jar3ds said:
the Surefire U2...its basicly a flashlight without throw nor spill.... which are very important for a flashlight...
I definitely disagree. The U2 has
tremendous spill, you could argue maybe even too much.
The U2 beam has a central hotspot, no corona and an unusually bright spillbeam. At 1/2 the spillbeam radius it's about
five times the lux of my HDS U60 and Streamlight TL-3. The flashlight designer must apportion the available light energy between spillbeam, hotspot and corona. The U2 puts much more overall energy into its spillbeam than the central hotspot. By contrast other flashlights put more into the hotspot.
At first this would appear to adversely affect throw, yet the U2 throw is pretty good. It's not a super-thrower, but at 50 yards range with my TL-3 hotspot focused to the U2 hotspot size, the more powerful TL-3 doesn't visually appear that much brighter. Of course the TL-3 can be focused to a smaller spot and in that configuration will throw much further.
The U2 hotspot beam angle is about 6 degrees, so it's not excessively broad. The spillbeam angle is about 60 degrees, so at 2 feet, spillbeam is 27 inches diameter. By contrast my HDS EDC U60 has a spillbeam angle of 70 degrees, and my TL-3 is 100 degrees. So the U2 spillbeam is a little narrow, but very bright.
In summary, the U2 has a very cleverly designed beam pattern which blends the best characteristics of a pure flood light like the L4, yet retains reasonable throw. This is appropriate for its intended utility role (hence the "U") designation.
Imagine if you instrumented your flashlight with an ultrasonic or laser distance measurement device and data acquisition system, which logged the distance-to-target over a period of time. For most users, you'd find the distance to target is usually in the shorter-to-medium range. The U2 is ideal for the most common usage that the average user encounters.
However if the intended usage is over a body of water, or on a large, flat rural property, you probably want a more throw-oriented light.
The upcoming HDS/Novatac lights look interesting. The LT (Long Throw) version appears to have multiple output levels like the U2, but with a longer throwing reflector.