Light bulb buying guide 3

What other factors will I want to consider?

So far, we've covered the light bulb basics (and then some), but if you really want to get picky about your home lighting, or if you just want to delve a little deeper into the subject, there's a lot more to take into consideration.

Bulb shape

As you're probably aware, light bulbs come in a fairly wide variety of shapes. Sure, it's easy enough to tell a hardware store clerk that you want "one of those flamey-looking lights," or "just a normal ol' bulby light bulb," but knowing the actual nomenclature might save you some time.

Let's start with the base of the bulb, the part that screws in. In the US, the most common shape by far is E26, with the "E" standing for Edison and the "26" referring to the diameter of the base in millimeters. You might also see E27 bulbs from time to time, which is the European standard. Those should still fit into common American fixtures, but keep in mind that voltage ratings are different in the two regions, with American bulbs rated for 120 volts compared to 220-240 volts in Europe. For smaller sockets, like you might find with a candelabra, you'll want to look for an E12 base.

As for the bulb itself, the typical shape that you're probably used to is an A19 bulb. Increase that number to A21 or A23, and you've got the same shape, but bigger. Bulbs made to resemble flames are F-shaped, which is easy enough to remember, as are globes, which go by the letter G. If it's a floodlight you want, you'll want to look for "BR" (bulging reflector) or "PAR" (parabolic aluminized reflector). Those bulbs are designed to throw all their light in one direction only, which makes them useful for spot lighting, overhead lighting, and the headlights in your car.

Directionality

Some lights have hardware built into the bulb itself that can block the downward projection of light (BR and PAR bulbs do it intentionally, reflecting that light back upward). These bulbs are fine for something like a recessed light fixture, where they can hang upside down and shine straight out, but if you're buying one for a bedside reading lamp, where downward light is key, it might be disappointingly dim. If you aren't sure exactly what you'll need from your bulb in terms of light direction, the safe bet might be to go with a bulb that shines in all directions. The term that you'll want to look for is "omnidirectional."

In addition, some nonomnidirectional lights will offer you an idea of just how close to omnidirectional they actually are. 360 degrees of light output is the obvious ideal, but a bulb that offered 330 degrees would probably be close enough.

Dimmability

A majority of modern lighting options now include compatibility with in-wall dimmer switches, and that's a good thing for anyone who likes the light down low. If this sounds like you, then you'll want to double check that your bulb's packaging says the word "dimmable" before you make a purchase.

That said, some bulbs will dim down better than others -- and your mileage may vary depending on what switch you're using too. Most basic switches dim the light by flashing the power on and off faster than the eye can detect. In many cases, this can cause electromagnetic interference in the bulbs, which can lead to flickering light or a faint buzz from within the bulb.

What about smart lighting?

It's out there, and it's more affordable than you might think. Whether you want an elaborate network of fully automated lights, or just a simple bulb that you can program over your phone via Bluetooth, you'll find a growing number of options available from a variety of different sources.

Automated lighting

It used to be that if you wanted your lights to turn on and off automatically, then you had to rely on a cheap wall socket timer, the kind you might use to control a Christmas tree. With a modest boom in smart lighting currently under way, it's easier than ever to dive into the sort of advanced automation controls that can make any home feel modern and futuristic. With the right devices, you'll be able to control your lights in all sorts of creative ways, and make your life a little bit easier in the process.

For lighting control as part of a larger home automation system, one that's capable of tethering the status of your lights to things like motion detectors, smart locks, or presence sensors, you could turn to a system like Insteon's. The company's starter kits aren't quite as flashy as some of the other new automation options we're seeing, but it'll work well if you're looking to automate your lights. You could even upgrade your system with a few of Insteon's fully automatable LED Bulbs, while you're at it. We've also seen interesting, LED-friendly systems from startups like SmartThings , so you'll definitely want to do a little research and shop around before committing to anything too elaborate.

Keep in mind, though, that many of these bulbs will need to draw a tiny bit of power while they're powered off in order to remember your automation settings, and this means that they'll be slightly less energy-efficient than normal bulbs. For green-minded consumers, this kind of bulb might not seem smart at all.

Even if a color-coordinated level of smart functionality makes your eyes roll, it still illuminates one last important thing about buying lights: you should look for the lighting setup that you'll enjoy the most, because you'll be using it more often than any other appliance in your home. Even if smart lights aren't for you, there's no reason not to be smart about your lighting choices. Know your options, shop intelligently, and you'll love your lights for years to come.

