Lee filters Info and Q & A.

**vortextwist** · 03-13-2007, 08:15 PM

I didn't like the filters. They just seemed to block the light too much. I might not have used the right shades but still turned me off of them.

**xwingband** · 03-13-2007, 08:18 PM

Doesn't work that way... white has are of the frequencies and is filtering out all but those we want. Blue over Red (or vice versa) won't work because there are no common wavelengths in there.

If you were trying to change the tone of a color with a similar one... like toning down the green in a cyan LED it might be okay, but the opposites mixing sucks big time.

**Marsupial** · 03-14-2007, 09:56 AM

d'oh!
it makes sense.

Ryma Mara · 03-14-2007, 10:24 AM

Just an idea here, I dont know nothign about wavelengths and stuff like that.

But what if you pick the colors according to the wavelengths that match the wavelengths of the led?

**LordArgyll** · 03-14-2007, 01:20 PM

That would be a red filter over a red LED, similar to what xwingband just described (cyan is blue + green, a blue filter would decrease the amount of green in the cyan). Other than that subtle tinting, what would be the point? You'd still have a loss of light intensity.

Remember that a Lee filter is literally that... a filter. White light is made up of RGB components. A red Lee filter allows only the Red wavelengths to pass through, blocking the Green and Blue. Therefore, the light you get is only maybe 1/3 as intense since 2/3s of the light is being blocked by the filter.

In the previous example, putting a blue filter over a red LED... a blue filter blocks the green and red wavelengths. Putting a blue filter over a red LED means that it is blocking ALL of the light passing through.

Lee filters don't ADD color to the light... the SUBTRACT from it. The color you see is what is left after that subtraction.

Ryma Mara · 03-14-2007, 03:32 PM

No what I ment was in the swatch book of filters they have a wavelength thing on it. what if you get a filter thats int eh same area of a white leds wavelength.

**neophyl** · 03-14-2007, 04:02 PM

White leds cover a whole range of wavelengths. Thats why they are classified by K (Kelvin, equivalent hue of the white light produced when compared with normal bulb sources, its a lighting industry standard).

Wavelength = colour. All a filter does it let certain wavelengths pass through it while stopping the rest. Theres no point in matching a filter to a non white led except to tweak the shade slightly as was already pointed out.

When you 'see' an object, say red for example. Its red because the substance its surface is made from absorbs all the other wavelengths except the red ones (approx 660nm). A black object absorbs alot more of the spectrum thereby appearing black. Technically theres no such colour as black, its merely the absence of most of the wavelengths of light that we can see.