Hi again, old. One question: do you test the flashlights the same way Don does? I mean, can I use your lumen info and compare it to other Dons lights that he reviewed?
Cant compare against anyone else , sorry ...
We would need a universal test that would come at least close , so that we could be at least + or - 10% or so ...
But there are just too many variables , such as the light meters themselves ... We would need some sort of system of calibration , and thats going to cost $$
So unfortunately , I dont see it happening ....
So unless you used the same Light box , light meter , battery , flashlight , your not going to get comparable results ..
You can calibrate with any specific light and just make sure the boxes reasonably resemble an integrating sphere with a laser.
For example, you check your box with a cheapo pointer at different angles, ship him the laser, and do the same there.
--
I've also been thinking of another way to do lumen measures with only a camera. It should be possible to integrate the image projected on a wall/flat plane (subtract a the dark shot and do geometry/addition on the rest) provided the sensor is not in saturation. As long as the angle to any point is known, easiest if the camera is right by the light, it should be possible to calculate a relative unit. Then cal that unit against a known light.
With manual exposure and RAW files, it's relatively simple in theory.
Another followup idea would be to do a simplified version of this. Assume that either led light hits the reflector or goes out the front, either of which is reasonably uniform. Then you need at a minimum these measurements:
1. Hotspot size in degrees
2. Hospot intensity in lux and degrees measured from center
3. Flood size in dregrees
4. Flood intensity in lux and degrees measured from center
Still need calibration from the unitless numbers from this.
Not really sure if that's going to be accurate, but can't be too far off.
Only need 3-4 above for zoom light in flood mode.
None of that sounds simple , nor doable from one end of the world to the other ...
Too many variables still ...
One way would be to test the output of a light + battery combo ....
Then ship it to some one else so they can take measurements .... Lux in one light box = Lux in other light box = Simple ... But still variables
For example, you check your box with a cheapo pointer at different angles, ship him the laser, and do the same there.
This isn't too hard. I believe it's close to the simplest possible to get consistent results.
--
The other idea is just a way to get lumens without a lightbox, or even a lightmeter.
Hi guys, I received now the replacement of my TF F20. It was destroyed on 13 september after using a 14500. DX shipped the replacement on 23 SEPTEMBER!!!! and arrived today.
All I have to say: DX version SUCKS. Purchase the LT One. And the LT one is even CHEAPER....
Why purchase the LT one instead of the DX one?
The replacement I received has the SAME driver board that the one that broke with 14500, so I will not put a 14500 on it. The driver board that I am talking about is the one which has a "red path joining 2 parts of the circuitry" clearly visible in the part where the battery makes contact.
The LT one works perfectly with 14500, the driver looks very different and includes the plastic protector in the clip. Meaning that DX and LT have different suppliers for the same product..........................
ERROR 404 - PAGE NOT FOUND
Oops! Looks like the page you're looking for was moved or never existed.
Make sure you typed the correct URL or followed a valid link.
All your images are dead, Matt 
Not only in this review, but in other too.
Picture host is gone .... I need to take new pictures ...
But it looks like it will be a lot of work ...