Moving head 1700 W discharge spot

Robe BMFL, a blank ‘Czech’ for the future of Robe?

This paper is available in Français too

It took three years of Robe’s R&D to develop BMFL and to meet all of its design requirements – a new 1700 W Osram short-arc lamp, a 5-55° zoom range, a new, optimized CMY color mixing system, an electronic stabilizer and only 36 kg on the scale – for an exceptional fixture.
Since early January, the date of its release, 1500 projectors were sold worldwide and production for the next three months is already reserved. It has certainly hit the ground running!


After Aladdin, now Robe has its magic lamp

Starting from the principle that even a moving fixture has to be, above all, a light source, the project is built around a new lamp developed by Osram according to very specific criteria established by Robe. This is a 1700 W short-arc HTI lamp with a color temperature of 6000 K.

Lampe Osram 1700W

The heart of BMFL, the 1700 W lamp specially developed for Robe by Osram

In BMFL, it can be corrected using full- and ½-minus green filters, the CTB filter on the second color wheel and a progressive CTO filter. According to measurements made available to us by Robe, when the lamp is new, with less than 20 hours of use, the CRI (Color Rending Index) reaches 90 (with zoom at 50%), can be raised to 92 with full minus green filter and up to 96 with the ½-minus green.

After 100 hours of lamp usage, the CRI measures 92 in white, 89 with a ½-minus green filter and 78 with a full minus green. One can understand the value of minus green filters to optimize the color rendering based on the number of lamp operating hours.

After a new series of tests, Osram has just confirmed a service life of 750 h, indicating, however, that after this period of use at 1700 W, the lamp loses 40% of its light output and suffers a color temperature drift of about 300-350 K.

The user can select via DMX channel 6 or using the control panel to use the lamp in 1700, 1500 or 1200 W modes. Called “Silent” mode, the latter reduces the noise produced by the fixture by 3 dB and expands its potential use because 1700 W is not always necessary. Indeed, for reasons of security, the clearance (the safe distance between the source and the object to be illuminated) at full power is 8 m. The 1200 W mode reduces the power consumption and helps to integrate the fixture more easily into a lighting rig. The choice of the lamp was also motivated by the desire for maximum uniformity; the short arc option was wiser.

All photons and no picturey !

During the first day of testing, we were able to take advantage of the presence of Ingo Dombrowski, Key Account Manager Europe for Robe. With the help of Kevin Migeon, sales engineer for Robe Lighting France, we set up and connected the fixture.

The tilt lock, recessed into one of the yoke arms for protection

The first detail that makes us very happy is the locking Pan and Tilt, which allow us to move the fixture and get it into its flight case easily.

After a few quick adjustments of the library available at Robe, we unleash the 1700 watts and… how should I say this… it knocks us right on our asses! The light output is impressive – literally and figuratively dazzling. With a tight beam, it’s hard to look at the white canvas that we are using for the measurements.

Ingo tells us that the “Hot Spot” feature, a Robe patent that allows DMX control of the position of the lamp relative to the reflector for a big hot spot or for a wide diffusion of light, has not been implemented in order to ensure uniformity between all BMFLs in terms of beam and color.

Wide beam

Robe BMFL Flux large (EN)

The luminous intensity curve is very smooth despite a small hollow in the center, probably due to a slight downward shift of the hot spot.

We begin with the widest beam, measuring illuminance every ten centimeters on two axes around the center. Our magic table calculates the luminous flux for 10 cm rings and adds them up to give us the total flux. Although the safety distance is 8 meters, we remain at 5 meters from the target for comparison with other fixtures we’ve tested. The first step is already not trivial, 4420 lux at the center of the beam and a total flux of 35,000 lumens!

Faisceau 20°, 36 125 lm, Watt else ?

BMFL Flux 20 (EN)


At a beam angle of 20°, we measure 22,920 lux at the center and obtain 36,130 lumens. The BMFL is the most powerful spot tested to date by SoundLightUp.
The luminous intensity curve has lost its little dip, but not its uniformity. The rapid drop off of the last values is indicative of a sharp edge beam.

Tight beam

BMFL Flux Serre (EN)


With a tight beam, with the iris open, the illuminance at the center is 136,400 lux, for a flux of 34,200 lumens.
The flux remains almost constant throughout the zoom range and is optimum at the middle of the range, which is one of the most commonly used values.

The dimmer

Dimming is electronic on the first part of the range and then the mechanical dimmer takes over. We control the two dimming curves.  The S (Square) curve is perfectly mastered, and we note just one tiny problem at 80% on the Linear curve.

