things to settle when you have a dislike for aspherics

I am not a huge fan of zooming aspherics, well, ok, I hate them: in flood modus the beam is too even (I like a beam more intense in the middle, that makes sense because that is where you want to look), in throw modus they are plainly ugly and they throw away most of the light inside the body. In contrast: reflector lights have nice smooth beams with more intensity in the middle where you want it, and a spill with weaker light for an idea what else is going on (and most of the light that is produced actually does make it out of the flashlight!).

Unfortunately I own two aspheric lens zoomable flashlights. I bought them to find out what the fuss was about them. It is a 18650 xml brandless zoomie (similar to the later marketed sipik 98) and recently a xre-zooming headlight. The latter light was throwing well, but was so unusefull (even modding appeared impossible, but that is another story) with far too much throw even in flood modus, that I came up with the idea that has improved the head lamp, and is explored further in this post.

This is the light I took for the experiment; it had been (rightly so) sitting under a pile of flashlight hobby junk for months till now:

(My advice:just don't buy xml flood-to-throw lights (even not the beautifull z8), the spot brightness just does not increase considerably when zoomed in, but you do get that hideous led projection.)

First thought was to make some diffuser to help improving the beam.

But then, what the heck, I'm not married to this horrible light, why not diffuse the lens itself? And there I went. Best would be to diffuse the inside of the lens (with sanding paper), because by doing that the outer curve of the lens still does its focussing, giving more intensity towards the center of the beam. And next step was sanding the lens again with finer sand paper and later polishing with ordinary copying paper to make it back into a clear(-ish) lens, making beamshots and ceiling bounce luxreadings along the way. Here is some pictures of the abused lens in several stages:

Here are the beamshots for the six chronological stages of the process in flood modus and zoomed in (unfortunately two of the flood beam pictures were accidently deleted, but you get the picture anyway). Flashlight and camera were 1.70 meters from the wall, camera settings were all the same: iso125, f3.5, 1/40sec. The images give a reasonable idea of the beams, although you will never catch the full spectrum of light intensities with a camera.

First zoomed in: 1-before sanding, 2-sanded with 400 sanding paper, 3-sanded finer with 800 sanding paper, 4-polished with plain copying paper, 5-light sanding again with 800 sanding paper, 6-polishing again as well as possible with copying paper.

Now 4 of the six stages zoomed out:

So this went well ! , sanding the lens magically turns disgusting beams into beautiful beams. Personally I like situation 3 and 5 best, some of the zooming ability is still there, and zoomed out there is that beautifull beam, gradully dimmed out towards the edge (the pictures do not justice to how nice the beam was).

And what happened to the total light output? Everything is relative (just like real life), so when the output before the experiment zoomed-out is stated as 100, all other readings are given relative to that:

original output zoomed-in is 55 (ouch), stage2zoomed-out: 78, stage4zoomed-out: 89, stage5zoomed-out: 76, stage6zoomed-out: 84. Then I discovered that the battery wasn't full anymore (later readings should therefore be interpreted a bit higher than measured) so recharged the battery and after that stage6 was back to 100.

The readings zoomed-in were in line with the zoomed-out readings when taken relative to the initial zoomed-in reading (of 55).

The output readings summarised: you do not loose an awfull lot of light when the lens is diffused like this, if done with care you loose only 15 to 20%.

Conclusion of the experiment: if you own any one of those ugly zoom-to-throw flashlights (now I am going to have it in this BLF-world full of Sipik68-devoties ), there is hope, you can turn its beam into something really nice

only zoom-out so far and get a beam (hotspot/corona) of your liking? H) H)

The Coast HP550 here recently appears to do just that. I have no doubt if its mechanism were allowed to zoom further out I’d be seeing an emitter at 100 yards instead of nice big hot spot.

I might have to try that with the Z8. I regret the emitter swap now. After I threw in an XML T6 3C, the hotspot is really yellow while the spill is nice and neutral when unzoomed. Zoomed in, everything is fine, ofc..

When zoomed out halfway the diffused hotspot of a zoomie is still square-shaped.

But well, it was just an experiment I did not have too much expectations of, but went fairly well to my surprise , so i thought let's make it into an aspheric-polemic

The HP550 and an UltraOk ZS-2.

The ZS-2 has zoom travel of 1/4” or 16/64”.

