Well, I finally bought a light meter. Now what the hell do I do with it? I bought a Mastech Light Meter LX1010BS. It was cheap enough and in the US, so I should have it this week-end. Right now I just want to measure throw on the Modified Defiant "C Thrower".
I think I can figure out throw from this thread, especially with this post and the simple MS calculator's sqrt button.
The problem is where? I do not want to do it in my garage, because of all the possible illumination from the walls and ceiling, side of the car, etc... Can it be done outside?
If I find a "relatively remote area", that is "dark", can I put the meter up on a tree trunk and measure any ambient light first, then measure the result from the flashlight and just subtract the begining amount, to get an accurate measurement? I actually think this would be better, because any light not hitting the meter will go on it's merry way instead of being held in a room, to bounce around. See, I want to do this at different ranges, instead of just 1m and 2m distances. I want to see how DrJones comments about throw and beam collimation work in "real life".
Any thoughts?
Then, I need to figure out how to measure lumens in a garage with absolutely no white walls. Ours are beige to begin with and after 8 years of smoking, well, I don't have to tell you any more.
No, I do not plan on making a sphere any time soon.
I think it was rdrfronty (sorry if i got that wrong from memory) who also gave a good summary recently that adds to what you found . . . he talked about using ANSI measured lights to create a baseline. That way you have a reference to use in adjusting your results to a normative value for comparison with others. If he doesn’t see this very soon, I’d suggest you PM him directly to get any advice you would find helpful.
for throw measurements under 4 meters you will find that ambient light is less than 1% of your measurement (unless you measure the throw of a small keychain light), so the garage should be fine in most cases.
Lumens I calculate from ceiling bounce lux-measurements using a light with known OTF-lumens as a reference.
Where did you get the meter at? I recently ordered on off of ebay that same model and instead of getting the 100,000 lux meter i received a 50,000 hopefully you have better luck
I sent them pictures and waiting on them to return my email it been about day and a half. Trying to be patient but its running out. It came with a tmart advertisement in it (so i assume it was one of there ebay accounts).
Even a 50K lux meter should be adequate, if measured far enough away. I take my lux measurements at 2, 3, and 4 meters indoors, and average the calculated lux. Throwers get an additional 10 meter measurement, and a 30 meter setup is upcoming.
Even a 120K lux light should only read 13,333 lux at 3 meters, or 30,000 lux at 2 meters - both well within the range of a 50K lux meter.
I purchased a 100,000 lux meter. I paid for a 100,000 lux meter. I will either get a 100,000 lux meter or I will send it back and get my money back. I will not accept a "substitute" from some idiot seller.
Please don't think I was trying to get you to accept anything less than what you paid for; I was only suggesting that a 100K lux meter may not even be necessary for our typical hobby usage.
FYI: I bought this cheap luxmeter from dx (seems to work fine, gives very consistent readings over time that could very well be right although I was never able to calibrate it). But although the highest scale is marked '50000' next to the range switch , the actual reading on the display goes up to 100000.
Well, it's a Rip Off. Ebay member "ecmonster" has sent a 50,000 lux unit. They are pulling a bait and switch, so don't buy it from them. You will get the wrong (cheaper) unit.
I have contacted them and in 72 hours (Monday), I will contact ebay and paypal about their scam.
I knew I should not have purchased off ebay. I quit using them a long time ago and never should have tried them again.