Light bulb buying guide 2

Incandescents

Average cost: $1 to $10
Average wattage: 40W to 150W
Average life expectancy: 1,000 hours

When I tell you to picture a light bulb, chances are good that you're envisioning an incandescent. This is the classic bulb of Thomas Edison: a tungsten filament trapped within a glass enclosure. Electricity heats the filament to a point where it glows, and voila, you have light.

Aren't incandescents banned?

As a matter of fact, they aren't. EISA doesn't actually ban anything, at least not directly. What EISA doesdo is raise efficiency standards -- specifically, the minimum acceptable ratio of lumens (light) per watt (electricity). Incandescents aren't banned; they simply have to become more efficient. Also, keep in mind that appliance lights and other specialty classes of incandescents are exempt from the new standards, so they aren't going anywhere.

It's true that traditional incandescents unable to keep up with the times will be phased out. However, the door is still wide open for non-traditional incandescents to take their place, and we're already seeing some manufacturers rise to the challenge, with high-efficiency incandescent bulbs that manage to meet the new standards. Key among these high-efficiency bulbs is yet another lighting option you'll want to consider.

Halogens

Average cost: $2 to $15
Average wattage: 29W to 72W
Average life expectancy: 1,000 hours

Halogens are just incandescent bulbs with a bit of halogen gas trapped inside with the filament. This gas helps "recycle" the burned-up tungsten gas back onto the filament, making for a slightly more efficient light. Unlike the mercury in CFLs, this gas isn't anything that could be classified as hazardous waste.

Due to their relative similarity to classic incandescents -- both in light quality and in cost -- halogens can work as a good compromise bulb for consumers who need to replace their incandescents, but who also aren't ready to commit to CFLs or LEDs quite yet.

What information should I be looking for?

You want to be sure that you'll enjoy living with whatever light bulb you purchase, especially if you're choosing a long-lasting bulb that you'll live with for years. Fortunately, the Federal Trade Commission now requires light bulb manufacturers to put a "Lighting Facts" label onto their products' packaging, not unlike the Nutrition Facts label that you'll find on packaged food.

These Lighting Facts include everything from the estimated yearly cost of using the bulb to more obscure figures, like lumens and color temperature. If you want to shop smart, it will help to understand as much of that terminology as you can.

Lumens

If you're buying a bulb these days, you'll be left in the dark if you don't know what a lumen is. The actual definition gets a bit complicated, involving things like steradians and candela, but don't worry, because all that you really need to know is that lumens are units of brightness. The more lumens a bulb boasts, the brighter it will be. So, how does this information help you?

Let me give you an example. If you look at CFL or LED bulbs, you'll see that most all of them are marketed as "replacements" for incandescent bulbs of specific wattages. You'll probably see the word "equivalent" used, too, as in "60-watt equivalent." This can be frustratingly misleading, with "equivalent" often meaning something closer to "equivalent...ish."

Relying on these wattage equivalencies can lead you to buy a bulb that ends up being far too dim or too bright for your needs, and this is where understanding lumens really comes in handy. With lumens listed on each and every bulb, you'll always have a concrete comparison of how bright any two bulbs actually are. The bigger the number, the brighter the bulb -- easy enough, right?

How many lumens do I need?

Over the last century, we've been trained to think about light purely in terms of wattages, so it isn't surprising that most people really have no idea of how many lumens they actually need in a bulb. Until you form an idea of how bright is bright enough for your tastes, stick with these figures:

Replacing a 40W bulb: look for at least 450 lumens
Replacing a 60W bulb: look for at least 800 lumens
Replacing a 75W bulb: look for at least 1,100 lumens
Replacing a 100W bulb: look for at least 1,600 lumens

Color temperature

After lumens, the next concept you'll want to be sure to understand is color temperature. Measured on the Kelvin scale, color temperature isn't really a measure of heat. Instead, it's a measure of the color that a light source produces, ranging from yellow on the low end of the scale to bluish on the high end, with whitish light in the middle. An easy way to keep track of color temperature is to think of a flame: it starts out yellow and orange, but when it gets really hot, it turns blue.

Generally speaking, incandescents sit at the bottom of the scale with their yellow light, while CFLs and LEDs have long been thought to tend toward the high, bluish end of the spectrum. This has been a steady complaint about new lighting alternatives, as many people prefer the warm, familiar, low color temperature of incandescents. Manufacturers are listening, though, and in this case they heard consumers loud and clear, with more and more low-color-temperature CFL and LED options hitting the shelves. Don't believe me? Take a look at those two paper lamps in the picture above, because they'reboth CFL bulbs -- from the same manufacturer, no less.

