Light Filterphotography

If the colors are used for architectural features, then the color shift at the edges may not be acceptable. Always test filters if you are unsure about the effects!

Colour filters Physics

The other way to change colors is to use tinted glass filters – these are less costly than dichroic filters but they absorb more light (are less efficient) and tend to fade with time.

Lightfilters for LED lights

GelLight Filter

This is an important question. Every color filter (regardless of type) reduces the quantity of light that passes through. There is no way to transform the entirety of a beam of white light into a beam of (for example) green light. A green dichroic filter works by reflecting (back into the fixture) all the non-green wavelengths of light and only allowing the green portion to pass through. If the initial proportion of green light was only 5% of the white spectrum then the resulting quantity of green light will only be 5% of the original. This is why the purer (saturated) the color, the greater reduction in perceived brightness. The resulting illumination will be beautiful, but may be less bright than anticipated and require a light source with higher lumen output.

LEDLight Filtercovers

Some of the more saturated color dichroics show color shifts at the edge of the beam – all dichroics have this issue because the incident angle of the light source(s) determines the projected color.

The color shift can be minimized through use of an additional diffusion filter placed on top of the dichroic filter. We suggest trying the VOLT®’s Wide Spread Flood Filters (with Micro Lens Technology). Note that the use of this filter will reduce lumen output to a certain extent.

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Brightness is also dependent on what is being illuminated. Lighting a tree with dark-colored bark requires a much brighter light than lighting a light-colored object. The most saturated of the filters (such as red, green, and indigo) should only be used on light-colored objects.

For example, white light contains all colors in the visible light spectrum. If you pass that light through a blue dichroic filter, only the blue portion of the white light passes through while all the other colors are reflected back towards the light source.

Wider angle optics exhibit more color shift than do narrower optics since incident angles exiting the filter are wider. Having said this, the color shift (at the beam edges) in most cases is acceptable and may even be desirable since these saturated filters are mostly used to achieve dramatic effects.

It is highly recommended that designers test color filters on specific applications before they commit to purchasing the filters for a project – and to use fixtures with high lumen outputs.

Dichroic filters are circles of glass with a set of coatings that reflect certain colors (of light) and allow other colors to pass through.