I did some testing of my Dorcy 180 Gen IIs and my UK MiniQ40 eLED Plus last night, and took a couple of photos with the camera built into my computer. Unfortunately, I was only able to set the lights up about 70" away from a wall, so some of the details of the beam shape were lost, and the camera lacks exposure control so I couldn't adjust it to make the details come out better. And for some reason I'm having trouble importing them here. I tried to attach them but not sure it worked, so will describe them if that didn't work.
The first photo showed the two Dorcy 180s side by side. One of them has a very well defined hotspot, which under water within 6" of a white surface can be seen to be a blacked-out square with extensions straight off each side, the side furthest away from the square being rounded. The other light head has a larger, less well defined hot spot, a few of the lobes are visible, but the hot spot is more of a blob, especially underwater. This appears to be due to less precision in manufacturing, probably normal variation.
The second photo showed the Dorcy with the wider spot side by side with the Q40 which looks very washed out in comparison. After taking this photo I moved to where I could shine the lights on a wall from about 10' away, to see more detail of the beams. The Q40 has a hot spot that's roughly 2.5 to 3 times the diameter of the Dorcy. It's a warmer (lower temp) color, not as bright, and there's only a single, much lower brightness ring at roughly double the radius of the hot spot. The 180s have multiple rings,at least four well-defined ones with others, that extend out as far or farther than the Q40 does, each ring being of lower brightness.
For the photos the Dorcy with the wider spot had six new Duracell Copper Top Alkaline AAAs, the other one had two new Copper Tops and four that have been sitting in my freezer unused for a year or more. The Q40 had 3 Energizer alkaline AAs and 1 Kirkland alkaline AA, and I've used these batteries for an unknown length of time in this light, but probably less than 1.5 hours total.
After taking the pictures I decided to get some new AAs for the Q40, and noticed some increase in brightness but no change in color temperature. I swapped light heads on the Dorcy, so that the light head with the tighter spot was now on the body with six new batteries.
Both the 180s had been used intermittently for about 15 minutes up to this point since I installed the batteries. I turned on the one with the tighter, whiter, brighter beam and 6 new batteries (Dorcy #1) on and left the other one (#2) off, only turning it on briefly whenever I compared it to #1, and put both of them in a plastic dish tub with enough water @ 50 deg. F. (a typical water temp for Monterey) to cover them, then left them. After about 40 minutes the water temp had increased to 54 deg., so I put the tub in the refrigerator for another 20 minutes, which brought the temp back down to 50. For the rest of the test I kept the water temp between 48 and 52 deg. by making use of the refrigerator when necessary.
After 1:00 hr constant burn time, #1 was now slightly less bright and appeared to be a slightly lower color temp than #2; that may just be an effect of the drop in brightness. I let #1 run for another 30 minutes.
At 1:30, #1 appeared to have lost a bit more brightness, but the difference was very slight.
At 1:45, there was no difference from previous levels that I could detect.
At 2:00 hr. there was again no detectable change, so I reverted to checking every 0.5 hours.
At 2:30, same.
At 3:00 hours, #1 was either the same or may have decreased slightly in brightness, but was still plenty bright.
At 3:30, no detectable change.
At 4:00, maybe slightly dimmer.
At 4:30, no detectable change, and time (2:00 a.m.) for me to go to bed. But first, I took all three lights outside and shined Dorcy #1 against a dark fence from about 10 feet away, side by side with the Q40, then shined them all three of them in turn on the top of a tree 50-75 feet away.
The difference in beam width and rings was very apparent on the fence and the tree. The Q40 has a large hotspot, and even though it has a single ring extending beyond it there's virtually no usable light in it -- almost all the light is concentrated inside the hot spot. It lit up the entire top of the tree, perhaps 15 feet wide.
The Dorcy's had smaller, brighter, whiter hot spots than the Q40 initially, but #1 appeared to be about the same brightness and color as the Q40 after burning all this time. Both provided more useful light outside of the hotspot than the Q40 did on the wall, but the tighter hotspot only lit up about half of the top of the tree. Dorcy #2 was noticeably brighter and whiter than the Q40 or the long-burning #1, but the latter still provided more than enough light.
All in all, I'm quite pleased with the performance of the Dorcy, but still need to get them underwater with my Q40 and my friend's DR500 to see how they do in that environment. I've previously used the Q40 as a primary at night, and have found it to be pretty decent at that. Judging by the run time I achieved at ~ 50 degrees, it should be possible to use rechargeable batteries in the Dorcy lights and use them as daytime primaries for signaling and crevice-viewing, at least. I intend to find out, but don't have rechargeable batteries and a charger yet. I'd still prefer that the lights used AAs like the Q40, which is about the same size.
Guy
I vote for visible and unmistakable, over cool