These days, bulb shoppers will find so many color temperature options that some lighting companies have cleverly begun color-coding their packaging: blue for high-color-temperature bulbs, yellow for low-color-temperature ones, and white for bulbs that fall in between. With so many choices available, the notion that the phase-out of incandescents is taking warm, cozy lighting with it is a complete myth at this point.

Color rendering index

Unless you live in a disco, you probably want the colors in your home to look somewhat traditional. This is where the color rendering index, or CRI, comes in. The CRI is a score from 1 to 100 that rates a bulb's ability to accurately illuminate colors. You can think of the CRI as a light bulb's GPA for colors, as it actually averages multiple scores for multiple shades. Manufacturers aren't required to list the bulb's CRI number on the packaging, but many of them choose to do so anyway, so you'll want to know what it means.

In general, anything over 80 is probably decent enough for your home, but we're starting to see CRI scores creeping up into the nineties on some very affordable bulbs. If accurate color rendering is important to you, hold out for lights like these. And if you're buying bulbs on the high (blue) or low (yellow) end of the spectrum, take any and all CRI claims with a grain of salt.

How do I tell if a light bulb is efficient?

In simple terms, a light bulb is just a device that converts electricity into light. The more light you get per watt of electricity, the more efficient the light. With incandescent bulbs, efficiency is easy to understand because a specific wattage of electricity will always heat a tungsten filament to a specific temperature, which in turn will yield a specific level of light. This means that, generally speaking, one incandescent will be more or less as efficient (or by today's standards, inefficient) as another.

With LEDs and CFLs, the bulbs still convert electricity into light, but the methodology is totally different. Light output isn't fixed to the temperature of a filament, which means there's more wiggle room for differences in efficiency. Simply put, unlike incandescents, LED and CFL bulbs are decidedly notcreated equal.

This is another place where understanding lumens comes in handy. A 10W LED can easily outshine a 12W competitor if it converts watts into lumens more efficiently. All the wattage tells you is how much power the bulb uses. The lumens tell you how much light the bulb puts out. The ratio between the two tells you how efficient the bulb is. The more lumens you're getting per watt, the better the bulb is at converting electricity into light.

Light bulb buying guide1

With strict new standards, the landscape of lighting is rapidly changing. Here's everything you'll need to know to keep up.

When Congress passed the Energy Independence and Security Act of 2007 (EISA), the incandescent bulb's days officially became numbered. The law mandated strict new energy standards for lighting designed to kick-start a new era of greener, longer-lasting, more cost-efficient light bulbs -- and this meant kicking outdated, inefficient bulbs to the curb.

The rising standards have already rendered 100W and 75W incandescents obsolete, and on January 1, 2014, their 60W and 40W cousins met the same fate. Congressional budget waffling seemed to put the new standards on hold, but it was largely too late -- the industry had already moved on, and wasn't interested in reversing course.

Like it or not, the arrival of this new era means that replacing your lights will never be quite the same. With all of the new options out there (not to mention the disappearance of some important old ones), finding the perfect bulb can seem pretty daunting. New lights that promise to last 20 years and save you hundreds of dollars might sound good in theory, but how do you know which one is the right one for you? How do you know the bulb you're buying is going to be bright enough? And what if you're just not ready to say goodbye to your incandescents?

Well, fear not, because we've got you covered with a handy guide that's chock-full of all the information you'll need to make sure that your next light bulb is the right bulb.

What kinds of bulbs are available?

We've all gotten to know incandescents quite well over the past 135 years or so, but times are changing. These days, you've got some new lighting categories to familiarize yourself with, and doing so is the first, most obvious step toward buying the right bulb.

LEDs

Average cost: $5 to $25
Average wattage: 4W to 22W
Average life expectancy: 20,000 hours

Light-emitting diodes, or LEDs, are the new rock stars of the bulb world. When an LED is switched on, electrons and electron holes come together (don't worry, I'm not completely sure I fully understand what a " hole" is in this context, either). The result of this process is a release of energy in the form of photons, or light.

A typical LED uses a fraction of the wattage required to power a bright incandescent bulb, and this makes LEDs dramatically more cost-effective over the long run. A 12W LED that puts out 800 lumens of light (lumens are units of brightness for a light source -- more on that in just a bit) will add about a buck and a half per year to your power bill if used for 3 hours a day at an energy rate of 11 cents per kilowatt hour (kWh). Under those same parameters, a 60W incandescent bulb that puts out 880 lumens will cost about $7.50 per year. Multiply that by the total number of bulbs in your home, and you're potentially looking at some pretty significant long-term savings.

