Got a Lux meter - Can you guys help me 'calibrate' it?

I have just received my lux meter from eBay, just a cheapy, the LX-1010B.

I have taken some readings at 8m and converted back (take the reading, times by the distance squared, so x64 in this case). The readings below are what I have obtained on charged, quality cells. I’d like to know what you guys have measured so I can see if I need to add a correction to my readings. The readings are done indoors down my corridor with as much daylight shut out as poss (reads 0 on most sensitive setting without flashlight).

Roche F12 2.8A NW - 4.5K
L2T MF 5mode OP - 6.4K
BLF A8 - 9k
Jetbeam PA40 - 9.1k
L2P with 2.8NW intl dropin - 9.7k
HS-802 Red - 15.9K
Trustfire 3T6 2cells - 18.6
XinTD v2 C8 NW - 19.2K
Nitecore EA4W - 21k
UF980L - 21.1K
UF C88 2A driver - 30.1K
MPP1 1xCell - 35.2K
UltraOK 2A driver - 37.1K
Jacob A60 - 41K
MPP1 on Gladiator with 4x cells - 53.1K
Crelant 7G5 V1 - 60.2K
FatMaxVN - 87k low
FatMaxVN - 356k high

Any suggestions on improving my results and comparisons appreciated :slight_smile:

Edit to add Fatmax

A corridor might not be a very good place, since it’s likely that the luxmeter catches some reflections from the walls/floor etc. Depends on what is on the floor/walls.

Yes I did wonder that, the floor is carpeted but it’s all light tones. I will retest a couple outside and compare, it’s just very convenient indoors.

I am sorry to say this but I don't own even a single one of those lights

Wish I could be of more help here. Even more so after your great Thrower thread work for the forum. That one is epic :-)

No worries mate, thanks for the comments and help in that thread :).
I’m thinking my readings are just a touch high but not far out. My Jacobs should be here soon and I’m trying real hard to resist a STL to de-dome, ala the de-dome thread, I just can’t do that to my Crelant…… Anyway the more I add the better of an idea I’ll get how close I am.

That's true. Hope someone chimes in soon with some numbers for you :-)

Just added the Jacob, bit disappointed with the 41K as i thought it outshone the MasterPiece Pro 1 from solarforce but its seems not. Mine draws 1.4A from a charged Panasonic and a protected 3100 Xtar so maybe a bit underdriven compared to others. Still it makes it my best single cell thrower as the MPP1 needs the extra voltage.

Just saw this and am sprry to hear you received one that is not up to par out of the box.

I have 3 ideas for you though.

1 is to use a unprotected battery. It loves those.

2 is to tighten the driver screw in plate in the bottom of the head. Mine drew around 1 amp initially but got it up to about 1,8 when I was finished working on it. I actually ended up putting a ring made of thick solder wire (2,5mm) under that driver screw in plate that also holds the batt + plunger in place. That really helped but I think 1mm solder would have been just as good. I made it so it was tight against the threads of the driver cavity and touched the driver's negative contact ring. The metal part of the driver crew in plate then touches this and helps to make better electrical connection to the body.

3 is to unscrew the head and then really push hard on the little plastic retainer disk that sits over the led base down hard. That makes the thermal path better.

Hoping for the best.

Thanks mate, I tried a unprotected Panasonic but it was the same, i will try the other two suggestions tho, sounds like its worth a try. I do have another on the way as I ordered two separately, so I hope the second one will draw a little more.

Edit: Just saw your measurement at 10m from the A60 thread, not too far off, mine at 41k and yours at 44.6k.

ive got a uniquefire c108 which is a c8 type light. it is modded with a 2.8a nanj driver and a ar coated glass lens.
readings were taken at x10 setting
2m = 561 = 22440@1m
3m = 271 = 24390@1m

also, my nitecore ea4w consistently reads at 17300-17400 cd. which i think might be on the low side. maybe its the lithium primaries im using in it?

edit: im also not sure how accurate my light meter is, so may not be much help :frowning: