Check out this HID tourch
20-09-2010, 10:51 PM
#8
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The relationship between Lumens and Candelas depends on how the lense/reflector system works and how it was measured.
An isotropic (equal light in all directions) 1Mcd lamp would emit 4*pi*1M lumens = roughly 12M lumens.
An isotropic 4000 lumen lamp would emit 4000/(4pi) cd = roughly 333 cd.
However, torches are not isotropic. If they measure the brightness in a 2-degree hot spot then:
1Mcd * (2*pi*(1-cos(2degress/2))) = 1Mcd * ~0.001 = 956 lumens.
Whereas if the 4000 lumens torch were equivalently focused:
4000lm / (2*pi*(1-cos(2degrees/2))) = 4000lm / ~0.001 = 4.2Mcd
An isotropic (equal light in all directions) 1Mcd lamp would emit 4*pi*1M lumens = roughly 12M lumens.
An isotropic 4000 lumen lamp would emit 4000/(4pi) cd = roughly 333 cd.
However, torches are not isotropic. If they measure the brightness in a 2-degree hot spot then:
1Mcd * (2*pi*(1-cos(2degress/2))) = 1Mcd * ~0.001 = 956 lumens.
Whereas if the 4000 lumens torch were equivalently focused:
4000lm / (2*pi*(1-cos(2degrees/2))) = 4000lm / ~0.001 = 4.2Mcd
21-09-2010, 07:00 AM
#11
The relationship between Lumens and Candelas depends on how the lense/reflector system works and how it was measured.
An isotropic (equal light in all directions) 1Mcd lamp would emit 4*pi*1M lumens = roughly 12M lumens.
An isotropic 4000 lumen lamp would emit 4000/(4pi) cd = roughly 333 cd.
However, torches are not isotropic. If they measure the brightness in a 2-degree hot spot then:
1Mcd * (2*pi*(1-cos(2degress/2))) = 1Mcd * ~0.001 = 956 lumens.
Whereas if the 4000 lumens torch were equivalently focused:
4000lm / (2*pi*(1-cos(2degrees/2))) = 4000lm / ~0.001 = 4.2Mcd
An isotropic (equal light in all directions) 1Mcd lamp would emit 4*pi*1M lumens = roughly 12M lumens.
An isotropic 4000 lumen lamp would emit 4000/(4pi) cd = roughly 333 cd.
However, torches are not isotropic. If they measure the brightness in a 2-degree hot spot then:
1Mcd * (2*pi*(1-cos(2degress/2))) = 1Mcd * ~0.001 = 956 lumens.
Whereas if the 4000 lumens torch were equivalently focused:
4000lm / (2*pi*(1-cos(2degrees/2))) = 4000lm / ~0.001 = 4.2Mcd
21-09-2010, 10:33 AM
#13
20K+ Super Poster.
Makes me laugh, torches with spots that can go so far, can your eyes pick a person out at 1km away hidden in trees ?
As a search and rescue torch it is a TOTAL failure, run time no where near long enough, light excessively bright when it doesn't need to be, piccies are fakes.
The sheer size of the thing if you're crawling around in the woods, a much dimmer function with a longer run time would have been better.
4000 lumens is nothing to shout about for something of this size/price, my ssc p7-c de puts out 900 lumens with a 2 hour run time on high 5 hours on low(360 L) yet is about 8" long light as a feather it's been dropped run over by an astra and still works 100% perfect best bit £16.
tabetha
As a search and rescue torch it is a TOTAL failure, run time no where near long enough, light excessively bright when it doesn't need to be, piccies are fakes.
The sheer size of the thing if you're crawling around in the woods, a much dimmer function with a longer run time would have been better.
4000 lumens is nothing to shout about for something of this size/price, my ssc p7-c de puts out 900 lumens with a 2 hour run time on high 5 hours on low(360 L) yet is about 8" long light as a feather it's been dropped run over by an astra and still works 100% perfect best bit £16.
tabetha
21-09-2010, 11:59 AM
#14
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Makes me laugh, torches with spots that can go so far, can your eyes pick a person out at 1km away hidden in trees ?
As a search and rescue torch it is a TOTAL failure, run time no where near long enough, light excessively bright when it doesn't need to be, piccies are fakes.
The sheer size of the thing if you're crawling around in the woods, a much dimmer function with a longer run time would have been better.
4000 lumens is nothing to shout about for something of this size/price, my ssc p7-c de puts out 900 lumens with a 2 hour run time on high 5 hours on low(360 L) yet is about 8" long light as a feather it's been dropped run over by an astra and still works 100% perfect best bit £16.
tabetha
As a search and rescue torch it is a TOTAL failure, run time no where near long enough, light excessively bright when it doesn't need to be, piccies are fakes.
The sheer size of the thing if you're crawling around in the woods, a much dimmer function with a longer run time would have been better.
4000 lumens is nothing to shout about for something of this size/price, my ssc p7-c de puts out 900 lumens with a 2 hour run time on high 5 hours on low(360 L) yet is about 8" long light as a feather it's been dropped run over by an astra and still works 100% perfect best bit £16.
tabetha
21-09-2010, 08:38 PM
#15
got this one first http://cgi.ebay.co.uk/ASU-SSC-P7-900...item45f53585c5
then got told about this one http://www.dealextreme.com/details.dx/sku.44459
So will see how they perform
The one from deal extreme has got some good reviews, its a copy of a light my friend has apart from his was around £700 new believe it or not
he didn't pay that tho as he is a manager of a bike shop.. but still £700
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