Dimmer square curve

Dimmer Linear curve

Built like a Czech watch

We also take advantage of the presence of Ingo, who followed the whole development of the fixture, to assist us in the disassembly and examination of the various elements that make up the BMFL. No need for a tool box for the disassembly; two Phillips and one slot-head screwdriver, and one pair of pliers  are enough. Once the two covers of the head have been removed, we find the mechanical part of the spot.

Under the cover of BMLF, space is limited to maintain compact dimensions

The cooling system of the head uses no less than seven fans and turbines. The two most impressive, at the bottom of the image behind the grill, are used to bring in fresh air and to remove the heat of the lamp. Each function block has its own smaller fan, and there are small turbines for the most sensitive components such as gobos and the iris. Having multiple cooling sources has allowed Robe to reduce their size and, especially, their speed, which greatly reduces noise.

There is also a very neat wiring, calculated to the millimeter. Ingo points out to us that the motor control boards were located as close as possible to the elements they control. He also tells us that each card has a processor identical to that of a smartphone, to maximize the responsiveness and the performance of BMFL’s parameters. This allows, for example, 24-bit control of the movements of the head via two DMX parameters (ie: 16 bit). The eight additional bits assist in smoothing the movements. The motors are controlled by the processor according to the speed required.

On the back of the head is the plate that provides access to the lamp. It is held in place by three quarters of a turn of the screw. The lamp is then very easily removed by turning it counterclockwise.

The functions are grouped mainly on removable assemblies to facilitate maintenance. The first block comes out by removing two screws. Here’s a little tip: you can loosen some of them until you feel a slight play; that way, you can remove the plates while leaving the screws on their support, to avoid misplacing them or letting them fall if you are working on a fixture mounted up high. There are only two connectors to be removed, the power supply and the signal. The operation requires some attention in a fairly small space, and I recommend using a pair of needle-nose pliers to avoid damaging a connector or pulling out a wire. The plate can then be removed without any problems.

On one side, the two color wheels

On the top there are two color wheels, each with six dichroic glass filters, which can be easily interchanged.

One can also note that the engineering department employed two different drive methods: some functions are driven directly by the motor shaft while others are actuated via a toothed belt.

Both of these systems have been proven for a long time and allow precise recalibration.

On the filp-side, the shutter. You can see the pattern etched on the CMY color mixing filters

On the bottom – the lamp side – is the shutter. Below, we find the progressive CMY and CTO filters, major innovations incorporated into the BMFL, which are the subject of a new patent registered by the Czech manufacturer.

Building on the base used for many years, two glass plates that close, Robe has developed a laser-etched pattern that allows optimum color mixing and perfect uniformity over the entire beam from 0 to 100%.

The two gobo wheels and the surprising effect wheel system

The gobo block requires a little more effort, because you must remove one of the two large fans to release it. Here we find, on one side, the two gobo wheels and the module with the two effects wheels.

On the other side there is the iris, with a system that allows very quick off-axis drive. There are also the motors for all the features and two supplementary turbines. We can see that all the electronic boards are equipped with connectors for quick and easy maintenance.

The two dimmer blades are completely undetectable in the beam.

When the effects and color blocks are removed, we find the two serrated dimmer blades with two strips of frost.

By contrast, towards the top of the head, on the output end, are the two 6-facet prisms (one linear, the other radial), the two frost filters and, finally, the focus and zoom.

The two covers of the yoke arms are held in by six screws.

The tilt drive and locking tilt

The pan and tilt board and the pan motor

The arm that houses the tilt lock contains the drive system of the tilt via the belt, its tensioner and the large toothed wheel that drive the head.

On the other side is the impressive hybrid triphase stepper motor for the pan and the pan and tilt control board.

Two optional handles are screwed to the back of the head to use BMFL as a follow spot…

… with an associated menu

The base

The projector base, which houses the power supply and the motherboard, is cooled by two fans. On the side opposite the display, connectivity includes two XLR5 (male and female) and two XLR3 connectors for DMX control, and a Neutrik EtherCON RJ45 connector for controlling the fixture via ArtNet, sACN and MA-Net 1&2.

The connections on one side of the base

. Also, you can change certain parameters or receive various information from the fixture through the RDM protocol. Power is supplied through a PowerCON-A connector. It is protected by a 12 A fuse, just above the connector.
Robe offers to incorporate a Lumen Radio CRMX receiver board as an option, allowing DMX control over WiFi.

During the disassembly, we found that the mechanisms are very neat and perfectly adapted.

All ahead full speed !

