Moving Head Wash Light With Pixel Effects: 10 Questions the K2 FX Answers

Quick answer: The Rasha K2 FX is a moving head wash light with 19 RGBL LEDs and a LumaPix™ pixel layer around them. It zooms from a 5.5° beam to a 55° wash, puts out 58,300 lux at 5 m (16.4 ft) on the narrowest zoom, and has pan and tilt that can keep rotating in either direction. The main light and LumaPix run on their own channels, so one fixture gives you a wash and a separate layer of effects.

Key points

• Zoom: motorized 10:1, from 5.5° to 55°, narrow to wide in 3.1 seconds.

• Output: 58,300 lux at 5 m (16.4 ft), narrow zoom, all emitters at full.

• Effects: 31 macros on the main LEDs and 95 LumaPix effects, which can run at the same time.

• Camera: selectable PWM at 1,200, 2,400, 16,000 or 20,000 Hz, and 16-bit dimming.

• Motion: 540° pan and 239° tilt, plus continuous rotation on both axes.

• Control: DMX, RDM, Art-Net and sACN, in 36, 49 or 125 channel modes.

• Rigging: 42.3 lb (19.2 kg), two quarter-turn omega brackets, hangs in any orientation.

1. Can one moving head do both a beam and a wash?

Yes, if it has a wide enough zoom. The K2 FX has a 10:1 motorized zoom that runs from a 5.5° beam to a 55° wash. At 16.4 ft (5 m), that is a circle about 1.3 ft across at the narrow end, opening to about 14.5 ft at the wide end.

That means one fixture can cut a column of light through haze for one song, then flood the stage in even color for the next, without moving it on the truss. Going from narrow to wide takes 3.1 seconds, which is fast enough to use the zoom itself as an effect on a cue.

2. How bright is the K2 FX, and how far will it reach?

On the narrowest zoom, the K2 FX measures 58,300 lux at 5 m (16.4 ft) with all emitters at full. Peak intensity is 1,457,500 candela. Here is what it delivers at four throw distances, from a production unit, center-beam values:

The full 1 to 20 m tables are in the K2 FX photometric report. Ask the Rasha team for a copy if you are planning throw distances for a specific room.

3. How do you add pixel effects without hanging more fixtures?

Use a fixture that has its own pixel layer. On the K2 FX, that layer is LumaPix. It sits around the 19 main LEDs, behind a diffused cover, so effects read as smooth light instead of dots.

LumaPix runs on its own channels. You can:

• Pick a built-in effect. 95 of them: spins, chases, comets, rings, builds, wipes and rainbows. Each runs forward or backward at the speed you set, with its own strobe.

• Have it follow the main light. LumaPix can copy the main light's color, pattern or output.

• Pixel-map it. A media server can play content across the LumaPix layer over the network.

A background color with its own dimmer sits under every effect. The main LEDs have 31 macros of their own, colored with their own RGBL controls. Run a macro on the main light and a different LumaPix effect around it, or lock both into one look. That is two layers of light from one rig position, without adding a second fixture type.

4. Can a lighting console and a media server control the same fixture?

On the K2 FX, yes, at the same time. Rasha calls this Dual Control. The console always runs the main LEDs, pan, tilt and zoom over DMX. A media server pixel-maps LumaPix over the network. One value on the console hands LumaPix back and forth between the two during the show.

Setup takes three steps:

1. Connect. Console to DMX In. Media server through a network switch to Ethernet In.

2. Set the operation mode. Main: DMX, LumaPix: Network. Set the LumaPix address to 001.

3. Set the LumaPix source. Choose Network Control.

The programmer keeps the position, color and zoom cues they already built. The video team can run content on the pixel layer without asking for console time.

5. RGBL vs RGBW: why use lime in a wash light?

Each of the K2 FX's 19 main LEDs mixes red, green, blue and lime. Lime fills in the greens and yellows that the eye notices most. That helps yellows and warm mixes, and adds output in the part of the spectrum where the eye is most sensitive.

Color is quick to reach from the console:

• Nine preset colors and a rainbow on one channel.

• 22 CCT presets from 2,000K to 10,000K on another, from warm tungsten to cool daylight.

