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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971   
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Might be an idea to put a lumens rating on the advert on your website before being too critical of someone else being vague about theirs
 
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7th Feb 2016 4:20pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8582
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Looks like my work is done!
I have got people reading adverts more closely.
Yes we have missed that specification out on our web page. 
Will ask Barbara to check it out. Specification is Lumen / Lumens (LowBeam/HighBeam) 1880lm / 2400lm (calculated) ~1550lm/~1700lm (measured) We do have the full correct specification on our printed leaflets. People wanting the full specification can find it here If we have made any mistakes or omitted any key information please let us know and we will try and rectify any mistakes/omissions we have made. Brendan |
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7th Feb 2016 5:23pm |
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| Supacat Member Since: 16 Oct 2012 Location: West Yorkshire Posts: 11018 
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7th Feb 2016 7:18pm |
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| ericvv Member Since: 02 Jun 2011 Location: Near the Jet d'Eau Posts: 5816  
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How much is that in "raw" and "effective"? 
Eric You never actually own a Defender. You merely look after it for the next generation. http://youtu.be/yVRlSsJwD0o https://youtu.be/vmPr3oTHndg https://www.youtube.com/watch?v=_GtzTT9Pdl0 https://www.youtube.com/watch?v=ABqKPz28e6A https://www.youtube.com/watch?v=rLZ49Jce_n0 https://www.youtube.com/watch?v=XvAsz_ilQYU https://www.youtube.com/watch?v=K8tMHiX9lSw https://m.youtube.com/watch?v=dxwjPuHIV7I https://vimeo.com/201482507 https://www.youtube.com/watch?v=ZSixqL0iyHw |
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7th Feb 2016 7:27pm |
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| Cupboard Member Since: 21 Mar 2014 Location: Suffolk Posts: 2971
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Raw/calculated/theoretical/gross... Measured/effective/actual/net... Which is where I'm running in to problems on the Night Breaker thread. |
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7th Feb 2016 7:37pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8582
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Yes it can be confusing! Lets try a few basic definitions Watts = SI unit of electrical power = volts x amps = electrical power consumed. There is no direct SI connection between power consumed and light output or lumens Lumen is the SI unit of visible light output. OK some people argue you can calculate lumens from watts by using Lumens = luminous efficacy x watts. However luminous efficacy is not a SI unit and will vary between different LED's and different drivers etc. Raw lumens is a theoretical calculation of the light output where everything is working perfectly, the driver is working 100 % perfectly, there is no temperature rise etc This is the 100% perfect figure however in real life few things run 100% perfectly Raw lumens could be described as the 'headline' figure as it is the highest figure which the light system could possibly give out. Raw = theoretical = gross = calculated That is the simple one. If there is only one figure for light output then it will be the raw lumen figure. Effective lumens Defined as raw lumens minus theoretical losses due to inefficiencies in the driver, losses due to electrical, optical, thermal losses etc. Read this Measured lumens Get your light source and physically measure the light output by a photometric device Measured lumens is the best figure to have but not many manufacturers supply this figure. HTH Brendan LUX is how bright light is on the ground. One lux = 1 lumen per square metre or about full moon light |
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7th Feb 2016 9:32pm |
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