Newbie here, Question about candlepower

[wwwdotanthony]

Hello all, I have a flashlight used on Boeing airplanes, and the spec rates it at 4700 Candlepower @ 7v DC. I need to know is there a light meter that measures candlepower; and if not, is there a way to convert candlepower output to footcandles or lumens.

 

[labrat]

Google, and you will find:

http://www.theledlight.com/lumens.html

 

[nerdgineer]

4700 candlepower means it should put 4700 footcandles of light onto a surface at 1 foot distance (at beam center) or 4700 lux of light onto a surface at 1 meter distance. Light meters measure light level landing at a surface (in footcandles or lux) so (for footcandles and candlepower) you have to multiply footcandles by the square of the distance in feet to get candlepower.

Lumens is the total amount of light output by the light in all directions and requires measuring the light in all directions with a math conversion factor or an expensive instrument which can do this automatically.

Oh, and welcome...

 

[wwwdotanthony]

Thanks guys..

 

[LuxLuthor]

Depends on how much time you want to spend, but with all due respect, the information presented in this thread thus far is both incomplete and partially inaccurate (especially once you have moved to measurement of an actual light with reflector like you use on Boeing). General statements are often made about the various light terms and attempted conversions between them--in an attempt to simplify and be helpful.

Here are a couple resources to read at your leisure.

CPF Post on subject​

International Light Technologies FAQ

Wiki Resource on Lumens

Useful XeVision FAQ page

Ryer Light Measurement Handbook (3.6mb PDF file)
​

 

[Juggernaut]

At least it has a realistic CP rating as a note: to you wwwdotanthony , if your new to this hobby and you see one of those 1,000,000 CP lights sold in local hardware store, they really are not 212 times more powerful then your light:thumbsdow.

:welcome:

 

[yellow]

always thought that planes have a higher bord voltage, like trucks or so (24V) or even more
:thinking:
wouldnt this make for less current --> smaller wires (weight) or less heat in wires (safety)?

 

[nzgunnie]

Standard aircraft power is 28VDC or 115V AC 400Hz.

 

[BlazerBud]

You can't describe a light without giving more information. I will die of curiosity.
What brand is it?
What does it look like?
Do you have a picture?

 

[wwwdotanthony]

Sorry bout the delay.. Here's the link to the CMM for the flashlight

www.dmecorp.com/services/download.asp?productid=12

Technical data on page 20.. Flashlight has its own battery supply, so its not running off airplane voltage, which nzgunnie is correct on.


:edit: Also, Im looking for a good low-priced radiometer probably in the 10k fc/lux range so I could try and test this output for myself. Any suggestions?

 

[lctorana]

Interesting that it looks like a 2D light, but runs at 7V falling to 4.5V.

That suggests lithium batteries, doesn't it?

And the beam size at 25 feet suggests a very deep reflector.

 

[mdocod]

I'd guess it uses a 5 cell NiCD pack or something to that effect. 1.4V fresh from charger per cell, 0.9V is the usual termination point of a discharge for a NiCD or NIMH cell.

 

[cougar_67]

According to the pdf it uses 10 alkaline manganese dioxide cells in serial-parallel config.









Steve

 

[Mr Happy]

According to the pdf it uses 10 alkaline manganese dioxide cells in serial-parallel config.

Yes indeed. It uses 5 x 1.5 V alkaline cells in series to give a nominal 7.5 V, and it uses a standard PR-18 pre-focused bulb, 7.2 V, 0.55 A. In terms of lighting performance it is unexceptional. It would be exceeded by a 5 cell MagLite.

All of the enormous cost of the light has gone into the design and construction to make it foolproof and compliant with regulations. Overall the cost of the light is probably 90% red tape and 10% engineering.

I think it has curiosity value but little technical value.

 

[Taboot]

Yes indeed. It uses 5 x 1.5 V alkaline cells in series to give a nominal 7.5 V, and it uses a standard PR-18 pre-focused bulb, 7.2 V, 0.55 A. In terms of lighting performance it is unexceptional. It would be exceeded by a 5 cell MagLite.

All of the enormous cost of the light has gone into the design and construction to make it foolproof and compliant with regulations. Overall the cost of the light is probably 90% red tape and 10% engineering.

I think it has curiosity value but little technical value.

Never underestimate the effort (time and cost) of engineering a foolproof system, even a simple seeming one.