LED lumen equvalent to halogen

[andyfr]

I'm trying to find equivalent LEDs for our MR16 bulbs in our kitchen. When I look at the Philips bulbs we have the details are:
50W Beam: EXN 36° Lumens: 1500

When I look at comparative LEDs the details are:
MR16 High Power LED (20 piece SMD 5050, 320 Lumens, 50 watts equiv.)

How can it be as bright when the LED lumens is 320 and the halogen is 1500?

Sorry if I'm missing something basic.

 

[bernardgreen]

You need to include beam angle in the comparison.

Double the beam angle and the "brightness" at a point in the beam is reduced by 4 ( that is assuming an even spread of lumens across the area of the beam which seldom happens )

Taken from http://www.energybooks.com/pdf/D1150.pdf

Lumens
“Lumen” is the unit of total light output from a light source. If a lamp or fixture were surrounded by a transparent bubble, the total rate of light flow through the bubble is measured in lumens. Lumens indicate a rate of energy flow. Thus, it is a power unit, like the watt or horsepower.

Typical indoor lamps have light outputs ranging from 50 to 10,000 lumens. You use lumens to order most types of lamps, to compare lamp outputs, and to calculate lamp energy efficiencies (which are expressed as lumens per watt).

Note that lumen output is not related to the light distribution pattern of the lamp. A large fraction of a lamp’s lumen output may be useless if it goes in the wrong directions.

 

[andyfr]

Ahh, I see. Thanks for the explanation.

So in the example I had the LED would be a wider beam angle would it? Is it possible to get LEDs with a beam angle of around 45 degrees?

 

[Stoday]

Note that lumen output is not related to the light distribution pattern of the lamp. A large fraction of a lamp’s lumen output may be useless if it goes in the wrong directions.

You need to include beam angle in the comparison.

Double the beam angle and the "brightness" at a point in the beam is reduced by 4 ( that is assuming an even spread of lumens across the area of the beam which seldom happens )

I think you're getting lumens and lux mixed up.

 

[bernardgreen]

Lux := lumens per square metre

from the same source

unlight is about 50,000 lux. The footcandle is an older unit based on English measurements. It is equal to one lumen per square foot.

It is being replaced by lux, a metric unit equal to one lumen per square meter.

More area due to wider beam angle so less lumens per square meter meaning less lux

 

[flameport]

How can it be as bright when the LED lumens is 320 and the halogen is 1500

It isn't. The light output of the LED is significantly less, and anyone claiming it is the same as a 50W halogen is a liar.

320 lumens is dim - less than the output of a 40W incandescent lamp. (light bulb).

 

[andyfr]

Are there likely to be LEDs which are the equivalent to halogen in the near future?

 

[big-all]

as a very very rough guide a normal 100w bulb needs a 25w low energy bulb to replace it a ratio of 4times rather than the 5to 6.5 times they claim
then the same ratio applies to led bulbs off 4 to 1 so 16to1 so a 2.4w bulb will =40w

a 100w bulb = 1300 lumins my 2.4w led claims 123 lumins so would there for be around 10% the output or 10 watts but in actual fact its nearer 35w in my oppinion
now all my oppinions and observations are based on situations where normal lighting is in use no down lighters spots or fully enclosed bulbs

 

[Stoday]

Bernardgreen - I was trying to let you down lightly, but you repeated your original. So now it's the BAS method

You need to include beam angle in the comparison.
Double the beam angle and the "brightness" at a point in the beam is reduced by 4 ( that is assuming an even spread of lumens across the area of the beam which seldom happens )

Taken from http://www.energybooks.com/pdf/D1150.pdf

Lumens
“Lumen” is the unit of total light output from a light source. If a lamp or fixture were surrounded by a transparent bubble, the total rate of light flow through the bubble is measured in lumens. Lumens indicate a rate of energy flow. Thus, it is a power unit, like the watt or horsepower.

Typical indoor lamps have light outputs ranging from 50 to 10,000 lumens. You use lumens to order most types of lamps, to compare lamp outputs, and to calculate lamp energy efficiencies (which are expressed as lumens per watt).

Note that lumen output is not related to the light distribution pattern of the lamp. A large fraction of a lamp’s lumen output may be useless if it goes in the wrong directions.

Beam angle has nothing to do with the light output power (lumens) of a lamp.

The brightness of a surface, (lux) depends on the lumen output of the lamp, its beam angle, the light fitting, the reflectivity and the disposition of room surfaces.

 

[JohnW2]

Bernardgreen - I was trying to let you down lightly, but you repeated your original. So now it's the BAS method

You need to include beam angle in the comparison.
Double the beam angle and the "brightness" at a point in the beam is reduced by 4 ......

Beam angle has nothing to do with the light output power (lumens) of a lamp.

To be fair to Bernard, I don't think he suggested that it did (have anything to do with light output power). As above, he said that the 'brightness of a point in the beam' (which one would measure in lux) is a function of beam angle (amongst other things) - which, as far as I am concerned, is true.

Kind Regards, John.