalines for equal power levels. Lithiums also have a longer shelf life; 10 years, versus a 7 year shelf life for Alkalines.
Rechargeables:
- Nickel Cadmium (NiCd) - the Nickel Cadmium rechargeable technology provides the highest performance/cost ratio. They can be recharged overnight with low cost economical chargers or fast charged with more expensive chargers. NiCd's are rechargeable up to 1000 times but they self-discharge in storage so they mush be periodically recharged or stored in their charger. NiCd's mush be disposed of properly or recycled.
- Lithium Ion - the Lithium Ion performs like the Nickel Cadmium but with about half the size and weight. Lithium Ions have a low self-discharge rate and good low temperature performance. They are recyclable up to 300 times and have no recycling requirements.
CHARGERS - There are typically two kinds of chargers available for rechargeable batteries. The Standard Charger recharges batteries in about 10 hours. The Fast Charger recharges your batteries in approximately 2.5 hours. To be sure your flashlight is ready to go, it's a good idea to have a set of fully charged batteries in your flashlight and a set of batteries in your charger.
GLOSSARY OF TERMS:AMP - abbreviation for ampere and amperage. Unit used to measure electric current
- Ampere-hour - one ampere of current flowing for one hour
- Anodizing - an electro-chemical coating for aluminum. Hard, durable and highly corrosion resistant
- Bezel - front part of the light that includes the lens, reflector, and/or bulb
- Bi-Pin Bulb - a bulb with two contact pins that plug into a socket allowing easy replacement
- Candlepower - the measurement of the brightest spot in a focused beam. Also known as Peak Beam Candlepower
- Dual Filament - a dual filament bulb contains two filaments, which enables users to instantly switch to the second filament when back-up lighting is needed
- Fast Charger - a transformer used for quick charging of lights and may also have capabilities of being used with different overseas currents
- Halogen Bulb - a clean burning bright bulb that maximizes light output with halogen gas that helps keep the interior of the bulb clean
- High Temperature Lens - typically made of borosiclicate glass, which has low thermal expansion characteristics. Easy to clean, resists scratching, and has good shock resistance when properly mounted
- Incandescent - a bulb which uses a thin filament with electrical current passing through it
- Intrinsically Safe - not capable of igniting a flammable atmosphere under both normal and "fault" conditions
- LED - Light Emitting Diodes. Durable and long-lived. Up to 100,000 hours of run time. Do not require periodic replacement. Soft focus, short range. Good for close work. Less power than incandescent but can give 100's of hours of run time at low illumination levels
- Lumen - a measurement of the entire output of the bulb. Focus is not considered
- Machined Aluminum - flashlight components made from this material are lightweight, durable and can be held to tight manufacturing tolerances for superior performance in precision assemblies
- NiCd - Nickel-Cadmium rechargeable battery
- NIMH - Nickel-metal hydride rechargeable battery
- Non-Incendive - not capable of igniting a flammable atmosphere under normal operating conditions
- Non-Conductive - will not conduct electricity. Flashlights made with non-conductive case materials protect against electric shock should the flashlight touch an electrical source
- O-Ring - used as a gasket to seal the flashlight case against dust and moisture
- Peak Beam Candlepower - the measurement of the brightest spot in a focused beam. Also known as Candlepower
- Polycarbonate - clear, tough, shatterproof, virtually unbreakable polymer used to make the lens in flashlights. Often hard coated for abrasion resistance
- Pre-Focused Lamp Module - lamp and reflector furnished and replaced as a unit. Permanently adjusted for optimum focus
- Reflector - surrounds the lamp and directs and focuses the light rays in one direction
- Run-Time - how long batteries will last
- UL - Underwriters Laboratories, Inc. A third party testing organization that approves products for compliance to electrical specifications and for use in specified hazardous locations
- Volt - unit of electrical potential. The potential difference between tow points in an electrical system is called the voltage between those points
- Watt - unit of power. Electrical power can be calculated by multiplying voltage times amperage
- Xenon Bulb - a clean burning bright bulb that maximizes light output with Xenon gas that helps keep the interior of the bulb clean