(prototype) the GT Mini

Mine is a 17ā€round sphere, calibrated using maukka lights, using a drmeter. Itā€™s got two baffles preventing direct exposure on the meterā€™s sensor. Using an HS1010a at 20ā€™ for the candlela.

Same exact measuring setup reads 2008 start lumens (1886 at 30s) on the catapult v6, with 174kcd.

Also took a hotspot pic at 4 feet. Both on low settings. GT mini is NW, v6 is CW.

Blf gt mini vs catapult v6 hotspot

The gt is a good deal smaller. Measuring on the wall, I got about 3ā€ on the mini and about 4.5ā€ on the v6.

Just tested the mini again with vtc5a, and got 1057 at start and 1013 at 30s.

Hereā€™s a few pics of my sphere, for reference:

New sphere

edit: just bypassed the driver spring with 20ga and got 1195 at start and 1081 at 30s. Also stretched the spring out a little and about 2 coils had been soldered together at the board side. Spring popped right out and gave about 7mm of height, compared to about 4mm out of the box.

The Decapitator centering ring will find your weak reflowā€™sā€¦.right click on pic, view image, + to enlargeā€¦nice rotational scissor action going onā€¦. :smiley:

Never like that style of centering ring. :rage:

Sorry to hear about the smoke problemā€¦thats the second person to have that happenā€¦hope you get it fixed.

I did get mine delivered yesterdayā€¦FINALLYā€¦Heres my unboxing video

Email sent to address. Thanks

Still nothing for me :person_facepalming:

Now USPS has removed the estimated delivery date completely, and the last update is still from the 22nd when it was processed in New York.

nkresho, wondering about how you figure your lux readingā€¦ if you do it at 20ā€™ what is the math on that? I ask because I was told to use EXACTLY 5M (or 10M or 15M or more, Iā€™ve done up to 50M), then multiply the meter reading by 5 squared (25) to get the lux reading. So if itā€™s a multiplier of the distance squared, what do you use as a multiplier x meter reading? (just checking to see how you derived that lux number) 5M of course is 16.4ā€™. It would help if we all used a standard distance, but of course throwers actually need some space to get the beam focused properly if theyā€™re any good at being throwers, so a 5M reading may be cutting the lux short.

Using this in excel: =(0.09290304*T22*20*20)
with T22 being the cell with the lux reading.

Meter is in a dark room, in my basement, on a black metal cabinet. Meter reads 0 at test start, with ambient light.

Measurement is 20ā€™, via tape measure to a fixed point on the ceiling, with a thumbtack and a long rubber band hanging to where I hold the light.

I test for 30 seconds and have the meter set to display the max number (this might be where iā€™m off). Reading peak rather than the 30s number.

I measured my GT (bone stock) at 30ā€™, and used =(0.09290304*S21*30*30) for that one. I got 1.151M candela in that instance.

What is the 0.09290304 number? Not sure why the two lights, at different distances and power levels, would have a same multiplierā€¦

Ok, say youā€™re at 16ā€™ 4.8ā€ distance (5M) and you shine a light at the meter which reads 10,000. Youā€™d multiply 10,000 x 25 for 250,000 as a lux reading (250Kcd) and then take the square root of 250,000x4 for throw. (1000M throw)

Another light, weaker, shows 767 on the meter set at 10x, so 7670 x 25 = 191.75Kcd. Taking the square root of 191,750 x 4 youā€™d get 875.79M throw for this one. See? nowhere is there a same multiplier except for the distance squared (5M squared is 25)

I donā€™t know all this part well enough to understand why weā€™d have a different formula, which is why Iā€™m asking. :wink: Trying to discover how we all get on the same page.

Woohoo!! Got mine in the mail last night just in time for some night work on a movable bridge. This GT-Mini is tinyā€¦ smaller in hand than expected. Slightly shorter than my Nitecore P30 (by 0.5 inches/12mm) but the head/bezel diameter is nearly the sameā€¦I put them face to faceā€¦ but the head size of the GT Mini is smaller than the P30. Just got to get used to the side switch on this little bad boy (Iā€™m used to the dual-switch on the P30- Tail for on/off with tactical momentary-on and side switch for mode/levels).