LEDs are also rated to last for tens of thousands of hours, which can translate to decades of use. Compare that with the year or so you typically get out of an incandescent, and you can begin to see why so many people find these bulbs appealing. At a price of about $15, that 12W LED would pay for itself in 2.5 years, then keep on saving you money for years to come.

This Insteon LED promises to last for a whopping 52,000 hours.

Decades? Really?

Yes, really -- at least, according to Energy Star and the Illuminating Engineering Society (IES), the independent organization that created the testing procedures manufacturers use to rate LED lights. Most LED bulbs have only been commercially available for a few years now, not nearly long enough to see direct proof of their longevity claims. Fortunately, there's enough transparency with LED testing that we're able to dig a little deeper into what these claims are actually saying.

First, it's important to understand that LED lights don't "burn out," the way that incandescents do. Instead, they undergo "lumen depreciation," gradually growing dimmer and dimmer over time. The test that the IES uses to determine a bulb's longevity is known as the LM80, and it calculates how long it will take for an LED to fade noticeably. Engineers run the bulb for nine months in order to get an accurate read of the light's rate of decay, and using those figures, they can calculate the point at which the light will have faded to 70 percent of its original brightness. This point, known as "L70," is the current standard in LED longevity. If an LED says it'll last 25,000 hours, it's really saying that it will take the bulb 25,000 hours to fade down to 70 percent brightness.

This isn't to say that LEDs don't fail. They definitely do. As with any device relying on tiny, delicate electrical components, things can go wrong. Fortunately, more and more LED bulbs come with multiyear warranties for cases of mechanical failure. Some manufacturers, like GE and Cree, offer bulbs with 10-year warranties, none of which cost more than $20. Consumers with a healthy dose of skepticism regarding LED longevity claims should look for bulbs like these, by manufacturers willing to put their money where their mouth is.

CFLs like this one are great energy-savers.

CFLs

Average cost: $2 to $20
Average wattage: 9W to 52W
Average life expectancy: 10,000 hours

Before LEDs exploded into the lighting scene, compact fluorescent lights (CFLs to you and me) were seen by many as the heir apparent to incandescent lighting. Despite the fact that CFLs use between one-fifth and one-third the energy of incandescents, and typically save one to five times their purchase price over the course of their lifetime, many people weren't thrilled at the idea of switching over. Some find the whitish light output of CFL bulbs less aesthetically pleasing than the warm, yellow tone of most incandescents. Others are quick to point out that CFL bulbs that regularly get powered on and off for short periods of time tend to see a significant decrease in life expectancy. There's also the common complaint that most CFLs aren't dimmable, and that they often take a second or 2 after being switched on to fully light up.

The good news here is that CFL technology has improved a lot since EISA was signed into law in 2007. Today, you'll find a greater variety of color options, including bulbs rated at the low, yellow end of the Kelvin scale, and you'll have an easier time finding dimmable CFLs, too. There are even "instant-on" CFL bulbs designed to eliminate that annoying delay between flipping the switch and seeing the light.

The bad news is that in spite of these improvements, CFLs remain somewhat flawed. They're still prone to decreased life expectancy when you use them in short increments, so ideally you'll want to save them for lighting that you're going to keep on for longer periods of time. Additionally, most CFLs aren't intended for outdoor use, and some will fail to turn on in colder temperatures -- although you can find cold-cathode CFL bulbs rated for temperatures as low as -10 degrees Fahrenheit.

LED Lighting Efficiency Jumps Roughly 50% Since 2012

Well, looks like the 2007 law phasing out 100-year old incandescent light bulb technology in favor of newer light bulbs that waste less energy while providing more efficient lightingoptions is working.

Light-emitting diode (LED) light bulbs have improved their efficiency roughly 50% and expanded consumer options as federal regulations have tightened, according to a report from the U.S. Energy Information Administration (EIA).

At the same time, LED prices have continued dropping “dramatically” according to EIA, to the point where they make long-term economic sense for consumers even without government energy efficiency incentives.

Rising LED Efficiency, Falling LED Prices

Between 2012-2014 LED efficiency jumped from just over 60 lumens per watt to nearly 100 lumens per watt, and they may hit 150 lumens per watt by 2020. Compare LEDs to compact fluorescent lights (CFLs) with 55-70 lumens per watt, and traditional incandescent bulbs with 13-18 lumens per watt, and the LED advantage is bright as day.

