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Homemade LED lens angles

By jpack - Posted on 11 January 2009

NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.

What sort of angle lenses should i use with my homemade LED lights. There are 7, 10, 25 and 45 degree available.

i want a spot (7 or 10 deg)
and a flood?


Do you have more details? Like:

- Head or bar mount?
- Number and type of emitters?

FWIW think I went with 8-6-16-8 degree on 4 emitters. You defo don't want to go over that 16, it's really quiet wide. I'd go the 10 or 7 + 10 or mixture thereof. Stay away from 25 + 45 basically.

The lights are a dual lamp handlebar setup.
2x Cree XR-E LEDs

specifically make and model number? This is important information to have before you decide which degree to get and the reason is simple. Some manufacturers quote their beam angles as half angles and some as full angles. What that means is a 7 degree from manufacturer might be as much as 14 degrees in reality. You also need to appreciate that seven degrees, for example, will be the edge of the beam. By that I mean there will be considerable "spill" evident. To meet certain standards the lense needs to have a certain percentage of light in that area.

Another thing to consider is whether the lenses are "smooth" or "frosted". A smooth lense will have better "throw" than a "frosted" lense of the same angle but may show more artifacts in the beam.

Also, as Rob has asked, are these for bar lights or helmet lights?

Let there be light

The lenses i have at the moment are a from Jaycar
the 10 deg
and the 25 deg

they are handlebar mounted.

the next set i make will be for the helmet

They are only 5 bucks anyway

for the bars. My take is that bar lights are used to light the trail immediately in front of the front wheel out to between 10 and 20 meters. The helmet light should be the tighter beam pattern to punch the light further down the trail and also to allow you to see "around the corner" through the trees, a flood won't do this.

If you have multiple emmiters on the bar then maybe a flood pointed down and a medium or even tight lense aimed up slightly to give you that bit more distance.

This does tend to be personal choice so if you already have the lenses as you said above, why not try them both and see which one you feel happiest with?

Let there be light

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