Lux changes depending on how far this surface is from the light source. Lux (lx) is used to measure light on a particular surface. Long distance flashlights with a concentrated beam spot have higher candela than floodlights which spread the beam. This means that if you shine a flashlight on an object 20 meters away and then shine it on an object 10 meters away (half the distance), the nearer object will be 2^2 (2 squared) times brighter i.e. The intensity of light reduces according to the 'inverse square' law. In simple terms, more intense light (higher candela) will travel further than weaker intensity light (lower candela). Lumens and candela get confused like 'voltage' does with 'current'. It is a measure of intensity, rather than brightness. The term candela is derived from abbreviating the phrase 'candle power'. But if the light emitted from this apparatus is narrowed and made to shine within a 20-degree beam, then its candela value will increase to 18,000. For example, a standard fluorescent lighting device that emits a wide-spread beam can have a rating of 1,700 lumens and 135 candelas. Lumen ratings do not consider the spread of the light being emitted in degrees, whereas candela ratings do. If you want an evenly illuminated area, with a less bright spot and do close up work, like reading a map, a flashlight with a lower candela rating is for you! High candela rated torches are good for visibility in smoke and fog and if you want a concentrated beam. Candelas measure light intensity in only 1 direction.Ī higher candela rating indicates a longer beam distance because more intense light travels further. 36,200 trillion-trillion lumens! That's why you can't directly look at it!Ĭandelas (cd) help with understanding how focussed and intense the light source is. On a bright day, in a hot country, each square metre outdoors has approximately 133,200 lumens.
(This means that the Wuben A9 is 4 times brighter than a HID car headlamp!)
Approximate examples: birthday candle-1 lumen, phone flashlight-80 lumens, 40 watt incandescent (filament) bulb-460 lumens, 60 watt incandescent bulb- 800 lumens, 4 foot 32 watt T8 tube light-2500 lumens, HID car headlight-3000 lumens. Lumens (lm) is a measurement of how much light is emitted in all directions. So let's look at some important torch related definitions: What is a Lumen? Using a 5 lumens keychain torch for search and rescue probably won't help much and using a 12000 lumens flood torch (such as the Wuben A9) is going to be more than what you need for when locking a gate at night. Having the correct flashlight for the correct job is important. What's the difference between 'lumens', 'candela', 'lux' and 'throw'?
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