Yup. Too many people think that multiple levels, strobe, etc. are automatically "features" that always add usefulness and never take away.
Nobody said anything about strobe. In nearly all implementations strobe is far more trouble than it's worth IMO. But variable brightness is very useful if implemented well. The problem is that it's very often implemented poorly.
Not so: you lose the ability to have a big fat button that you can press and get the light you want, every time. The more complicated the UI, the worse this penalty is.
A flashlight with the UI of the Photon Freedom would satisfy this. Click on/Click off, 100% output guaranteed. Once on, if you want to reduce output (say to conserve battery life) click and hold. If you want to start low and ramp up, say to fumble throug a bag, or walk through a dark theater, or navigate around a dark beach without disturbing others, click and hold while the light is still off to start at LOW and ramp up as needed.
The only true multi-level light (more than 2 levels) that I like is the Surefire U2. You can crank it up to high--by feel alone--and then almost forget that it's a multi-level light if you want. The Fenix L1T/L2T v2.0 has this advantage, too. I don't really care for multi-click lights, unless it's just two levels like the Surefire E1B.
Dedicated controls are a very good thing -- ie, the switch is on/off, the dial controls brightness. True "random access" multi level brightness. IMO all "big" lights should have a dedicated brightness control. I will say though that I have never liked interfaces like the Fenixes where the on/off switch is used to "step through" different levels, particularly not when there's no way to go from high to low directly. The LxD series that switches from high to low by tightening the head is at least tolerable in that respect.
One of the advantages of multi-level output is the ability to save battery life. With the current generation of LEDs, this ability matters less than it used to. For example, the 2007 version of the E2L puts out 50 lumens for over 9 hours in regulation. Even the 2008 version will run for 6 hours regulated on its 80-lumen high beam.
This is a good point, although the reason I prefer low levels has little to do with battery life (though that is a nice bonus). One of the big reasons why many consider LEDs a good choice for multi-level is that they get more efficient when dimmed. A more significant benefit IMO however is the fact that they maintain their color temperature at all outputs. If oyu were to dim an incan to say 0.2% output, it would be a useless red, and still be consuming a huge amount of power to produce a lot of IR. With an LED, at 0.2% output , the spectrum is still essentially the same, and the batter life could be as much as 700x longer on a set of batteries (effectively forever...)
90% of my real (non showing off) flashlight use is from a Liteflux LF2x on its lowest setting, about 1/3 lumen. If anything I'm finding that to be too much in many cases. Runtime on a AAA at that output is 2 weeks of on-time.
I recently did a worskhop where we were developing red-sensitive holographic film in pitch black. The only light we used was a blue LED, run on a single 2032, with a couple layers of filters over it to block spill reduce output even further. It was producing perhaps 1/100th of a lumen at most, but it was enough to see what I was doing, keep from tripping, etc.
The following are the different sorts of UIs I'd use for variable brightness, depending on size:
Coin Cell -- Photon Freedom
AAA Keychain size -- ie AAA lights -- LF2 interface, essentially a programmable two stage. Set the highest level that will run for 30mins, a low low, and never use anything else.
EDC Size -- ie AA up to "slender" 2CR123 lights, like the P3D. Photon Freedom interface. Using a signal level swtich instead of a mechanical switch could make the tailcap a lot smaller and more reliable.
Large Size -- Basically, A dedicated on/off forward clicky, and a dial with brighnesses increasing from a fraction of a lumen, to maximum logarithmicaly.
At very minimum, I believe most lights larger than a keychain should have a LOW low output (~0.1%), medium -- for battery conservation (30%), and high (100%). Specialized lights, such as those used in REAL tactical situations by Police/Military, may still be better off as single level for simplicity.
