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Thread: Light loss in MR16 cover glasses

  1. #1
    Join Date
    Aug 2011

    Default Light loss in MR16 cover glasses

    I've been slowly replacing my MR16 50 watt pot lights with LED - my local supplier no longer even stocks the GE bulbs I was using, and I'm not happy with their current substitute. I've found some Sylvania MR16 LEDs at Lowes, which claim 700 lumens on the box - the FNV halogens I was using were claiming 800 lumens. I think the light level is equal or better.

    I think it helps that the LEDs don't need the protective lens that the halogens needed. Thinks I to myself "Just how much light could a little glass cookie eat, anyway?" So I stacked up 9 of the protection lenses off my MR16 pot lights and measured how much light got through them- it was 1267 lux before and after the stack, and only 522 with all 9 on the light meter. Take the 9th root of 522/1267 and each lens passes only .906 of the light going through it.

    I then washed all the lenses and got 615 out of 1230 lumens to pass through the stack - so each one passes .926 of the light, much better. But who's got the time to wash lenses more than every second year?

    So, my 800 lumen halogen bulbs were wasting 72 lumens each. The LEDs don't need the cover glass, so I get parity between LEDs and halogens.

    I find this kind of measurement very interesting - I'm getting good value out of the light meter I picked up at Princess Auto.


    Last edited by Kitchen Panda; 04-29-2019 at 07:16 PM. Reason: typos

  2. #2

    Default Re: Light loss in MR16 cover glasses

    I had thought you lost around 2% every time light went in or out of a piece of glass. You're getting around 5% loss?

    /Stops to look at the sight of a panda, equipped with tools, going through the kitchen flashlight drawer/ Decides the meds must be just about right now/
    Last edited by Ken_McE; 11-23-2019 at 08:57 AM.

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