How to Choose a Torch Flashlight

by Xue Li Gadgetsdealer

Key factors when selecting a torch flashlight include:Size and weight,How intense (or bright) is its light source?What kind of battery life can it provide?Size and weight are fairly easy to evaluate. Gauging the other factors involves a little comparative research.

Types of Torch Flashlight

Common light sources for torch flashlight include:

LEDs: Short for light-emitting diodes, a simple type of semiconductor. They excel in energy efficiency while offering good, all-purpose proximity lighting for camp chores, map-reading and close-up work.
High-output LEDs: 3-watt LEDs rival the brightness of pressurized-gas bulbs; 1-watt LEDs produce a light intensity that matches up well with standard incandescents--only they use much less battery power.
Xenon, halogen or krypton bulbs: Incandescent bulbs that contain a pressurized gas such as xenon. When introduced into a bulb's glass casing, these gases prevent oxidation of the filament, controlling soot buildup that tends to darken traditional bulbs. As a result, these bulbs burn with high intensity.
Incandescent bulbs: Traditional bulbs filled with an inert gas, such as argon; they usually cast farther-reaching beam and produce higher lux numbers than standard LEDs.

LEDs are growing more prevalent in flashlights. They already are the dominant lamp type used in headlamps.

Key benefits of LEDs:

They drain batteries 3 to 5 times slower than traditional incandescent bulbs.
LEDs can have a life span of up to 100,000 hours; an incandescent bulb may burn out in less than 40 hours.
With no glass or filament to break, LEDs are very tough and ideal for rugged use.

Pressurized-gas bulbs still lead the pack in terms of highest lux numbers, but high-output LEDs continue to evolve and narrow that gap. It is widely expected that future generations of LEDs will outperform all incandescents.

Flashlight Performance

New methods for testing flashlight performance are in development even as this article is being written (in late 2007). New criteria for determining light output and beam strength (involving lux, lumens and other measurements) are expected to bring flashlight specifications (specs) into greater conformity with a recently accepted testing protocol for headlamps.

For now, REI's Quality Assurance Lab independently tests flashlights and provides the following two specs for each model:

Half-life brightness: This is a measure of how intensely a flashlight's light source can project a beam when its batteries are 50 percent drained of their energy reserves. The number shown in our spec charts is foot candles, measured by a light meter. In simple terms, the higher the number, the greater the light intensity (or brightness) a flashlight delivers midway through the life cycle of a set of batteries.

Battery life: We test in an area where a constant temperature of 70®F is maintained. We insert fresh batteries, switch the flashlight on and monitor its run time until it goes dark. That length of time is recorded under "battery life @ 70®F." If a flashlight offers more than one mode (and high and low mode, for example), we usually include the run times for both modes.If read more just go ahappydeal.

Key Flashlight Features

Beam Pattern

The parabolic reflectors that surround lamps influence how effectively a flashlight channels (or spreads) light. You can choose from three general pattern options:

Flood (or fixed; wide): A single beam width; no adjustability. Good for slower-paced general tasks in camp or while walking.
Spot (or focused): LED models with specialized lenses that condense the beam into a spotlight, throwing a narrow beam a long distance. This is often preferred during route-finding or other fast-paced activity.
Adjustable: Beam width can range from wide to narrowly focused or in-between. It's a nice feature. A climber looking for the next pitch would use a spot beam; to study a map, a flood beam.

Regulated Output

Some lights include a regulated power supply, and it can be a desirable feature.

Unregulated lights start bright then progressively grow dimmer as they draw power from a set of batteries. Batteries tend to last longer when used in unregulated lights.

With a regulated power supply, lights maintain a steady, near-peak brightness level throughout most of the batteries' life cycle. Near the end, though, light output will drop off abruptly and significantly. In some cases, the light will simply go dark. Thus you may be forced to change batteries in the dark.

Other Considerations

Modes: Simple lights provide a single setting--quite sufficient for general-purpose use. Other models offer two or more modes--low, medium, high and potentially more). You may rarely use more than one mode, but having the option to throw an extra-strong beam on demand can be a reassuring luxury.From the china shop online you can find the cheap flashlight.

Weight: Typically, size and battery capacity directly relate to the strength of the beam a flashlight can project. Naturally, flashlights that require multiple D cell batteries will be heavier, more powerful units.

Batteries: Some flashlights come packaged with batteries included. A few flashlights are designed to work with rechargeable batteries that are activated by winding or shaking--excellent for emergency kits. A few lights work with lithium or lithium-ion batteries.

IMPORTANT: Do not attempt to use lithium or lithium-ion batteries with any light unless manufacturer instructions state that the specific light is designed to operate with lithium batteries. If not, you run the risk of damaging, even ruining, a light by mismatching it with lithium batteries.