Trustfire F20 Review

On AA

High = 130L - 1.8A

Medium = 55L - 0.78A

Low = 19L - 0.19A

On 14500

High = 0.97A - starts 230Lumen , sags to 210L after 30 seconds

Medium = 0.42A - 105Lumen

Low = 0.1A - 24Lumen

Mode memory is fast .... Very fast ...

Hmm, I saw those current draw numbers, by which I would calculate about 10 hours of runtime on a 2000mah Eneloop. Not too good. They seem to have upped the low mode quite a bit. My Trustfire from DX seems to be about 7 lumens on low, and the runtime is near 24 hours with a good battery.

OK taking into account this:

- The current draws (very different than mine from DX)

- The plastic protector in the clip (dx ones not have)

- The very accurate memory mode (dx ones needs several minutes to act)

- The photo of the driver (different than mine from DX)

- Hasnt failed with 14500

I can say 2 possibilities:

1) Different supplier/manufacturer than the DX ones

2) Same manufacturer as the DX ones but driver changed.

My F20 replacement should have arrived last monday but it doesnt. Tuesday was holidays in Spain, today wednesday not arrived also....

When my replacement arrive I will check if the driver is like in yours........... (if it really arrives, hope DX does not screw me this time)

Wow, didn't found F20 @ LT Only K-106 for $13,59. Will have to search better next time

Man, for less than 12 it's a good torch. And like fran, I really like the driver, hate those awful soldering. Clean driver, like on mine Kingpower. Only one question: what about regulation? On 14500 on high it drops from 230 to 210 in 30 seconds. Could you make the same test but waiting a little bit longer? Thanks

, the sag is heat related , the warmer it gets , the more output is lost , though the regulation is not bad ..

I got 200L with the battery @ 3.8v , so thats rather good . The only thing is going to be the heat , after 30 seconds the head was getting rather warm , after 1 minute I would say its going to be a bit hot .

I will see later when I have time ...

Ahms, didn't know that. Thanks for the info And the led? Really Q5? Have you checked it?

P.D.: hey, fran, are you from Spain?

I think he is and is coming from HERE. Hmm, sometimes I wish I had taken Spanish lessons instead of computer science back in school.

Haha, it's true. And Xrayboy too

Vectrex, better late than never (if you have free time)

It would seem protected 14500's do up to 230L unprotected ones much higher , lets call it 250 + ... Yeah , I think Q5

Hi SashiX, yes I am from Spain

It's the Spanish Armada ... we are surrounded.

@old4570

I have been watching your photos of the F20. The body of yours looks like to be more silver than gold.... I explain, the color of mine is brownish-gold

The akoray k-103, and the uniquefire AA-A1 are silver.

Yours?

More , of a bronze type tinge ... when compared to a Akoray or Ultrafire A20

I no longer have the Uniquefire as it was gifted ...

OK, so not silver, more bronze, brown, gold....... OK like mine

Still my replacement not arrived XP

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.