Join Date: Jun 2007
Location: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
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Originally Posted by Unknown Cyclist
I've tried P7s and R2s with a few different red filters and the Ultrafire is much brighter.
There's no point it turning your front light into a rear, you don't get much light and you just have to buy another front light.....
It's worth noting that the energy of a photon is proportional to it's frequency (violet can have nearly twice the energy of red), so if you filter out everything but red you are losing more than 80% of the light and only keeping the lower energy part.
The redder the filter the more light it's stopping, so realistically you may only be allowing less than 10% of the light emitted by the P7 through.
Still......if it's a cold night you can warm your hands on it.....
this, and white LEDs are not white to begin with.
most use a blue LED with phosphor coatings to produce red and green which results in a visibly white light.
the higher power violet and blue lights aren't as visible from further away due to the wave length.
green, amber and yellow are quite good for being seen.