A couple questions please

Can someone explain lumens to me? Are the lumen rating on lights at the emitter or lamp? What effect does the reflector and lens have on the output, do they decrease the lumens out the front? I'm just trying to get a handle on the terminology. Secondly I have a JB MKII w/123 tube do you think it would be alright to put heat shrink tubing on the head I want to protect the lite from scratches while in my pocket. Thanks for any help. George

trapn1 said:

Can someone explain lumens to me? Are the lumen rating on lights at the emitter or lamp? What effect does the reflector and lens have on the output, do they decrease the lumens out the front? I'm just trying to get a handle on the terminology.

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The reflector and lens basically absorb some light and turn it into heat so yes, they do reduce the light being emitted. I hear numbers approximating a 30% loss from the emitter to the actual beam. More detail is in the welcome mat post - read all this stuff and you'll be an expert!

https://www.candlepowerforums.com/threads/172991

trapn1 said:

Secondly I have a JB MKII w/123 tube do you think it would be alright to put heat shrink tubing on the head I want to protect the lite from scratches while in my pocket. Thanks for any help. George

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Well, the heat shrink will reduce the ability of the head to transfer heat to the air so if the light runs warm without it, it may be an issue. But probably its OK since the head is connected to the body reasonably well so there is still a heat path.

Scratches are the mark of a good flashlight. Dresser queens sit there and look pretty. Real users go out and get grungy!