If I zoom-in to 13/64” I get basically a very-near perfect circle.

So I guess it depends on what zoomie ya got. 8)

I put an o-ring in between the zoom-in stop and head on one of them to auto-limit travel to get a nice round diffused-looking hot spot. I guess for me having the quick ability to just roll the o-ring over the stop and get full emitter throw was an option I wanted to retain. But I understand your approach and I think it’s innovative factoring in your choosing of a custom-expanded diffused spill as well. I get very little spill with mine.

Perhaps this also hinges on a particular aspheric’s degree range.

So I have the two worst zoomies in the world . Oh well, then I may grow into them at some stage

(and now to bed, too late already...)

speaking of different zoomies, the HP 550 for instance has very little spill adjustment latitude. It’s pretty much zoom-out all the way to get one BIG even spill or zoom all the way in for throw. Anything in between and ya get pretty much a big halo ring with a dark circle in the middle. 8)

Good job!
I have some diffuser films of two “stages”. I think I should try yhem with zoomies since I believe they eat only like 5-10% of the power.

Ah, I looked up what flashlight the CoastHP550 is, now I underdtand, it appears to be the Led Lenser type, which is optically a bit different from a aspheric, it is more of a zoomable TIR, with a raised led, I believe the optics are still patented by Led Lenser. I have the LL M5 (with XRE in it), and that one also has rather good looking throw-spot.

Good to understand that they did their optical trick with the xml-led also, thought they would not be able to do that.

is even a quasi-TIR. AFAIK, it’s my understanding that true TIRs aren’t zoomable, period. I may be wrong in that understanding but then again I don’t mess much at all with aspheric modding either. The only other standard-looking aspherics I have is the ZS-2’s, Sipik68 clones. If the HP550 lens design were instead on ZS-2’s I guess I’d still have trouble groking the TIR connection as I know it. :nerd_face:

The HP550’s lens consists of about a 1” diameter dome which is about 1/4” in height surrounded by a concave perimeter which is about 3/8”. The overall lens measures I’m guessing about 50mm. The head screw-in part sure doesn’t come apart using my grip-gloves and putting all my oomph into it.

My understanding of an aspherical is one like the 50mm lens I have for a MagLite. I can hand-hold it over any torch and adjust distance from the led and get various results. If I try that with a true TIR as we tend to know them (that being statically-placed over an Led), I will most likely get an aberration.

So is the HP550 lens a zoomable quasi-TIR , is it a hybrid aspheric, or is it actually in reality an aspheric with a concave perimeter? H)

Just sayin’……

Nice job! I prefer #3 zoomed in and #5 zoomed out. :beer:

I agree with the op, the die image bugs the crap out of me, I have one zoomy, and if it wasn’t so useful zoomed out I’d give the thing away, its 2 x 18650 so its not even that attractive to most flashaholic’s. Definitely my most regrettable buy. :expressionless:

Here’s some suggestions from my experiences modding my Sipik SK58 zoomable:

1. Mod the light for wider flood - One problem a lot of zoomable flashlights have is that the flood mode simply isn’t wide enough. Depending on the model of the flight in question, there might be a relatively simple mod you can do to dramatically increase the width flood.

The problem is this: On many zoom lights, in flood mode the lens stops a considerable distance from the top of the emitter. The closer you can get the emitter to the back of the lens the wider and brighter your flood will be. In my SK58 I made the following modifications to accomplish this:

(a) the sliding bezel retracted towards the back of the light until it was stopped by the raised square-cut knurling. I filed down around 3 mm of this knurling so that it was flush with the portion above it. This allowed the bezel to retract further than the stock light.

(b) I took a thin aluminum strip cut from sheet aluminum from my local hardware store. I bent this strip into a ring and inserted it around the threads at the top of the pill. Now when the pill is screwed in it stops when it hits this ring. The fully inserted pill doesn’t sit as far back in the body, and as such sits closer to the lens in flood mode. This change also allows the bezel to extend further in spot mode. A second thinner strip can be added outside the first if necessary to add a hard stop to achieve the correct focal distance.

© The pill itself had a considerable amount of metal projecting above the surface of the emitter. This extra material prevents the lens from retracting as far back as desired. I filed this down so the emitter would sit closer to the top of the pill.

