Thanks Tom E! I think I found the problem.
I had a feeling that the problem is with the K40 reflector so I tried to compare the performance of the K40 and the D01’s reflectors using the D01 body (and emitter). Here’s the set-up:
First I used the D01 reflector set-up like above and took the readings at 6 meters. The highest reading I got after all focus adjustments was 6030 lux or 217,080 cd.
Next, I used the K40 reflector set-up like above and repeated the whole process at 6 meters. The highest reading I got after all focus adjustments was only 3180 lux or 114,480 cd.
So my I guess my theory is true. The K40 reflector is NOT as good as the cheap D01 reflector. My K40 is an old model originally with an XM-L.
Here’s a closer look at the two reflectors:
The K40 reflector at the left is deeper than the D01 reflector at the right and it is just a bit narrower so all other things equal, it should perform better if not at par with the D01.
Here are the front ends of the two reflectors. What I noticed is that the K40 reflector is dark where the D01 reflector is bright colored and this could be the culprit. Much of the light from the LED could just be absorbed instead of reflected forward in one direction. Also, not obvious is that the K40 reflector is like a cross between an SMO and an OP reflector while the D01 reflector is 100% SMO.
For comparison purposes, the Vostro BK-FA01 reflector is also bright colered like the D01 reflector and this could be the reason of the Vostro’s and the D01’s more than 200 kcd compared to my K40’s 182 kcd max.
To further confirm that the K40 LED is not the problem, I reassembled the K40 and took the readings at 6 meters, and I got 4650 lux or 167,400 cd. Compared to the 3180 lux using the D01 body (and LED), the 6.1 amp current of the K40 has indeed driven its emitter (an XM-L2 T6 1A) farther than the 4.4 amp current of the D01 (XM-L2 also).
Are the reflectors of your K40s similar to mine? :quest: