Zoom lights vs Reflector lights

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. :wink:

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:

  1. may have perfectly uniform flood modes with no hotspot.
  2. excellent throw in a smaller package
  3. 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:

  1. Can have both spill and spot at the same time, potentially giving more situational awareness.
  2. Mechanically simpler. Much easier to make waterproof.
  3. May be brighter (more lumens)

i don’t really like zoomed light,once had it and i give it to my grandpa :stuck_out_tongue:

I’ve never been happy with the tints of zoomies.
I don’t know whether it’s the effect of the aspheric lens (?) or what but every zoomie I’ve owned is cool white with a noticeably bluish tint (which I dislike).
I’ve tried searching all over for zoomies that come in (hopefully) 4C tints but with no luck.
What I’d really like is an xml zoomie, 2.8amps (more is better), in a 3C/4C tint.
Anyone know of any?

What is not mentioned yet is the influence of the the beam angle on zoomies, the good old XR-E has a 90deg beam angle which makes the sk68 (together with its quite optimal optical lay-out, which can not be said of most other zoomies) so effective. The most popular leds today are Cree's XP-E, XP-G and XM-L (or their mark2), and the beam angles (angle at which the light intensity has dropped to 50 % of the max) are resp. 110deg, 115deg, 120deg. (or something close to that, too lazy to check it now). So the xpe has a bit less light loss in a zoomie than a xml. However there are some leds that have a narrower angle, the narrowest I know is the Osram SSL80, which has a beam angle of 80 degrees (it has a special shaped dome). These leds perform much better in a zoomie. I have a SSL80 sk68 mod that is doing very nicely, the output zoomed out is very close to the output of a reflector light with the same led, and zoomed in gives 72% of the output of zoomed out, no other zoomie comes close to that. The SSL80 is not as efficient as the latest Cree's but that is more than compensated for when used in a zoomie.

Oh yeah good point.

Aspherics work best when as much as possible of the raw light coming out of the emitter passes through the lens instead of hitting the bezel. The narrower the beam angle the better. That said, a narrow beam angle on a low-output old LED still might not be able to compete with a highly driven modern LED with a wider angle.

Tint is completely unrelated to the aspheric lens. It’s solely due to the emitter the manufacturer chose to put into the light. If you don’t like the tint you can swap the LED in an aspheric just like you can with a conventional light. I’ve done it many times. The tint of an XML2 neutral or ZPG2 neutral looks the same regardless of whether it’s installed in an aspheric or reflector.

not true

take a zoomie w/ plastic lens that has a purplish beam, put in a glass lens, and see it turn the (still terrible but not purple) tint of the emitter whiter

not all plastic lenses have that terrible effect, but many do

My Sipik with a high CRI Nichia 219 B10 emitter shows a bit of tint shift on the margins of the beam .

I believe that plastic zoom lenses do alter the tint .

Hm. I suppose some of the cheap plastic lenses might slightly alter the beam. But not by a huge amount.

I’ve generally replaced the emitters in my zoomies with neutral tint XML2 and XPG2 emitters and the tints look exactly the same as when those emitters are installed in high-quality reflector lights. No hint of green or purple anywhere. And the zoomies I do this with continue to use their original cheap plastic lenses.

I generally change both emitter and lense

but some are much worse than others….

Zoomies have their own advantages and the most significant one is offering relatively better throw than the reflectored lights. The problems with the zoomies we have are probably due to the budget lights manufacturers refuse to make good quality zoomies for some reasons while high quality reflectored lights are very common.

I do notice the blueish or purplish tint in all of my zoomies, from SK68 clone to Romisen RC-C8 and they were ugly and this is another reason I don’t play around with zoomies anymore. Perhaps a neutral/warm/dedomed LED would looks better.

+1. I’ve owned a lot of zoomies and the tint (especially ’round the edges) has always bothered me.
The quality of glass definitely has an effect on tint, and that’s why the properties of optical glass (used in camera lenses) is so critical - and expensive. I figure cheap plastic lenses are even (much) worse in this respect.

The last zoomie I bought was just a month ago and it has this purple-ish tint that irritates me no end. But I can’t complain, since it is a cheapo one that I ordered to use as a loaner :wink:

I'm a bit confused here: It is obvious that a reflector would benefit from de-doming, as more light will be bent by the reflector. But would a zoomie also benefit from de-doming? Or would more light just hit the sides of the host and not be directed through the lens?

Then another question: would de-doming the LED in a LED Lenser light see any increase / decrease?

Dedoming increases the throw and decreases the lumens in ALL led lights. This includes both reflector and aspheric lights. It should also increase the throw in an LED Lenser… but at the cost of worse flood.

Note that dedoming also changes the tint, usually making it a bit warmer.

BanglaBob,
Yeah those bluish tint are irritating. Nevermind I am not going to purchase anymore zoomies until someone has came out a really nice quality one or one with BIG lens.

Lothar,
You may read DrJones very detail explanation here .
It’s a common misunderstanding that the beam angle of a dedomed LED would become wider and more photon hitting onto the reflector resulting more throw, in fact it is not at all because this doesn’t explain why dedoming works with aspherical lens as well. It’s some kind of internal reflection caused by the dedoming that makes the luminance (aka surface brightness) of the die much higher. It has similar effect with the Wavien Collar.

I had my Dereelight XSearcher (aspherical) de-domed last year. What used to be decent thrower is now almost in the monster-class :bigsmile: :bigsmile:
It also got quite a lot warmer, which is great :slight_smile:

I might be wrong here but dedoming a LED in a zoom setup is going to wast a lot of light. To my understanding the dome serves as a lens that bends the light and allows it to escape from the led die forward.

If only the directional part is being captured then the rest that hits he bazel is lost. In make perfect sens to dodome in a relfector. More of the light is bend by the reflector in to a beam with less flood.

Apparently there’s more going on here than that. It has been well confirmed that dedoming can give a very significant increase in throw even with aspheric lights. There was a thread last year either on BLF or CPF where the owner of OMG Lumens posted confirming it (his company makes the DEFT flashlights).

Obviously this wouldn’t be the case, if dedoming only increased the intensity of the light going to the sides and not the light forward into the lens.

I think the dome does two things:
(1) By changing the interface on the top of the die, more lumens are emitted instead of being refracted back into the die crystal. The result is overall lumens increase.
(2) It also enlarges the image of the die like a magnifying glass. Because the image is larger, the light is less concentrated… it’s harder to focus and has lower luminance…. so throw decreases.

I am not sure whether dedoming would change the light emitting angle, but I can be certain that dedoming increases throw due to the increased luminance of the die, not because of a less collimated light.

Imagine that you have a aspherical flashlight, say a UF T20. You can try to put a pre-collimation lens in between the aspherical lens and the LED. The result is you will see a larger projected die image BUT without any increment in throw. Yes, the pre-collimated lens will gather and direct more light into the aspherical lens so that they were not wasted inside the bezel, but this will only give you a higher OTF lumens NOT higher candela. It is the luminance which does the job to increase the throw (candela), not lumens to be exact.

Same goes to the LED dome. Again I don’t know if the dome is actually directing more light forward, but anyway the candela won’t be higher with a dome-on LED just because you think it should direct more light forward. The “larger” die image you see is just a perceived die size, I can simply put a 20mm pre-collimation lens in front of it and see an even much “larger” die size but that wouldn’t change the LED luminance and help in improving throw anyway.

Actually, my guess was that magnifying the image of the die with the dome actually decreases luminance, and thus reduces throw, because the lumens aren’t coming from such a concentrated area. I could be wrong though… I’m not a physicist.