• Calculated color gamut: 100% of Rec. 709, 98% of DCI-P3 and 90% of Rec. 2020.

In the 125-channel mode, every main LED is its own pixel, so content can run across the face of the fixture too.

6. Why do LED wash lights flicker on camera, and how do you stop it?

Most LED fixtures dim by switching the LEDs on and off very fast. This is called PWM. Your eye sees steady light, but a camera can catch the switching as flicker or rolling bands, more so at high frame rates and fast shutter speeds. A livestream or a phone video will show it even when the room looks fine.

The fix is a higher PWM frequency that you can change to suit the camera. The K2 FX lets you choose 1,200, 2,400, 16,000 or 20,000 Hz. At the higher settings the output stays flicker-free on camera. Because every camera and shutter setting is a little different, run a short test recording at your frame rate before the show.

Smooth fades matter on camera too. The K2 FX dims in 16 bits, with four dimmer curves, so slow fades don't step on the way to black.

7. What does infinite pan and tilt mean on a moving head?

It means the head can keep turning past its normal stops instead of reversing. On the K2 FX, regular travel is 540° pan and 239° tilt, both 16-bit. Switch to the Pan Rotation and Tilt Rotation channels and the head keeps turning one way, forward or backward, for as long as you want.

Speed covers a wide range. The fastest full pan turn takes about 1.6 seconds. The slowest takes more than three minutes. Use the fast end to spin beams through the room on a big moment, and the slow end for a drift that the audience barely notices.

8. Which DMX mode should I use: 36, 49 or 125 channels?

Pick the smallest mode that gives you the control you need. Fewer channels means more fixtures per DMX universe:

The K2 FX takes DMX, RDM, Art-Net and sACN. The product page has the DMX charts for each mode. With no console at all, the K2 FX has two auto programs and a sound-active mode.

9. How many moving heads can you run on one 20 A circuit?

It depends on the fixture's maximum draw and your voltage. Plan around the maximum, not the typical draw, and keep each 20 A breaker at 80% load (16 A).

The K2 FX draws 7.0 A at 120 V when operating and 8.4 A at the maximum (780 W operating, 941 W max). At 208 V those numbers drop to 4.0 A and 4.9 A. That works out to:

• 120 V: 1 fixture per 20 A circuit.

• 208 V: 3 fixtures per 20 A circuit.

The input is auto-ranging, 110 to 240 VAC, 50/60 Hz, so the same fixture works on either service. If you are building a larger rig, 208 V cuts the number of circuits you need by about two thirds. These figures are calculated from the data sheet, so check them against your venue's power and local code.

10. How fast can a crew hang, link and address a rig?

A rig only goes up as fast as its slowest fixture. The K2 FX is set up to keep each step short:

• Hang it. Two quarter-turn omega brackets come in the box. It hangs in any orientation, with a safety cable point at the bottom center. At 42.3 lb (19.2 kg), the slim head lines up close to the next unit.

• Link it. Locking power, 5-pin DMX and locking RJ45 network, each with an in and a thru. Power, DMX and network chain from fixture to fixture.

• Address it. Set the address and mode from a phone with the RashaConnect app over NFC, or use the 5-button menu and the full-color display, which flips 180° for hanging units.

• Move it. Pan and tilt locking levers hold the head in place for transport and focus.

A two-fixture road case, RP-K2FX-2-RC, is available separately.

K2 FX specs at a glance

Where does the K2 FX fit?

• Touring and live production. One fixture type covers beams, washes and pixel looks, which keeps the truss and the truck simpler. See concert lighting.

• Worship services. Flicker-free output for the stream, warm whites for the message and effects for the music. See house of worship lighting.

• Large venues and hospitality. A media server can run the pixel layer while the console keeps the main look.

• Events. Wash a room in color, then switch to beams and LumaPix effects when the dance floor opens. See event lighting.

See the K2 FX on your rig

Numbers only tell part of it. Put a unit in front of your programmer and run your own cues.

• Book a demo with the Rasha team

• Find a Rasha reseller near you

• Contact Rasha, or call +1 (951) 654-3585

Full specs, the manual and the DMX charts are on the K2 FX product page.

Related reading

• What to look for in an LED wash light: 10 features that matter

• What is CHROMIND? LED color calibration explained