LED manufacturers are not only increasing efficiency, they’re expanding options. EIA reports several manufacturers released Energy Star-qualified LED bulbs surpassing 100 lumens per watt in September 2014.

Consumer costs have been lowered even further through dozens of energy efficiency incentives. EIA estimates consumers received$400-470 million annually between 2011-2013 on efficient lighting through the Energy Star program, which maintains a list of available U.S. energy efficiency incentives online.

As a result of falling prices and favorable incentives, LEDs keep gaining market share. LED shipments skyrocketed from around 9 million light bulbs in 2011 to over 45 million bulbs in 2013. That’s good for around 2.3% of the general lighting market and combined with CFL shipments of 300 million annually since 2011, mean efficient lighting now makes up nearly a quarter of the U.S. lighting market.

Can LED Lighting Overcome The Color Rendering Index?

But even with all these cost and efficiency improvements, there’s still one aspect of lighting where LEDs don’t compete – the “warmth” of light given off by the bulb, as measured by thecolor rendering index (CRI).

Traditional incandescent bulbs have a CRI around 100, and while many LEDs have CRIs ranging from 20-30 (meaning a “cool” light), EIA notes several LED manufacturers have produced CRI values above 80. But again, technological advances are cutting that gap, as with Cree’s 2013 release of an LED with a CRI of 93. EIA also notes consumer studies reportlow correlation between consumer ranks and CRI values, meaning a low CRI doesn’t mean poor light quality.

And besides, with so many potential benefits to using LEDs combined with the positive low-cost and high-efficiency momentum, it’s going to take a lot more than just “cold” light to dim the outlook for efficient lighting.

November 5th, 2014 by Silvio Marcacci 

The City Of Sydney's LED Lights Saved $370,000 And Cut Power Usage By 34 Per Cent

LED lights are great. They’re more energy efficient than incandescents, they provide better quality light than sodium and tungsten lamps and they’re less prone to failure than fluorescents. (Although Hollywood movies will never look the same.) The City Of Sydney has installed over 4000 LED globes in city street lights so far, and the results speak for themselves.

Those 4100 LED lights installed since March of 2012 have lowered the city’s energy costs by more than a third; since public lighting itself accounts for more than a third of the entire energy bill that’s a pretty significant dollar saving. $370,000 has been saved thanks to the switch over to LED lights, which consume a fraction of the power of alternatives and have a much longer lifespan, massively reducing overheads for replacement globes and maintenance work.

LED lighting also appears brighter than existing tungsten or sodium lamp lighting because it produces light over a broader range of the colour spectrum, looking closer to daylight — which itself covers the entire colour spectrum and is the light that we’re most used to seeing. The lights have been installed all across the City’s residential and commercial areas including Newtown and the new developments at Zetland; on the back of the work the NSW government is encouraging other councils across the state to consider switching too.

The City of Sydney has 22,000 street lights across its local government area; while 13,500 are the responsibility of the City’s energy partner Ausgrid that leaves 8500 globes under the ownership of the City. A full 6500 are set to be swapped over to LED, and with 4100 complete nearly half are already there at this current milestone.

The City got a gong recently at the 2014 Institute Of Public Engineering Australasia awards, recognising its groundbreaking work in energy efficiency and greening — as well as the changes to street lights and the push for pan-city smart power usage, it has tried some pretty out-of-left-field ideas like installing lighter-coloured tarmac to reduce heat-soak and combat the effects of climate chan.

From CAMPBELL SIMPSON on the Science of GIZMODO.

YOU CAN FIND MORE PRODUCTS OF LED IN THE ONLINE SHOP http://www.ledgrossiste.fr .

Hong Kong International Lighting Fair

Hong Kong, Oct 27, 2014 - (ACN Newswire) - The 16th HKTDC Hong Kong International Lighting Fair (Autumn Edition) opened today at the Hong Kong Convention and Exhibition Centre (HKCEC). The fair, organised by the Hong Kong Trade Development Council (HKTDC), runs until 30 October.

Some 2,500 exhibitors from 37 countries and regions, including new participants from Lithuania, Mexico and Portugal, showcase the latest lighting products, technologies and smart lighting solutions.

To maximise business opportunities for exhibitors, the HKTDC has brought together 73 buying missions comprising nearly 5,900 buyers from 4,000 companies around the world for this event. These include a number of renowned distributors from emerging markets, such as Evrosvet and Light Time Group from Russia, Crompton Greaves Ltd and Future Retail Pvt Ltd from India, Adrilux Polska and IQ Led from Poland and Al Abdul Karim Holding Company from Saudi Arabia.