2. Flood mode isn’t bright enough: No reflector means the flood beam is very smooth and uniform with no bright hotspot. However, sometimes this isn’t desired. Personally, in my zoom lights, I prefer a wide smooth hotspot rather than no hotspot.

To fix this problem, and to insure maximum possible OTF light in my modded SK68, I added a small reflector. The reflector serves to catch light that would otherwise reflect off the inside of the pill in flood mode and direct it out the front.

I took a smooth plastic reflector from an old AAA Underwater Kinetics (UKE) halogen lamp module, by using a hobby saw to saw it off just below the base. Then I used a drill to widen the center hole to accomodate my XM-L emitter. I removed the fins around the edges of the back of the reflector. I then glued the reflector onto the white plastic retaining ring that came with the light, and which was originally used to hold a metal washer around the emitter (I used arctic alumina epoxy).

The reflector from a 2xAAA Maglite also works quite well for this task and is probably a lot easier to obtain than the lamp module for an UKE light.

This did a few things:

(a) Instead of a perfectly uniform circle with no hotspot, I now ended up with a wide flood with a very wide hotspot. My light has an XM-L installed and the new hotspot was at least 1/3 to 1/2 of the entire flood. This gives a very wide useful hotspot for close-in work. The hotspot looks significantly brighter than flood with no reflector installed and provides dramatically brighter and more useful light. The reflector I used is very small and didn’t come focused for the emitter at the focal distance it was set at. That’s ok. The purpose of the reflector was to provide additional flood, not a perfectly focused long-range hotspot.

(b) Like many zoomies, the SK58’s flood mode projected a number of bright unpleasant rings around the outside of the flood circle. These rings are caused by reflections off the interior of the pill. The reflector almost completely eliminated these rings in flood mode.

© In spot mode, the focal point is close to the surface of the reflector. This results in a rather ugly image of the reflector projected around the image of the die. Not a big deal for me and not noticeable when used outside to look at something in the distance. A smooth reflector will produce a less ugly ring.

3. Consider de-doming. As an experiment, I tried a dedomed XM-L in my light in place of the domed T6. This had the following effects:

(a) very noticeable increase in lux in spot mode. The image of the die was much smaller, but also much brighter. It looked about the same size as the image from an XP-G, but running at 2.8 amps appeared far brighter.

(b) signficant decrease in overall brightness in flood mode. With the reflector installed, the main thing I noticed was that instead of a floody hotspot that took up most of the total flood, I ended up with a significantly smaller hotspot in the center of a wide flood. Flood mode looked much more like the flood from a conventional reflectored non-aspheric flashlight.


Personally, I decided to stick with the domed XM-L because usually I’m using my lights up close and the extra lumens were really nice. For my zoomable EDC, I prefer a light with great flood that “just happens” to have the ability to shift to spot mode to see stuff in the distance. Spot mode may not be that bright, but it is still far better than a typical reflectored flashlight of that size.

I’m running the light on a 2.8 amp Nangj 105c driver custom-programmed by Dr. Jones with an electronic switch. I’m using an XM-L T6 5,000k neutral emitter from CNQuality goods.

Yes, the die image is ugly.

On my modded SK58, I used strips of aluminum bent in rings around the top of the pill threads to fine-tune the focal distance in spot mode. Instead of stopping right at the die image, my lens extends just past that point. This is sufficient to unfocus the die image slightly so that the lines on the die disappear from the image, making the entire spot into a barely larger slightly fuzzy square. Any reduction in lux from doing this was unnoticeable.

wow, that sounds like a solid piece of work! I like the reflector idea, going to have a go at that as well! Thanks for the extensive post.

I intend to fix the problem by leaving out the cells and keep it to remind me “wot I dun wrong”. :frowning:

Zoomies are just a poor compromise and really you never get the best of either world. Instead it's the worst of both worlds. Personally I don't care for square die, but after doing a large aspheric, I can see that an aspheric will out throw a reflector and for people who love throwers, I can see going with a large aspheric thrower, but for the best throw I would go with a HID.

Most of the small zoomies I have tried have way too small of an aspheric lens for an XM-L. They are much better off with a small die led. XM-L needs a 50mm+ aspheric (I feel) and smaller ones are a waste. The ultimate flood to throw does not exist. They are two different beasts. Now maybe one could go with one body and two heads. That would be closer to a one light fits all.

Some good modding ideas for zoomies have been posted in this thread.