You only get 0% reduction by using a led that has a die with the same luminus intensity as the XHP35 Hi. These leds exist (XP-L Hi, dedomed XP-G2, and Oslon Black Flat have even higher luminus intensity and should throw further) but have usually smaller dies so you loose output instead of gaining it. There is currently one led that gives the same throw combined with higher output, the Luminus CFT90, but it is not very efficient, it is a 3V led so it needs a new driver, it needs some modding get it fit and centered, and perhaps most significant it is a really expensive led, like over 100 dollar.
Let me correct the throw distance I used before. I thought it was 2200m, but it looks like itās 2000m. So going from xhp35-HI to a hard driven stock 70.2 is a 40% throw reduction. The sliced dome has a 20% throw reduction.
Anyway, a larger diameter emitter is almost always going to decrease throw because itās hot spot is larger. The xhp35-HI emitter die is about 5.5 square millimeters. The xhp70.2 die (dome on) appears to be about 22 square millimeters due to the roughly 40% magnification effect of the dome. (I think itās 40% to 50%). Anyway, thatās a huge increase in emitter size.
Slicing the dome off makes the die about 15.7 square millimeters. Thatās still 3 times bigger than the xhp35-HI.
On the other hand, a larger emitter can usually be brighter which then gives you back a lot of the throw distance you lost.
With the sliced dome 70.2 emitter doing 6,000 lumen instead of 2,000 lumen, the net result is a small 20% loss in throw.
You could go with a smaller emitter to get more throw than stock, but itās a pretty small hotspot and was voted down during the GT design phase.
If you want more than 2000m throw along with a bigger and brighter hotspot, the CFT90 is the hot ticket. When pushed really hard, it can give about 2450m throw and 4500 to 5000 lumen (according to Skylumen). So the hotspot is a little bigger, itās much brighter and the throw is increased. Sounds great! Whatās the catch? They cost about $675.
The bottom line is a lot of folks donāt really need to see 2000 meters (1.2 miles). You can make the GT more practical with a 70.2. It doesnāt cost much more and it can still throw a long way, plus you get a much bigger hotspot to better see what your looking at.
BTW, all xhp50, 50.2, xhp70, 70.2 emitters have domes.
Keep in mind that VOBās numbers were a fair amount higher then mine. He was using a P2 bin emitter vs my 4000k 80cri. So it is possible we are both correct. Since he has before/after numbers it is hard to argue the relative performance gains of his numbers.
I ordered 8 x35Eās before I ordered my gt , I havnt got them yet & I didnāt use the contact form because I bought them separate (on neals deals) , Iām using 30Qās now so Iāll probly just ask for a refund , but Iāll be happy to get the batteries instead of a refund , Iāll see what Neal says.