Star Performers

The fair features leading brands at the popular Hall of Aurora, which returns this year with over 490 worldwide brands, including CREE, MEGAMAN, Neo-Neon, Panasonic, Philips and Ford. Hall of Aurora provides an ideal venue for buyers to source high-quality products based on design, quality and performance.

Environment Spotlight

At the LED & Green Lighting zone, more than 850 exhibitors are displaying a variety of LED and environmentally-friendly indoor and outdoor lighting products for residential and commercial use, including such sectors as advertising, retail and architecture.

In The Zone

Other zones include Advertising Lighting featuring products such as display panels, light boxes and neon signs. The Smart Lighting & Solutions zone showcases lighting design services and software as well as management system and control panel solutions. There are also zones for Commercial Lighting, Household Lighting, Outdoor Lighting, Testing, Certification & Inspection, Trade Service & Publication and Lighting Accessories, Parts & Components. The Avenue of Inspiration spotlights young designers and startups with lighting design capabilities.

Small Orders, Big Prospects

In response to the growing demand of smaller and frequent orders, Small-Order Zone is back with 160 showcases on display, offering more than 1,600 products in minimum orders ranging from five to 1,000 pieces. The online Small-Order Zone has been transformed from an enquiry based to a transactional platform in April 2014, facilitating SMEs to expand their businesses riding on the global e-commerce trends.

Leading Lights

Experts in the lighting industry will share their knowledge and experience during a variety of seminars throughout the fair period. Topics to be covered include the prospects for the global lighting market, the latest industry standards and requirements for LED products, Hong Kong's accredited testing and certification services and development trends of mature and emerging markets. A seminar on "Lighting for a Connected World" will take a close look at the sensors and networks that are likely to shape future lighting trends.

How Much Do You Know about the “Three Mistakes” When Buying LED Lights

At present, LED illumination lamps and lanterns are more and more popular and pervasive with the explosive growth of LED industry output value. Moreover, people have fallen in love with spark LED lights and can’t leave them in daily life and work. 
However, because of poor LED technology standard, excess production capacity and cutthroat competition between enterprises, many of LED lighting products aren’t good in quality. Also, people know no much knowledge about LED lights when choosing them.

Keep it in mind with the advices of the following three mistakes:

Mistake One: Have excessive expectations to actual service life of LED lights
Generally, LED manufacturer anticipate LED service time up to 100,000 hours MTBF (Mean time between failures-standard that traditional lamps manufacturers use for measuring lifespans of light source). But the LED luminous flux lumens also decrease over time like more all of basic light source. Therefore MTBF isn’t the unique considering factor to confirm the service life of LED even through the time of LED lighting is very long. The attenuation of LED lumens is affected by some environmental conditions, such as temperature, humidity and ventilation, also including control, thermal management, current level and other electric design factors.
So with the light source, brightness of light has a gradually attenuation and dimming process and this process is called lumen decrease. 
When you buy LED lamps and lanterns, what you focus on is the speed of lumen decrease but not service life. Do not have excessive expectations to actual useful life.

Mistake Two: Count actual beam angle as effective angle
The beam angle of LED includes effective angle and actual beam angle. The included angle between direction of which luminous intensity values are half of axial intensity values and direction of lighting optic axis is named effective angle. The viewing angle of double half-value angle is named actual beam angle. The angle which is beyond half of axial direction intensity isn’t calculated in effective angle because of too weak light ray.
When you buy LED products or calculate the amount of LED lighting products in project, you should focus on the actual beam angle and effective angle is only looked as reference.

Mistake Three: The more power, the higher brightness
The brightness of LED is measured with luminous intensity that is a photometric quantity measured in lumens per steradian (lm/sr), or candela (cd/mcd). Generally, light source can emit different luminous flux to different directions and the visible light radiation intensity which emits from unit solid angle in specific direction is light intensity or axial direction brightness for short.
In electric power, the faster current is, the higher electric power is. However, about LED power, it is not that the more power is, the higher brightness is. 
For example, one lamp in two modes from Spark, first mode-axial direction brightness 1200mcd, current 40ma, power 0.4w; second mode-axial direction brightness 1200mcd, current 18ma, power 0.24w. From this figures comparison, we can know that the power is different in same brightness. In other words, the saying that the more power is, the higher brightness is is wrong.
When we choose spark LED lamps and lanterns, we should pay attention to axial direction brightness or luminous intensity not power.

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