Most likely mentioned before but UI is similar or same as BLF Q8.

The only bad thing I have to say about it is that this is a minor dimple in the reflector 10:30 oā€™clock position (looking at LED with switch at 12 oā€™clock position) about halfway in between lens/bezel and LED. It doesnā€™t affect the output or quality of the beam but it is a minor defect. It is very noticeable because the rest of the reflector is near perfectly smooth (the lateral machine lines on the Nitecore P30 are way more noticeable). It sticks out like a sore thumb.
Is there a way to request a replacement reflector?

Iā€™ll figure out a way to post a pic.

I wish I could see your pictures, but they are not showing up. Your sphere sounds a lot like the ones from Josh K. Is that what you have or is it just similar to it? Not the same at all.

Keep in mind that the Catapult V6 uses an xhp35 Hi which is a bigger LED than xpl Hi.

Iā€™m guessing the 0.09290304 number is about converting feet to meters. Candela is always meters.

By far the easiest way to measure it is try to find 10 meters in your house. It doesnā€™t need to be completely dark or anything. Just subtract whatever the ambient light is from your total reading. I typically set my light down so that the emitter (not lens) is at the 10 meter mark from the sensor (meaning 1ā€ from the wall). Then I turn on the light and walk over to the opposite wall and try to find the area of the hotspot that is brightest (I measure along a straight line between the center and the edge of hot spot). It can sometimes take 25 or 30 seconds, so I just kind of count that out in my head. Once you have the number at 10 meters the math becomes very easy. You take whatever that number is and multiply by 100 which is just adding two zeros to the end.

So my GT Mini was 1,480 lux. This is 148,000 candela at 1 meter. Easy math. My big GT was 10,560 @10m which is 1,056,000 cd. 10 meters is the way to go if you have the space.

Then to convert to distance is the regular X4 then square root.

Mine thrunite v6 measurement are similiar to nkresho. If that is true, mini gt cw have more lumen than nw ā€¦ i was told mini gt cw led are high bin. anyone can verify ?

Hereā€™s my formula reference:

Lux to candela calculation with distance in feet
The luminous intensity Iv in candela (cd) is equal to 0.09290304 times the illuminance Ev in lux (lx),
times the square distance from the light source d2 in square feet (ft2):
Iv(cd) = 0.09290304 Ɨ Ev(lx) Ɨ (d(ft))2

Source is here: Lux to candela (cd) conversion calculator

Sorry, hosted to imgur, since photobucket and imageshack are garbage nowadays.

My sphere is a semi-copy of the ā€œmatch sphereā€ Started with a ~17ā€ bouncy ball, paper macheā€™d it ovfer and over for a few weeks, then did a few layers of fiberglass for strength. Cut it open, sanded the inside and painted it with BaSO4. Two baffles using pingpong balls, also BaSO4 coated, were added. One to catch direct light between the source and the sensor, and a second to catch the primary reflection directly opposed to the source. It uses an interchangeable light plate similar to the newer TA tube design, so each plate can be the right size for the light and I can swap them easily. They are also BaSO4 coated. Sphere is also calibrated with Maukka lights and have a variable multiplier correlated to color temp. Warmer lights get a slightly lower multi, due to how my DrMeter reads.

I think you are making your calculations way more complicated than necessary. I would just use a simpler method such as 10 meters. Thereā€™s no need to reinvent the wheel.

Itā€™s all in a spreadsheet. I just plug in the lux reading and it does it by itself.

I work in excel all day long at work. Itā€™s only complicated once.

But, if itā€™s not accurate (the math involved), I am happy to change it up.

Very nice unit. :+1:

Thanks. Sheā€™s kinda ugly, but does the job well as far as I am concerned. Lumpy like a big black meatball on the outside. Was so sick of paper mache-ing that I didnā€™t really sand the outside to a body shop quality finish like I originally planned. Business end (inside) is baby-butt smooth.

I canā€™t understand what your saying here. Are you saying that the Mini GT cool white has more lumen than the Mini GT neutral white?
Where does the Catapult V6 fit in?