UCL in a SureFire L4?

[Ginseng]

Hi, just wondering if anyone has replaced the Pyrex lens in their L4 with a high transmission unit. By my measurements, the L4 lens is 22.4 x 2.7 mm. So, a hair smaller and 0.8mm thicker than the smallest aftermarket unit from Flashlightlens.com.

I am motivated to ask this because I recently had the front bezel off and compared the output with and without the lens and the effect was dramatic even in common room lighting. This little lens is sucking up a large amount of light.

It might be able to squeeze in a 22.6mm unit from FLL but then a second flat O-ring would be required to maintain water tightness.

Any ideas?

Wilkey

 

[Mr HG]

How about putting two lenses together to replace the stock one?

 

[nexro]

I think the tiny gap between the two lenses will cause some light to be reflected backwards. Also, two lenses will be too thick.

 

[kongfuchicken]

Wilkey, your best bet is to ask Chris at flashlightlens.com directly. He's done custom cut UCLs for the same price and I'm sure he'll help you with your problem. If he doesn't have a SF L4, you might need to send him the measurements of the pyrex lens as well.
The real tricky part might be to remove the lens in the first place and as you mentionned, ensure the seal is still good...

 

[Ginseng]

KFC,

Chris is out of the business of making custom lenses right now. Although, maybe if there is enough interest in a lens build for the KL4, perhaps he'll consider it. Right now, I am investigating other avenues. None of them look to be as inexpensive as FLL can do it.

Perhaps this is a red herring.

Wilkey

 

[Disciple]

Ginseng, have you made progress procuring an UCL for the KL4? I have an L2 that I would like to outfit with an UCL, and I think it uses the same size as the KL4.

 

[Ginseng]

No luck. The manufacturers of "windows" for scientific purposes want $80-$100 a piece! Yep. You heard that right.

Unless Flashlightlens.com decides to enter this market, there are no options. But, I don't think that makes a difference after all and I'll tell you why. When I had the lens out, I found that the inside was in fact AR coated. That's the only side that counts. In fact, the UCLs that FLL sell only need to be coated one side as well.

I've been working on something special with a thin lens from FLL and a little something else special. I should be able to post in the near future.

Wilkey

 

[Disciple]

Thanks Wilkey. Something is confusing me, however. You said: "This little lens is sucking up a large amount of light." An UCL should pass over 99% of the light, right? So wouldn't the UCL be an improvement over the KL4 lens?

 

[Ginseng]

Well, that's true. But the stock lens is almost 2.8mm thick while the UCL is closer to 1.9mm. And I don't know what grade of glass is used in the L4 lens. It may not be as high transmission as the glass in a UCL. Also, having a coating on the front as well (like the UCLs) would reduce back-reflection and in that way, increase transmission just a bit more.

I've been field testing a 1mm UCL in my L4 and it's looking really good to me. I hope to do a lux measurement in the near future.

Wilkey

 

[wquiles]

If you can, post a picture of the finished "product" - maybe also a beam shot?

Will

 

[xpitxbullx]

Is that the same Snowblower L4 you are modding with the UCL?

Jeff

 

[Ginseng]

Yup,

Ol' Faithful is getting an upgrade. /ubbthreads/images/graemlins/grin.gif

Wilkey

 

[Ginseng]

Wilkey

 

[KevinL]

Is that what happened after the upgrade? That's sweet.... the light looks as good turned OFF as it does turned on!

 

[Ginseng]

I took some comparative measurements. With the 1mm UCL in place, the lux reading was about 4-5% higher than with the 2.77mm stock lens. This was measureable but not visible, at least not to my eyes. Going to no lens bumped it up to 5-6% over stock. I think this means that a thinner lens with AR coating on both sides does let more light through...but it doesn't necessarily mean you'll be able to see the effect.

The additional benefit of going to the thin lens is that I was able to sand down a glow ring to fit between the front gasket and the lens. The rear, rubber gasket is still in place between the lens and reflector. It's pretty nifty I think and adds just a bit more functionality to an already great light to set it apart from its totally stock comrades.

Wilkey

 

[wquiles]

Wilkey,

The light with your mods DOES look better than the "stock" units - I love the Glow in the dark look /ubbthreads/images/graemlins/grin.gif

Will

 

[chrisse242]

I never saw this kind of glowring before, where do you get them? Could be a nice addition to many lights...

Chrisse

 

[Reptilezs]

[ QUOTE ]
chrisse242 said:
I never saw this kind of glowring before, where do you get them? Could be a nice addition to many lights...

Chrisse

[/ QUOTE ]

looks like glow in the dark paint to me. i dont now where to purchase it off hand

 

[Ginseng]

Hi Chrisse,

It was originally a glow ring for an Aleph2 head. I sanded down the thickness so that stacking it on top of the 1mm UCL, the total spacing would be exactly the same thickness as the stock lens. This means the new thin lens is set in farther from the front of the light. I also sanded down the outer perimeter of the ring (where the threads used to be) so it would drop in and be securely seated in the front of the head. And then I just sanded the rest of the radii and surfaces butter-smooth. Overall tolerances are +/- 0.02mm.

So far, it's been very secure

Wilkey