Manufacturer:- www.metermantesttools.com / www.oka.com.tw
Retail Price :- £46.50 $88.50 http://www.xe.com/ucc/
Size:-170mm long, 44mm Wide, 40mm Deep
Weight (With Batteries):- 220g (7.76oz)
Battery Type / Qty :- 4off AAA
Battery Life :- 200 Hours Typical on carbon zinc cells
Body Material :- Plastic
Finish :- Gray
Overrange: - (OL) is displayed
Low Battery Indication:- Symbol on display
Measurement Rate ;- 2.5 times per second
Operating Environment :- -20 to +60 Deg C
Accuracy :- at 23 Deg C + or - 5 Deg C
Total accuracy :- for CIE standard illuminant A (2856K) + or - 3%rdg + 10dgts
Peak Hold Response :- >50mS pulse light.
Range :- 20lux, 200lux, 2000lux, 20000lux - 20fc, 200fc, 2000fc, 20000fc
Resolution :- 0.01lux, 0.01fc
Spectral Response :- CIE photopic
Acceptance angle :- 150 Degrees
Analogue Output :- 0.1mV/counts Positive on the centre pin
Manufacturers Guarantee:- 1 Year

This is something that I finally got round to buying after wishing to compare the light output of my growing torch collection. I did not buy it as a super accurate laboratory instrument but as a more accurate guide than the human eye to light output.

In this task it performs well and it is reasonably easy to use.

First some Maths :(

Not to worry all will become clear

10.764 footcandles = lux (Lumens/meter squared)
0.0929 lux = footcandles (lumens/foot squared)

Rather than go on about measurements etc I will point you at an excellent web link on the subject.

http://www.led.net/pages/tech4.htm

All we need to understand is how to take measurements of our flashlights and compare these with other people / other flashlights. More later on. First lets look at the hardware.

The Meterman LM631 / Tecpel 531 Lightmeter are essentially the same thing. I will assume that they are made in the same factory and re branded for various companies.

It comes in a nylon pouch which will serve to protect it and keep the dust and grime away from the sensor.

The meter has an illuminated LED display, Off / lux / fc selector switch for selecting your preferred measurement units and three pushbuttons.

The pushbuttons can be used to select the following:-

HOLD. holds the display reading (Useful if you want to photograph the display after measuring a light output.

PEAK. puts the unit into peak hold mode to capture the brightest light reading. Holding this button down for two second will illuminate the LED display back light.

RANGE. pressing this button cycles through the range selections. You will see the decimal point move when you do this. On the highest range X10 will be displayed meaning you should multiply the displayed measurement by 10 to get the true reading.

The back of the unit has a removable battery cover. Please note that this is retained with a small cross head screw. Removing the screw allows the cover to be removed for access the four AAA batteries. Battery life is quoted at 200 hours. I don't know if this is accurate as I am still on the first set that came with the meter! I would imagine that using the back light has a big impact on battery life.

The sensor is mounted to the top of the unit via a flexible cable that allows you to detach it so you can get at inaccessible places where the rest of the unit would not fit. The light sensing part of the sensor is fitted with a plastic dust / lightproof cap. It says in the instructions to replace this after use to preserve the sensor life. I assumes that this means that bright light will eventually degrade the sensor. Not a problem as most torches are reasonably low powered compared with say sunlight. So it should last a long while.

The base of the unit is fitted with a mono jack plug socket to allow the connection of an external voltmeter or data logger. I have not used this yet but would like to in the future. Perhaps when I acquire a nice logging Fluke multi meter for a sensible price.

In use I switch on to the lux range. Then set the range. The latest Luxeon III lights need the highest range as we are well into the 2400 lux @ 1M range. I measure lights by placing the light meter on the carpet and placing my camera tripod above set at 1M distance. This makes it easy to rest your hand on the tripod and move the torch beam around to achieve the highest reading.

I think this has helped to put several of my lights into perspective and is a great way of measuring similar lights that to the naked eye look the same. It is also great to test new batteries and things like PILA cells that can have a lower voltage to see if the light output drops etc.

This is an essential gadget for any serious torch collector / enthusiast.

Manufacturer:- www.metermantesttools.com / www.oka.com.tw

UK Sales :- www.digital-meters.com

More info this and other lights related fun here

www.candlepowerforums.com

www.britishblades.com