NOOOO! Scratched lens on on C2 ... aarrghh...

Since I wanted to clean the inside of the lens, I heated up the bezel from my C2 and unscrewed the lens retaining ring via one of those 4-way screwdriver thingies that happen to fit the notches. Wouldn't ya know it? It slipped and put couple of ugly scratches in the lens. NOOOO! One thing I noticed is that the stock lense is THICK! Man where would I get one of those? I put a UCL from flashlightlens in there (took it out of my G2) and I'm back in business. But I noticed something odd. The UCL seemed to make my light brighter than the stock Pyrex lens. Is it because of the thickness? Maybe I'm seeing things but it sure seems like it. If thats the case then everylight I get is going to get a UCL in it! Another thing I noticed is since the UCL is thinner than the stock lens, the retaining ring screws down further which means I can take the flat rubber o-ring out of a spare G2 bezel I have and sandwich the UCL between two of them for added shock protection. Neat, huh?

The UCL seemed to make my light brighter than the stock Pyrex lens. Is it because of the thickness? Maybe I'm seeing things but it sure seems like it. If thats the case then everylight I get is going to get a UCL in it! Another thing I noticed is since the UCL is thinner than the stock lens, the retaining ring screws down further which means I can take the flat rubber o-ring out of a spare G2 bezel I have and sandwich the UCL between two of them for added shock protection. Neat, huh?

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The thickness isn't really much of an issue. The biggest loss is from reflection -- if you shine a light throught a standard household window, observe how a significant amount of it is refleced backward. This happens in flashlights without anti-reflective-coated lenses -- a lot of the light gets bounced back into the light, or ultimately scattered so that it won't be as usable as light that is collimated with the main beam. Scratches to lenses make thinsg worse as well, which is why plastic lenses are quite bad for transmission as the tend to get very scratched.

The fact that the lens has an anti-reflective coating is more important than the thickness -- if you were to use a thicker UCL lens, the difference in transmission would still be fairly minimal -- most of the light is lost in the transition from the outside air into the lens, then out of the lens later, rather than the thickness of the lens. This is why fiber-optic cables can be effective even with extremely long length. Considering that the C2 is so cheap to begin with, another $4-$5 invested in a UCL makes great sense, as total cost still isn't all that much and you end up with a better light.

C2 cheap? You must be rich.

DrifT3R said:

C2 cheap? You must be rich.

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I thought we were talkikng about the $22 C2 knockoff, since we were talking about transmission improving with a UCL, not the actual Surefire. I woudl have expected the surfire to come with a UCL to begin with, my mistake

Although in that case, even if it was a UCL to begin with, I suspect that the fact that the new one had no scratches/scuff marks etc. on it probaly improved the transmission a bit.