Flashlight, is a hand-held electronic lighting tools. A typical flashlight has a battery-powered bulb and focusing mirrors, and a hand-held housing for hand-held use. Although rather simple in design, it was not invented as late as the end of the nineteenth century, because it had to combine the invention of batteries with light bulbs. In the early days because of the lack of battery power, so in English it is called "Flashlight", which means a short light.
CREE LED also has a lot of series and models, here simply discuss about several commonly used types . (As MCE, P7, SST50 are the old products, low efficiency will not be mentioned)
XRE Q5-WC, XPG R5-1A, XML T6-1B
Above is several CREE common LED.
Q5, R5, T6 refers to the LED level.
The level of XRE is P3 P4 Q2 Q3 Q4 Q5 R2
The XPG rating is R3 R4 R5 S2 S3
The level of XML is T4 T5 T6 U2 U3
The higher the level, the higher the luminous efficiency. Brightness difference between every two levels of about 7%, the naked eye can not be accurately distinguished. XRE, XPG, XML refers to the LED series.
In addition to these types, there have been flashlight XRC, XPE, XPC, MCE and so on. Series means the appearance is the same. XRE luminous angle is the smallest, suitable for long-range flashlight. XPG luminous core area and angle is larger than XRE , XML light-emitting core and angle is the largest. These two kinds need a higher requirement on the light cup size for made of concentrating type flashlight, but is better on floodlight . The actual use of flashlight is mainly on flood lighting.
Generally if not a senior flashlight enthusiasts, to judge the brightness of the flashlight, only need to observe the center of the brightness of the spot. In fact, the brightness of the center spot can only reflect the flashlight intensity, but can not explain the overall luminous flux of flashlight. higher light intensity doesn't mean higher lumens! Only the smaller angle of LED light, greater light cup size to ensure the better condenser, light intensity is certainly high. So it's possible that a large caliber light cup XRE Q5 flashlight is brighter in central spot than the small caliber light cup of XML T6 flashlight. But if you use both in the night, you will find XML flashlight cover area and brightness are a lot better!