I think ceiling bounce shots are an ideal way to get a sense of total output and relative comparison light to light. Here are a few I did a while back.I've always felt you could probably devise a system using a camera with manual settings. Lots of trial and error for sure, and what to use for your standards. I'd probably start with measuring ceiling bounce differences.
Geoff
I downloaded "Light Meter" for my Samsung Galaxy S2. It works.
This program allowed me to calibrate the light myself.
I took a TK35 and placed it on a tripod at 1 meter from the sensor in the Samsung. Then calibrated it till it gave me 12 lux at 12 lumens (low mode) and 820 lux at 820 lumens (Turbo mode).
Then I tried it on the Sunwayman T20C and it gave a reading at 430 lux in the highest mode (438 lumens)
Not scientific, but fun to do
There should be a more easy way to read acurate Lumens
RichS,
Thanks for the link to your ceiling bounce shots, it is a lot of work, but payed of in the end. Probably the cheapest and most honest way to compare lights for guys like us.
EUREKA! I HAVE DONE IT! A 'BALLPARK' LUMEN MEASURING METHOD! I will smugly and egotistically claim ALL CREDIT for this method, as I have found it CONSISTENT with all my lights without further ado, here you go! (insert complementary ego stroke here)
Get some diffusers for lights of different sizes. 22mm, 26 mm, 50 mm, etc. Make sure they're quality plastic ones. I used a Kirkland water bottle at the white stripe for centering, PM if you're curious how i did it. I will be making a video soon!
I noticed that if I placed ANY of the diffusers 90 degrees horizontally centered at about 4 and 1/4 inches above the table AND put a cheap LX1010B LUX METER on the table directly under the diffuser, I could put corresponding sized flashlights into them and get a number that reads ballpark lumens. I tested this with 22mm diffusers with SWM v11r, Jetbeam PC10, Jetbeam RRT0xml, Xeno E03, and 50mm diffusers Nitecore TM11, TK41, Defiant Flashlights.
Settings on the lux meter MUST be set for x10 lux (or 20000 on the LX1010B) for anything under 1000 lumens, and X100 lux (or 50000 on the LX1010B) for anything under 10000 lumens. The number you see are the lumens you get at the x10 lux setting, and the number you see is lumenx10 at the x100 lux setting. If you see 200 at the x10(20000) reading, it should be understood as 200 lumens. If you see 200 at the x100(50000) reading, it should be understood as 2000 lumens. I have yet to build a good standing rig to make sure all diffusers remain level and such, but if you wanted a quick and dirty way to do it, this is IT.
Here are some 'lux lumens' I get from my method:
TM11:
Low: 205 david luxlumens
Medium: 535 david luxlumens
High: 1119 david luxlumens
TURBO: a whopping 2190 lumens! (fully charged cells of course)
TK41:
Low: 14 david luxlumens
medium: 110 david luxlumens
high: 325 david luxlumens
Turbo: 765 david luxlumens
Sunwayman v11r IMR:
Turbo: 482 david luxlumens
RRT0 IMR:
Turbo: 525 david luxlumens
Jetbeam PC10 IMR:
Turbo: 487 david luxlumens
Klarus ST20:
Moonlight: 2 david luxlumens
Low: 13 david luxlumens
Medium: 123 david luxlumens
High: 240 david luxlumens
Xeno e03 NW xml AA:
Low: 6 david luxlumens
medium: 40 david luxlumens
high: 94 david luxlumens
Thrunite TiS aaa
Single: 66 david luxlumens
Defiant 5c 650 lumens:
semi drained cells: 573 david luxlumens
IT WORKS! Please go test it for your self. I have finally contributed something awesome for the layman at CPF!
I agree that my method is in NO way scientific, but merely coincidental. However, the numbers that come up seem to match the manufacturers' 'ansi' ratings...upon 15-30 seconds of initial activation, anyways. I want to do a video with a stand, but have not yet secured a stand on which to mount everything uniformly. I'm thinking of using a chemist's test tube holder stand thingy with different sized clampsI think this is akin to the ceiling bounce method in principle, but scaled down to concentrate the light on a smaller more proximal target. The weakness of the ceiling bounce has always been the tendency to over represent hot spots, as more light is reflected straight down at the meters by the central part of the beam on the ceiling, and to underestimate the corona and spill portion of the output at more peripheral areas that are proportionally less likely to reflect back at the meter.
The other weakness for all home made/DIYS devices is the calibration of the meter itself. If the meter is accurate to +/- 10% for example, your lumen measurement cannot be more accurate than that either, as its a limiting factor. So a reading of 1,000 Lux could have been ~ 1,100 or 900 lux for example.
Of course, meters have scales, and, are more accurate in some parts of the scale than others. Typically, mid-scale readings tend to be more accurate, with the accuracy falling at the upper and lower ends of the involved ranges.
If you don't trust the ANSI #'s, and I have a sneaking suspicion that some are NOT done with NIST certified IS equipment, etc....then its a way to at least get a feel for how close they might be...and, its a way to benchmark modded lights, etc.
The issues that could complicate matters would be:
The distances, as the lux drops according to the inverse square law, so a small difference in distance to the meter sensor will have a large impact on the calculated lumens. So the distances would require careful calibration to be applicable as apples and apples for different test runs, etc.
I'm looking forward to your video!!
EUREKA! I HAVE DONE IT! A 'BALLPARK' LUMEN MEASURING METHOD!
IT WORKS! Please go test it for your self. I have finally contributed something awesome for the layman at CPF!
Good for you.... whatever diffusion method you use, you quickly get a sense of its accuracy by testing a variety of your own lights against the manufacturer spec - and IMHO, your own results will be far more accurate and consistent than what I've seen claimed by certain manufacturer's "ANSI FL1" specs. Those rules have holes wide enough to drive a truck through, not to mention the conservatism the humble manufacturers employ.
I personally use a horizontal bounce (between two walls in a narrow hallway) for diffused sampling, but have also tried the white plumbing pipe method with the same results (piping the light through two 90-degree elbow bends).
Don't forget to reconcile with Selfbuilt's results where you can, although I use a significantly more conservative lumen scale than he.
Do you have any Zebralight AAs you can test?