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scootle
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"Clover" artifact in beam pattern

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This may or may not be an item of note for folks regarding the actual beam pattern... there is a slight artifact in the beam center at close range due to the lens design (which I presume is normal).

Image here (beam in "low" mode for clarity): http://imgur.com/dZX6I

When you crank the beam into higher power modes, the artifact is still there, but the beam is bright enough that it "washes out" significantly if you try to look for it.

Edited by: scootle ( )

In addition to the "clover" artifact, my beam pattern also exhibits a slight off-color blue/purple tinge to the center spot at distance (something my other high-output lamps from Fenix and Surefire do not exhibit)... there is definitely something a little off with the TIR lens assembly on my unit. I can't speak to whether or not this is endemic to the design, but people may want to be aware that things aren't completely "perfect". That said, for TIR design, the spill/flood properties of this particular TIR are impressive... many lens-based designs tend to be too focused for general purpose use... this one is a good balance. I am not implying any of this is necessarily a fault... just points of information. :)

scootle,

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David Hilton
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Turn on your light and screw/unscrew it and you'll see it change.

I've only noticed this when the flashlight is partially unscrewed.

I see what you mean. I don't find it terribly noticeable at more than 6 inches. It seems to be an artifact of the cree led being square, under a couple of circular lenses.

David Hilton,

Light was definitely tightened down... I'm not saying this is a "bad" thing per se... at range the pattern disappears... but compared to some of my other high-output LED lights using reflector assemblies, this is a significant difference in performance.

scootle,

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Joe
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Based on David's reply, I checked the tightness and made sure the flashlight was not partially unscrewed. I still seeing the "clover" artifact in the beam pattern. Could this be caused by the three "feet" on the end of the lens which prevents it from achieving a flush contact with the LED heatsink?

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jtobrien
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I have the same problem and it's tightly screwed down

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David Hilton
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Clover

First off, the 'clover' artifact is due to the square led.

Irregular Beam Pattern

As to having an irregular beam pattern, I received a second light and definitely noticed irregularities.

I switched carriers, and discovered that the irregular pattern is related to the led board, not the primary lens.

Here's how to fix it.

  • Unscrew the led board (with a PH1 screwdriver), and re-tighten the screws to the point that the board stays in place, but can be adjusted with finger pressure.
  • Adjust the board in the opposite direction as the largest lobe. This is a very fine adjustment, and you'll need to do it multiple times.
  • When you are as centered as you care to be, carefully re-tighten the screws.

Diffusion distance

On my better-calibrated light, the clover is diffuse at about 12 inches, while my worse light is diffuse at 26 inches. I switched carriers, and found that this remained the same between bodies.

This means that the cause is likely a slight difference in led board thickness (the better is .077", and the worse is .074" thick), but it could be changed for the better by any means of bringing the led board and lens closer together.

Edited by: David Hilton ( )

Makes me wonder if some kind of fine-grained "shimming" of the LED board somehow to minimize distance from LED to lens assembly is in order. I wondered if the issue is the spacing from LED to lens (due to how the pattern changes as you unscrew and rescrew the light into the body, and based on your info, that seems to be the case. Thanks so much for taking the effort to bring us this info. :)

scootle,

It's definitely worth looking into, but any solution that alters the led board level will have to address losses in heat transfer. It's probably safer to adjust the lens position.

David Hilton,

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David Marsh
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I was able to improve both of my lights substantially by cranking the carriers hard into the body (mashing the O-ring) and by slightly tightening the retainer rings over the TIR lens (about 1/4 turn), mashing its O-ring as well. I used a block of wood to grip the indents on the retaining ring.

I have to wonder if we are the victims of (practical) tolerance build-up when the lights went into full-production vs. the smaller hand-crafted samples used during design/testing. :( Thanks for taking the time to "mash" those o-rings!

scootle,

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Dan Karg
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I received two lights in the last few days. One of these exhibited this clover effect even at a distance of 15 feet. It was also one that had some amount of fingerprinting/dirt on the back of the lens. By tightening the front bezel down the clover pattern is pretty much gone at 15 feet, and the center spot is nice an bright.

It looks like I'm almost as tight as the one that is good (judging by the amount of threads exposed in front of the bezel ring. I'm unable to make it much tighter, I need a better tool to turn it. I'm glad the good one didn't have finger prints, I doubt I'd be able to get that apart here with out a proper tool.

Can we buy a proper tool for this ?. Maybe another project ?.

Thanks

I too wish the bezel ring was less "proprietary" in design. Fabricating a proper 3-prong tool to work with that is going to prove to be interesting. One thing I hoped with the "open source" design was to not require special tooling to completely and safely disassemble the light, but oh well.

scootle,

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Greg Ammon
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I just added a little silicon grease (nyogel 760G) around the rear o-ring. The carrier tightens down a lot further with very little effort now and the artifact has all but disappeared past 20" or so.

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Mark Huie
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Here's an experiment to try:

Remove the reflector and also the inner core from the housing. You'll notice that there are feet on the reflector to stand it off from the LED some minimum distance.

Hold the reflector in front of the LED and point it at the wall close up with the feet against the LED board. Observe the beam pattern.

Start moving the reflector away from the LED until you observe a similar pattern as your original cloverleaf. What is that distance between the LED and the reflector?

In my case, I had to move the reflector away by a few millimeters. "Hmm..." I say to myself. "That's about the thickness of the O-ring." So I put the reflector in the housing without the O-ring nor the screw-in retaining ring, hold it there with my finger and insert the inner core. I was seeing if the LED carrier/star pushed against the reflector and it didn't really feel like it.

So, it seems to me that the housing can be reassembled with the reflector in first, then the O-ring, then the threaded retaining ring. I tried that and got rid of the clover artifact, however, that adversely affects the water resistance, so I put it back the other way.

I figure that if it really annoys me, I'll mill an aluminum or copper spacer to screw in behind the LED carrier/star to shim it out properly.

So, @David Hilton, yeah, there is some shimming that can be done to bring the reflector closer to the LED, however it's not really fine grained on the order of a few thousandth of an inch, but more like a few millimeters.

If you don't want to go through that much effort, at least you can try to get a thinner O-ring with the same diameter, or cut some gasket material to minimize the distance as much as possible.

PS: Oops, I noticed that the O-ring doesn't really have that great of a seating surface, so I'm not too sure how well a gasket will work while still preventing water intrusion. Since there is a smooth, flat section between the O-ring seat and the retaining ring threads, I might go with a thinner O-ring sandwiched between the threaded ring and the reflector if I could get enough of a bevel on the threaded ring (on the outer, threaded side, not the inside) to force the O-ring against the walls of the housing.

Aw, how am I kidding, I don't really need that great of water resistance. I'm reassembling it with the O-ring on the outside. Now to do a beam comparison with the reflector in each of the two positions...

Edited by: Mark Huie ( )

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Jason
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My lens has fingerprints :( any way to clean?

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James Davis
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I also posted in another thread asking for a spanning bit for the ring. A standard inexpensive two prong bit or retaining ring pliers set would be best - should a two slot ring be used in future production (or a replacement for the three slot ring be found). Most telescope and lens tube manufacturers use dual prong retaining rings and also offer custom bits for their rings.

I'd rather not scar up the unit or take a chance on damaging the TIR lens with less than optimal tools.

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scootle
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Just FYI... here is a proposed fix coming from Christian:

http://www.kickstarter.com/projects/5270...

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