LEDS
Light
Emitting
Diodes
Overview
LEDs are particular type of semiconductor that emits light. Originally they just emitted low levels of red light, they now emit a multitude of colors at a variety of intensities. Due to the advances in technology the past 5 to 10 years, they have become bright enough and cheap enough that they are useful for use in stage lighting.
LEDs have the advantage of being more energy efficient than incandescents lights (ie, it takes less electricity to produce the same amount of light), they produce less heat, and their typical life is much longer.
LEDs are at a disadvantage from incandescent and other sources of light in that they emit only small portions of the EM spectrum. Multiple LEDs must be combined to get white light (often leading to poor color rendering). Newer advances have lead to the creation of a white LED, which is a phosphor treated blue or UV-LED. This is why we often see a CRI rating on fixtures or the newer TM-30-18 rating.
Another disadvantage of many LED fixtures is multiple shadows. Because of the multiple point sources, each LED casts its own shadow. This limited the use of LED fixtures to just wash fixtures for a long time until the the beams was able to combined (or homogenized) into a single beam. This, or using a white LED, has allowed for LEDs to be used in profile fixtures.
Most high quality LED fixtures used in stage lighting use more than just RGB LEDs: many add Amber and White to increase the color rendering of the fixture. ETC fixtures will often use a 7 (Red, Lime, Amber, Green, Cyan, Blue, Indigo) or 8 (Deep Red, Red, Lime, Amber, Green, Cyan, Blue, Indigo) color system.
Another consideration with LEDs is the binning process. It is a process during manufacturing that sorts LEDs by various characteristics, including color, to make sure that the LEDs used by a particular company are as close to the same as possible. The fewer difference, the closer each fixture will be to each other, but the more expensive the LEDs will be.
Learn more about LEDs:
How Light Emitting Diodes Work
The first blue LED
LEDs have the advantage of being more energy efficient than incandescents lights (ie, it takes less electricity to produce the same amount of light), they produce less heat, and their typical life is much longer.
LEDs are at a disadvantage from incandescent and other sources of light in that they emit only small portions of the EM spectrum. Multiple LEDs must be combined to get white light (often leading to poor color rendering). Newer advances have lead to the creation of a white LED, which is a phosphor treated blue or UV-LED. This is why we often see a CRI rating on fixtures or the newer TM-30-18 rating.
Another disadvantage of many LED fixtures is multiple shadows. Because of the multiple point sources, each LED casts its own shadow. This limited the use of LED fixtures to just wash fixtures for a long time until the the beams was able to combined (or homogenized) into a single beam. This, or using a white LED, has allowed for LEDs to be used in profile fixtures.
Most high quality LED fixtures used in stage lighting use more than just RGB LEDs: many add Amber and White to increase the color rendering of the fixture. ETC fixtures will often use a 7 (Red, Lime, Amber, Green, Cyan, Blue, Indigo) or 8 (Deep Red, Red, Lime, Amber, Green, Cyan, Blue, Indigo) color system.
Another consideration with LEDs is the binning process. It is a process during manufacturing that sorts LEDs by various characteristics, including color, to make sure that the LEDs used by a particular company are as close to the same as possible. The fewer difference, the closer each fixture will be to each other, but the more expensive the LEDs will be.
Learn more about LEDs:
How Light Emitting Diodes Work
The first blue LED
Power
LEDs, like other electronics, require DC power. LED fixtures have built in transformers to convert AC power to DC power. This transformer is also typically automatically senses the voltage and can be used with a variety of voltages.
Because of the transformer, LEDs do not function well on dimmed power. They need what is often referred to as constant power. Power that comes from a dimmer, even when at FULL (100%), has its sine wave chopped and can cause problems for LEDs (and other fixtures that need constant power). Newer dimmers can be switched to provide undimmed power, or power can be run from a constant, nondimmed source to the fixture.
At SU, we run power from one of our two power outlets, located up left stage and down right stage. Our dimmers are not capable of being switched to a non-dim mode.
Because of the transformer, LEDs do not function well on dimmed power. They need what is often referred to as constant power. Power that comes from a dimmer, even when at FULL (100%), has its sine wave chopped and can cause problems for LEDs (and other fixtures that need constant power). Newer dimmers can be switched to provide undimmed power, or power can be run from a constant, nondimmed source to the fixture.
At SU, we run power from one of our two power outlets, located up left stage and down right stage. Our dimmers are not capable of being switched to a non-dim mode.
Chauvet B-565FC Fixture
SU currently owns 20 Chauvet B-565FC fixtures, primarily for use as a top and bottom wash for the cyc.
Chauvet B-565FC Overview
Menu buttons - buttons to access the various options available on the LED.
Filter lock - lock can be pulled to allow the filter to be removed. Adjustment handle - these can be loosened to adjust tilt of the fixture. OLED screen - menu can be seen here. Personalities and DMX address can be seen and changed here. Mounting bracket - a c-clamp or other coupler can be attached to connect the fixture to a batten or it can be used as a foot for placing the fixture on the floor. |
Filter slot - filter for the fixture is inserted here.
Filter lock - lock can be pulled to allow the filter to be removed. Amphenol etherCON through - etherCon or other RJ45 connector is plugged in here. 5-pin DMX in - receptacle end of the DMX cable is plugged in here. This provides data to the fixture. 3-pin DMX in - a 3-pin DMX cable can be plugged in here. 3-pin DMX is technically not an acceptable type of connector according to the ANSI standard. Fuse - this fixture uses a T 2A, 250V fuse. Neutrik PowerCON in - power in for the fixture. |
Amphenol etherCON through - etherCon or other RJ45 connector is plugged in here.
5-pin DMX out - plug end of the DMX cable can be plugged in here. This allows for daisy chaining of fixtures. 3-pin DMX out - a 3-pin DMX cable can be plugged in here. 3-pin DMX is technically not an acceptable type of connector according to the ANSI standard. Neutrik PowerCON out - power out for daisy-chaining of fixtures. |