This is a special multi-part team post from Katie G. and Andy.
This blog is coming to you as a collaborative effort as we both took on the task of doing major research on the newest forms of LED instruments. LED fixtures unlike traditional tungsten fixtures utilize multi source point compared to a single source point reflector combination of the old system. These multi source point fixtures are composed of a series colored light emitting diodes arranged in groups. Each of the diodes in these groups are single color beams that mix together to create a single smooth field beam. Each generation of LED fixtures has groups of colored diodes consisting of three, four, or seven. LED fixtures containing three colored diodes per group use red, green, and blue color mixing; this type of mixing does not take into account for the orange, yellow, indigo, and violet wavelengths. Eliminating these wavelengths causes the field beam to either too warm or too cool, resulting in an imperfect white field. The LED fixtures that contain four colored diodes in each group help to eliminate this problem by adding a fourth diode colored amber. The amber diode begins to account for the missing wavelengths of the three diode fixture, thus creating a closer to perfect white. Most seem to think that by increasing to seven diodes you would create the perfect white; in theory this concept would hold true, however the current technology of the seven color diode fixtures fails to meet this expectation. Failure results due to the additional three diodes wavelengths result in less luminous cells within the beam field, these dead zones decrease the maximum saturation of field color. The distance between diodes and number of colored diodes within each group seems to be most efficient within a four diode LED fixture.
The transition into replacing traditional theatrical lighting fixtures with new LED lighting fixtures forces us to deal with the relationship between source and reflector. The most successful LED cyc fixture we have experienced so far is the 100w spectra-cyc LED fixture by Altman. We believe their success has arisen in maintaining the traditional J-reflector in previous cyc fixtures. This has allowed them duplicate the successful field properties found in traditional cyc fixtures. Competitor products that do not maintain the traditional relationship between source and reflector including the newly acquired Selador line of LEDs by ETC cannot duplicate the field results of the asymmetrical color mixing.
Please check back tomorrow for Part II as we explore the LED PAR and spot fixture from around the trade show.