Only ten years ago, it would have seemed silly to talk about a flashlight having a user interface. Press button=on, press again=off. That was the extent of it. Most lights had one mode and one thing to do with the switch, toggle between on and off. But newer lights have more modes and features. Some, like the Klarus XT10, have two switches, one for on and off and the other to change modes. It is not a bad solution, but it is not ideal either. So then, what is the perfect flashlight UI?
Yep, another picture of my two favorite pocket companions and my old iPhone 3GS (I have since involuntarily upgraded to the 4G after my wife's was stolen...what a fiasco). The Haiku has a pretty outstanding UI. I have struggled for while to think of anything I like better. I like the two stage twisty of the Muyshondt Aeon too, but in the end I think the McGizmo gets it right. So why is it so good? Simplicity, responsiveness, and customizability are the three best reasons.
First lets look at other UIs. Fenix has a UI that many other makers use. In most Fenix lights (the TK35 being the exception because it has a Klarus-type dual button set up), the tail switch activates the light AND changes the output mode, but in order to get certain other output modes, such as a super bright high, you have to twist the head. It is neither just button presses or twisting to get you where you want to be. The problem with this set up, in my experience, is threefold. First, it requires a lot of inputs to get to a specific mode and more inputs means more potential for error. Second, it requires two totally different forms of input and this means that you have to have two hands free and it prevents quick and easy cycling. Third, because it requires two hands or at least one hand doing two different things there is a possibility that in emergency situations some of the modes would be inaccessible.
Then there is the Piston Drive system. For more on that, check on the Arc6 review. There are two kinds of PD systems, one is a momentary on and twisty. This is the system used on all of the McGizmo PD lights and the Arc6. The Nitecore Smart PD essentially functions like a clicky. Problem here is a little more subtle. Again in the momentary on configuration, the light requires two different movements to access everything. I like the momentary on, but it is, in everyday use, not that helpful. The second problem is a bit more of a nagging concern instead of an outright failure. The PD offers very little in the way of feedback. A good clicky has both a sound and feel that goes together to tell you exactly when you have activated the light. The PD instead has a metal cylinder being depressed and that is it. Not a big deal, but if I had my choice, I'd go with a clicky every time.
Then there are the click, double click, and press and hold UIs used on the Novatac and HDS lights. They are, again, good because they are clickies, but they are WAY too complicated. What is the difference between a click and a press? How long do you have to hold for a hold to count? How fast is too fast for a click to count in the double click sequence? Some of these lights even have triple click activations which is sort of ridiculous. They are just too complicated for use in emergencies or by non-flashlight people. I am sure that long time users have all the subtle presses down pat, but I would like to use my flashlight not have to memorize how it works. the Liteflux with its clicky and two different UIs is the worst offender in this group. It can, if mishandled, result in NO output.
Then there are the twisty lights. Generally speaking I like twisty lights. They are a bit harder to use one handed, which is why I prefer a clicky, but they are so close that a well done twisty is better than a mediocre clicky. I really like the two stage twisty on the Aeon as it is minimizes actions required to access modes. The twisty on 4sevens MiNi series is a lot of movement to get to high or a TON of movements to get to a hidden mode. I like the low-med-high set up of the MiNis and I like the hidden mode better than the dual UI, hidden programming mode on the Liteflux, but it is still a lot of twisting and moving. I like the Preon version of this UI, with a clicky. It does very well and would fall into the next category.
Then there is the Surefire two stage and Serac S3 three stage clicky. These are getting very, very close to the mark. In these UIs you simply press the clicky to turn on, usually in low, and press again to turn off. If you press again quickly you will get the next level until by doing this you cycle back down to low. These are simple UIs that you can use easily and other, non-flashlight folks can use as well. They are almost right. The only problem is that if you don't like the output sequence your stuck. If you want your light to come on on high, there is nothing you can do but cycle through until you get to high. The lack of a mode memory means that you will always start out at the factory preset and if you don't like that, well tough luck. Still, for EDC use where the output sequence is not so important, this is a great choice. The Serac S3 is especially nice because of the good output levels and the ability to bump up from one level to the next without having to do a full on/off cycle.
Then we get to the Haiku's UI. It is, in my opinion, perfect. It is simple, responsive, and customizable. First here is how it works. Click once on the amazing McGizmo clicky (which are so good they are sold as aftermarket upgrades for other lights) to turn on in low, then again to turn off, quickly after that once more to get medium, and again to get high. It is very similar to the Serac S3 UI. But here is the difference that makes it better. It has mode memory. If you turn the light on and then off and it is in low, the next activation, even if it is a year later, will be in medium. This allows you to "set" the output sequence. If you want your light to come on in high you can simply cycle through before turning it off so that the next activation is on high. If you want it to come on in low, you can do the same thing. You can change the order of the sequence but you can change where in the sequence you are when the light starts up, giving you a bit of customization. All of this is done through a single well-design button.
Compared to everything else, the Haiku is just too perfect to ignore. It is easy enough to hand to a non-flashlight person and have them use the light. There is no fear of accidentally dropping into a programming mode like with the LiteFlux. It is also responsive. The clicky kickback and sound are unmistakable. Not loud, just consistently there. And finally, with the simple mode memory, you can change the light to come on in at any level you want.
Two caveats. First, if the outputs themselves are not well chosen, the UI doesn't really matter that much. You want well spaced outputs with a very low low and a high high. I like a 5%-30%-100% setting for the outputs so long as the high is above 120 lumens, otherwise the two lower modes are different enough to be useful. If the light hits more than 500 lumens, then I would like to see at least four output modes: low low (sometimes called moonlight mode), a medium low, a high of about 100-150 lumens, and then screaming high of 100%. Second, I have not had a chance to use the Spy UI which is a knob on the front of the light that both turns on the light and selects output. Similarly I have not tried the Rotary HDS light's UI or those of other rotary style lights. I think they are nice and intuitive, but again, I thing twisting is a bit worse than clicking because it usually requires two hands or some serious finger yoga. The Surefire Titan T1 and T1A seem to be the best of the bunch as they are just twist lights--twist for on, twist more for brighter. No button and twist.