On film and TV sets, moving lights can give you more control once a fixture is rigged than traditional static film lights. If a source is high on a roof, outside a window or positioned a long way from the action, being able to adjust its position, beam, focus, frost or colour from the desk can save time and avoid unnecessary access. 

But that only helps if the fixture also performs exactly as you expect it to on camera and on set. When I’m talking to gaffers, DoPs, and rental teams about Robe moving lights, a lot of the questions come back to the same core areas: output and throw, low-end dimming, colour fidelity, beam shaping, how the fixture can be rigged and positioned, and how it performs outdoors in changing conditions. 

Here are my answers to ten of the questions I get asked most often, to give you a head’s up when specifying for your next shoot. I’m always happy to answer your questions directly though, so if you do need any help, drop me an email: Andrew.woodfin@Robeuk.com.   

1. When would I use the High Performance (HP) engine and when would I use High Colour Fidelity (HCF)? 

I get asked this a lot, and the answer depends on what the fixture is doing in the shot. 

If you need to light a building, landscape or another part of the background from a long way off, output may be the priority. If two people are talking in the foreground and you need a castle in the distance to register in a night exterior, the HP engine gives you more level to work with. 

Closer to camera, colour fidelity may become more important. If the source is lighting faces, costume or production design, you want those colours to reproduce accurately. That is where the HCF engine comes in. 

The useful thing about fixtures such as the iForte and iForte LTX is Robe’s Transferable Engine system. You can change between HP and HCF in around five minutes without changing the whole fixture. 

It’s important to note that the HCF does still give you a high-output source, but there is some loss of output compared with HP. The transferable engine turns that into a five-minute engine change rather than a full, long-winded fixture change to the rig. 

2. How smoothly does the iForte LTX dim at very low levels? 

The iForte LTX uses 18-bit internal dimming to give much finer control as the output approaches zero. 

That is important because a high-output fixture may still spend much of a scene at low intensity. The bottom of the dimming curve is where stepping or an abrupt drop in level is most noticeable. The 18-bit processing gives finer resolution through that range, helping the fixture fade smoothly into blackout or hold at very low output. 

When lighting for camera, flicker is an important part of the same conversation. Robe’s Cpulse system lets you adjust the LED pulse frequency to suit different camera settings, including higher frame rates and different shutter settings. 

3. How much throw do you actually get from an iForte LTX? 

The iForte LTX is designed to maintain useful intensity over long distances, which is why it can work well on large sets and exterior locations. 

The key question isn’t just how many lumens leave the fixture, but how much illumination you still have when the beam reaches the subject. 

The fixture may need to sit outside a wide frame, across a courtyard, on a roof or well back from a building. At those distances, output and beam control have to work together. Keeping the beam narrow concentrates more of the available output onto the target, so you still have a usable level at distance. 

The best approach is to work from the throw distance, beam size and required level at the subject, then check the photometrics or test the fixture at the working distance. 

4. How tight can you get the beam on an iForte LTX? 

The iForte LTX can produce a very tight beam, including a dedicated long-throw range below one degree. 

That’s useful when you need to keep the beam concentrated over a significant distance, whether you’re picking out part of a building, putting a hard shaft through an opening or running a defined beam through atmosphere. Even a small change in beam angle makes a big difference by the time it lands. 

A very tight beam gives you a hard, concentrated source, which you can then modify with focus, frost, gobos or framing to suit your shot. 

5. Can I use custom gobos in an iForte LTX? 

Yes. The iForte LTX has five rotating and indexable glass gobo positions, and the standard gobos can be replaced with custom patterns. 

That’s really useful when you need a particular breakup, architectural shape or production-specific pattern. You can resize the gobo with zoom, adjust the focus, rotate or index it and combine it with animation. The framing shutters can then keep the pattern within the area you want to light. That keeps the effect adjustable from the desk, even if the fixture is difficult to access. 

Custom gobos need to meet the correct size, material and heat requirements, so it is worth checking the specification before having one made. 

6. What frost options are available on the iForte LTX? 

The iForte LTX uses Robe’s MagFrost system, with several different frost grades available depending on how much diffusion you want. 

A light frost can take some of the hardness out of the beam while keeping most of its direction and intensity. Heavier frost spreads the beam further and gives you a softer source. That’s useful when the fixture is somewhere awkward to reach or when you need the same source to change character between setups. 

As you add more diffusion, the output is spread over a wider area, so the choice is always a balance between softness and the level you need at the subject. 

7. Can I put an iForte LTX on a Long John? 

Yes. An Forte LTX can be mounted on an appropriate heavy-duty stand such as a Long John using the correct bracket arrangement. 

That makes it easier to use the fixture as part of a floor package rather than only in an overhead rig. The iForte LTX is a substantial fixture, so the stand, bracket, load, ballast and working height all need to be appropriate to the setup. 

Once it is safely positioned, pan, tilt, zoom, focus, framing, colour, iris, frost and gobos can all be adjusted from control without physically moving the fixture.

8. How useful are gobos for foliage and natural breakup? 

Gobos can work very well for foliage, tree shadows and natural breakup, particularly when the source needs to remain adjustable from the desk. 

I have spoken to a lot of gaffers using gobos for exactly those kinds of effects, and they’ve had great results. With the iForte LTX, you can change the scale of the breakup, rotate it, alter the focus and soften it with frost. Animation can add movement, while the framing shutters keep the effect off areas where you do not want it. 

There are still plenty of shots where real branches, a cucoloris (‘cookie’) or another conventional solution will be the better choice. A moving light becomes particularly useful when the fixture is difficult to reach or the effect needs repeated adjustment between setups. 

9. What does IP65 mean when using a Robe moving light on location? 

IP65 means the iForte LTX is designed for outdoor use, while Robe’s RAINS system also manages moisture inside the fixture. 

That matters because an outdoor head is repeatedly heating up during operation and cooling down again in damp or changing conditions. Condensation inside the fixture is a different problem from rain physically entering through the enclosure. 

RAINS manages that internal moisture, and the built-in pressure test lets a rental team check the enclosure after maintenance. For a crew on location, the practical benefit is that the fixture is designed to remain rigged outdoors without needing improvised weather protection every time conditions change. 

Normal outdoor working practices around power, cabling and rigging still apply, but the fixture itself is designed for outdoor use. 

10. How does an iForte LTX cope with extreme cold? 

The iForte LTX uses Robe’s POLAR+ system to keep the fixture ready for use in very low temperatures. 

If the fixture has been left rigged outside or sitting in freezing conditions, POLAR+ maintains the required internal conditions while it is in standby rather than letting everything drop to ambient temperature. That means the fixture is ready when the crew needs it, rather than requiring a lengthy warm-up first. 

For most productions, those extreme limits will never come into play. But on a genuinely cold location, it is useful to know the fixture has been designed for that situation. 

Got a question about using Robe on set? 

If you’re preparing for a shoot and have a setup in mind, tell me where the fixture needs to be positioned, what you need it to light and what you want or need to be able to change once it’s rigged. That usually tells me pretty quickly whether a fixture is the right tool for your shoot. 

If you are considering a Robe moving light for a production and want to test a particular throw, look at colour on your camera or try an effect before you commit to it, get in touch. I can give you a demonstration, talk you through any issues you have on set, and answer your questions.