Yup. One advantage of zoom lights is that they allow a whole lot of throw in a very compact package…. typically more throw than you could get with a compact reflector light. The downside is that the large portion of the beam that hits the side of the bezel when the light is in spot mode is usually lost. Typically, the smaller the lens and the further the focal point, the more light will be wasted inside the bezel.
A few observations on zoom lights:
1. All budget zoom lights work by having a simple aspheric lens in front o the emitter. Move the lens and emitter closer together for flood mode and increase the distance so the base of the emitter is at the focal point of the lens for spot mode. Most budget lights do this by mounting the light on a sliding sleeve. Some lights have the sleeve threaded so it unscrews. Others have the lens fixed in place, but have the LED star mounted on a moving platform controlled by a turnable ring or even a motor.
2. The closer the lens can retract to the top of the emitter, the larger the lumen output of the light and the wider the flood mode. Ideally, you want the back of the lens almost touching the emitter. Many budget zoom lights don’t allow the lens to retract far enough leaving a useless “flood mode” that feels like you’re shining your light through a toilet paper tube. It is often possible to mod these lights for much improved spill. Anything that lets the emitter sit closer to the back of the lens in flood mode works. I’ve tried all of the following mods, and all work to improve flood:
(a) file down the sides of the body to allow the sliding bezel to retract further.
(b) file down the top of the pill to allow the bezel to retract further.
(c ) add copper or aluminum disks below the star inside the pill so that the LED sits higher up in the pill.
(d) add a shallow plastic reflector inside the pill around the star, to help capture some of the wasted output and direct it through the lens. (gives much improved flood mode with a broad hotspot and eliminates almost all the rings caused by light bouncing around the inside of the pill. Downside is in spot mode you’ll get an ugly halo around the spot.
3. Higher the surface brightess, the better the throw. In order to get maximum throw you need an emitter with high luminance (surface brightness). Think of surface brightness as lumens per square milometer. Smaller emitters tend to have higher surface brightness than larger emitters. However, larger emitters will produce more lumens due to their larger surface area. This means if you want maximum throw in something like an SK68 you should stick to a small emitter like an XRE or XPE2. Switching to larger emitter such as XPG2 or XML2 will usually produce a wider, dimmer spot.
However, because the small emitters produce fewer lumens, if you pick the smallest throwiest emitters, you’ll get a weak flood mode. If you want great flood mode you’ll need a big emitter like an XM-L2… but you’ll get it at the cost of a mediocre spot mode. If you want great spot mode go with an XPE2 … and have weak flood mode. If you want a compromise, go with an emitter in the middle like an XPG2.
4. When performing any mechanical mod that adjusts flood mode or changes the emitter, it may be necessary to refocus spot mode onto the focal point. It may be necessary to add spacers made of bent strips of aluminum or copper around the top of the pill to allow the bezel to extend further, etc.
5. LED Lenser - It’s possible to make a zoom light that has virtually the same lumen output in both flood AND spot modes. This is done by having a carefully engineered lens or lens/TIR with a pocket in the center that wraps completely around the LED in both flood AND spot modes. This requires that the LED be mounted on a raised pillar instead of a conventional flat star. Since all light coming out of the LED is gathered by the lens/TIR regardless of which position the bezel is in, total light output doesn’t appreciably change.
Unfortunately for us modders, the patent on this mechanism is owned by LED Lenser. The only brands to use this system are LED Lenser and Coast (done presumably with license from LED Lenser). No budget lights use this mechanism… even the budget lights that look like LED Lensers don’t use the optics of an LED Lenser…. instead they all use simple aspheric lenses.
6. Wavien Collars -Instead of losing light into the bezel of an aspheric light in spot mode, a small reflector called a wavien collar can be added to reflect that light back to the emitter. This increases the luminance of the die by further exciting the die to emit more light, and by reflection as some of the light reflects off the top of the die into the lens. Wavien Colllars are used in the Deft-X to dramatically increase throw.
I don’t know of any zoom lights using a wavien collar, but see no reason why it couldn’t be done. Mount the LED on a 10mm star on a post, then have the wavien collar attached to the bottom of the sliding bezel/lens assembly. When the lens is retracted for flood mode, the wavien collar would also slide back out of the way around the post allowing for a wide flood … someone on BLF should try making one.
7. De-doming - one way to increase surface brightness is to de-dome the LED. If done right, this reduces overall lumens (so flood is worse), but increases the luminance so you get a smaller more intense hotspot in spot mode. From what I’ve read, the most effective way to dedome the resin lens on an XPG2, XPE2, or XML2 is to soak it in gasoline and then push the softened lens off.
8. Recoil thrower - most reflectored LED lights mount the LED at the base of the reflector. However, some lights mount the LED on an arm at the front of the light near the lens. The LED is mounted backwards so it faces into the deep reflector. This type of reflectored light is called a recoil thrower and can produce similar or even superior throw to an aspheric. A downside however is that because the LED is mounted on a small arm, it is very hard to dissipate heat so a powerful or overdriven emitter probably isn’t practical.
9. Zoom lights and water resistance - forget about making a cheap zoom light waterproof. In most cases it isn’t practical. Most budget zoom lights work with a silding bezel/lens assembly. Moving the bezel changes the physical volume of the light. If the light is airtight, air pressure inside and outside the light will want to equalize. This will cause the bezel to slide on its own back into the position it was in when the battery tube was sealed. Vacuum action may also cause the light to suck in water past the o-ring if it is cycled underwater.
To insure smooth one-handed zooming operation, small zoom lights should purposely be left not watertight so that air pressure can equalize. This can be done by leaving off one of the o-rings near the bezel.
Advantages of zoom lights compared to reflectored lights:
- may have perfectly uniform flood modes with no hotspot.
- excellent throw in a smaller package
- No spill, so you won’t be lighting up things you don’t want to. Especially helpful when looking at things in spot mode, as the spill from a reflectored light on things in the foreground may blind you to things in the distant spot.
Advantages of a typical reflector light:
- Can have both spill and spot at the same time, potentially giving more situational awareness.
- Mechanically simpler. Much easier to make waterproof.
- May be brighter (more lumens)