I was one of the fortunate ones to get on the passaround list for the Surefire Kroma Light. A passaround is when an item is shipped to someone to test and try out, and then that person ships it to the next person on the list so they can try it also. Its a great way to checkout products, and form an opinion from actual use, before purchasing.
There has been quite alot of talk about the Kroma, even long before it came out. It sounded like a neat and innovative light, but I heard alot of mixed comments about it.
The Kroma uses the same Hall Effect rotating collar selector as the U2. With the U2, you would rotate the collar to select one of the 6 brightness levels. Turning the light on and off was done with the clickie tail switch. I really liked this concept, and found it to be very functional. I had been every day carrying the U2 for over a year, and found it to still be my favorite light. So I was excited to see how Surefire made use of this selecting collar on the Kroma.
The Kroma has a LuxIII LED just like the U2, except it is using a focusing optic instead of a reflector. There are also smaller LEDs around the optic, which I believe are 3mm LEDs. There is a set of blue, and a set of red LEDs. The selector collar position determines what set of LEDs are used.
There are 5 position: Blue-High, Blue-Low, White LuxIII, Red-Low, Red-High
The Kroma also has a different tail switch than the U2. It uses a momentary push button switch, like the ones found on the L2 and A2. With the Kroma selector collar set to the what LuxIII LED, pressing the button down half way turns the light on low mode. Pressing it down the rest of the way turns the light on high. Since this is not a clickie switch, making the light stay on permanently requires that you twistie the tail switch onto the light. Again, twisting it on half way for low, and the rest of the way for high.
That is typical operation for a two stage brightness tail switch. However, I noticed there are a few odd side effects when the Kroma is switched to the Blue or Red LEDS. If you press the tail switch half way, the colored LEDs turn on, which makes sense. But, if you press the switch the rest of the way, the White LuxIII LED will come on in high mode also. The colored LEDs will remain on. That makes it so theres always an easy way to switch to High white output, but I found it can also accidentally blind you.
Lets say you have the Kroma set to Red-Low, to conserve your night vision. You grab the light and press the tail switch, wanting to turn on the Red-Low LEDs, but you press too hard, BAM the high power LuxIII LED comes on and blinds you, ruining your adjusted night vision. This was not a big burden, but it was something to think about. There is a bit more to get used to, to efficiently operate the Kroma, verses the U2.
I personally do not like colored LEDs for practical use. Some say that red is good for retaining night vision, as it is easier on yours eyes, and they stay night adapted. But, personally, I would rather have a dim white light, for color retention. For example, if you shine a red light on a map, most of the red text and lines will actually disappear.
The beam pattern from the Blue and Red LEDs was surprisingly smooth, especially at distances over a couple feet. The white LuxIII made a very tight spot with minimal side spill, and there was a ring of light around the outer perimeter of the spill. it is typical for optics to not have a completely artifact free beam though.
However, up close, under a couple feet, the LuxIII beam was not as useful. The focused spot would actually turn into a square, as it is a direct projection of the LuxIII die. I found the wider spot, and brighter spill of the U2 to be more useful.
The Kroma is also only rated at 50 Lumens, verses the U2's 80. This is due to the Kroma using a LuxIII LED, while the U2 uses a Luxeon 5 LED. I found the U2 beam to be much more useful indoors, and it would also throw just about as well outdoors.
I also noticed that the selector collar was much easier to turn than my original U2. It also has indents at each level. I didnt mind the indents, as you can tell what mode you are on without having to have the light on. But the collar just didnt feel as solid and smooth as the original U2. The U2 is stiffer to rotate, like there is a very thick grease inside it.
All in all, I liked the Kroma, but I just didnt find its features all that practical or useful. Given the choice, I would go with the U2.
What I want to see Surefire do with this Hall Effect Collar, is make a RGB light, that smoothly changes through the color spectrum as you turn the collar. Allowing you to select virtually any color in the rainbow. The LEDs are out there that can do this, but again, how practical would this be? I would use it as effect lighting for Photography personally. But then, does that sort of light belong in a handheld?