The dimmer was a challenge facing the Robe team and they come away with honors. The beam remains uniform from 0 to 100% regardless of the transition time and the change is even noticeable over the last three percent, where there is often an abrupt opening or closing. At no time did we see the blades interfere with the projection. The strobe function is also mechanical and electronic. It reaches a frequency of 10 Hz. As we said a little earlier, there is 24 bit control of both pan and tilt axes. The result is very smooth movement even with significant transition times and complicated movements. To be able to notice any defects, it was necessary to take it up to a 40-second traverse of a 7 meter, 45° diagonal

With fade times of 0, the movements of the head are impressive in terms of speed and accuracy, with sharp stops and with no slowing. It takes 1.56 s to pan 180° and the same time to tilt 180°. In the video we can see that, during reset, the dimmer switches off when the pan and tilt reset starts. It would have been better to have a little fade, followed by the reset.
Unfortunately, we were not able to test the innovation brought to the movements by the EMS (Electronic Motion Stabilizer) system, which absorbs vibrations due to sound, movement of trusses or to the fixture being placed on a surface that is unstable or sensitive to sound waves.

One of the priorities in the specifications of the BMFL regards color and, especially, color mixing. The fixture includes two color wheels: one dedicated to saturated hues that perfectly complement the CMY color system, and the other with pastels, including three light hues and three color correctors – a CTB at 8000 K and two minus-green filters (½ and full). The CTO is also progressive, variable from 2700 K to 6000 K.

BMFL colors

As we saw during disassembly, Robe has developed a new system of lines etched on the dichroic filters that allow the fixture to produce a wider range of colors that are more uniform. The quality and consistency of the colors are impressive. Regardless of the zoom setting or focus, at no time do we see anything but a blade of color back down the beam. We obtain sublime pastels, perfectly distributed over the entire beam. The saturated colors also stand out, both in brightness and in possibilities. However, it lacks a deep green and the red that it generates at maximum is a saturated orange.
Having to choose between pastels and saturated colors is a dilemma that comes up in virtually all fixtures. The solution for LED sources is to add components to the red, green and blue primaries in order to supplement the color palette. This is perhaps one of the avenues to take for discharge lamps by giving the choice of two shades of yellow and two shades of magenta.

To complete the chapter of colors, hats off to the development team for the velocity of the CMY mixing system. I had never seen such rapid transitions from DC motors… even faster than the color wheel !

A sampling of colors using the CMY system




the pastel color wheel

The saturated color wheel

This new spot has two wheels with six rotating gobos each. The selection makes sense and is artfully arranged. The first wheel is dedicated to projections for highlighting set pieces or dressing up spaces.

A good selection of gobos for projections, enhanced by very good optics.

The second wheel is equipped with aerial effect gobos. The choice of gobos is always complicated, but the selection included should satisfy many users.

The aerial effect gobos

To animate the gobos, you can also use – or combine them with – the animation wheels. There is, in fact, a system of two rotating and indexable wheels for creating magical effects. For the impatient, there are presets that combine the effects of gobos and effect wheels. It is also possible to combine gobos and effect wheels with one of two prisms, linear or circular, each with six facets.
The BMFL features two frost filters: one “Light” which, among other things, allows you to “smudge” gobos, and a second “Medium” filter. The combination of these two filters makes it possible to create a third, “Heavy”, frost.

The effect of the linear prism

The effect of the circular prism

Everything about the optics was also a key point in the development. The range of aperture with sharp beam edges covers almost the entire zoom range and, even with the iris, we remain focused until almost the end of the range. The icing on the cake is the amazing speed with which these parameters can easily create dynamic effects. Only the focus drags a bit, creating a slight slowdown if you create a “cut” with the small, sharp iris at a wide, sharp  zoom setting.

The powerful and uniform beam

Even wide open, there is power and clarity

A big step for Robe

With Pointe, the Czech brand had opened up the door, but with the BMFL it has both feet in the big leagues! This new spot has no shortage of features to attract a large number of lighting designers and cinematographers

In the Impact Evénement parking lot, the BMFL goes the distance

What more can I say?

in addition to being efficient, the BMFL is extremely versatile and able to adapt to all situations. The design is very well thought out and, apart from two points – being very picky – there is nothing wrong. The optical quality is excellent, all functions have been carefully designed and implemented

It is as much a fixture for effects as for illumination. It is equally as good with dynamics as with finesse. This versatility makes it suited to all applications, be it television, events, ballet, theater or concerts.

Not having tested all the existing fixtures, we can not tell you whether it is the best or the most powerful, but it is certainly in the top lines of the chart. We can already tell you, however, that the Wash/Beam and profiling versions will be presented in April at the ProLight+Sound.

What more could Robe Lighting France have asked for a better grand opening ?

BMFL General-1BMFL General-2









Crédits -

Stephane Mocret

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