I have been on a quest for the right constant light for a while now. The black and white paper reversal work I have been doing has an effective ISO of around 0.6 to 0.9, which is brutally low and demands a serious amount of light to make portraits possible at usable shutter speeds. I have tested several lights on the channel recently and most have been good for general work but not quite enough for paper reversal.
The Sirui C150X Lite might be the one.
Quick admission before we start. The brand is called Sirui, pronounced “sirai” (S-I-R-U-I, but pronounced with the U silent or roughly so). I have been calling it sirui throughout my reviews of their tripods and have apparently been wrong all along. We have all learned something here.
What it is and what comes in the box
The Sirui C150X Lite is a 150-watt COB-style constant light aimed at the semi-professional end of the market. Slightly more serious than the affordable handheld LED panels I have tested before, but well below true studio-pro pricing.
The kit Sirui sent includes:
- The C150X Lite head itself. No internal battery. Powered externally via the included pack, a D-Tap cable from a V-Lock battery, or USB-C.
- A battery-handle power pack. Heavy, chunky, holds the cells. Connects to the light via a D-Tap cable.
- An adapter to connect the battery handle directly to the back of the light.
- A standard reflector. Clips into the front via a miniature Bowens mount.
- A D-Tap cable for connecting battery to light.
- The QR40 octobox softbox, with two layers of attachment material: a diffuser (front-mounted via velcro) and a grid.
The grid is the bit I was most excited about. Soft boxes with grids let you keep the softness of the light while still controlling the spread, which is the kind of thing you usually only get on more expensive modifiers. Having it included in the kit is a real value-add.
![PLACEHOLDER: the Sirui C150X Lite assembled with the QR40 softbox and grid, on a light stand]
Power options and the D-Tap angle
This is a multi-power-source light. The primary input is D-Tap, which is the standard professional video power connector and gives you compatibility with V-Lock batteries (the chunky pro batteries used on cinema rigs). USB-C is the secondary input. The supplied battery handle adapts to the same D-Tap socket.
For my own use that means I can:
- Run the light off the included battery handle for portable work
- Run it off a V-Lock battery if I have one available (I do, because of the TV work I do alongside the photography)
- Run it off USB-C from a power bank in a pinch
That kind of flexibility matters when you are working in different environments. The TV side of my work has V-Locks already and being able to use those to power photography lights is a small but genuine convenience.
The handle itself is heavy. The whole assembly with handle plus light plus modifier is theoretically handheld but you would not actually want to handhold it for long. My arm gave up within about two minutes of trying to do my piece-to-camera with the light in my hand. The kit is designed for portable use on a stand, not for genuinely handheld shooting.
Mount type and modifier compatibility
The C150X Lite uses a miniature Bowens mount, not a full-size Bowens. The QR40 softbox in the kit fits this miniature mount directly.
Sirui sell a separate adapter that converts the miniature mount to a standard Bowens mount. If you have existing Bowens modifiers (which I do, lots of them, from the Bowens Esprit kit I have been building up), the adapter is essential. I will be picking one up when I get back to the UK.
For the in-the-box experience, the QR40 is genuinely excellent. The grid is the real value. The diffusion is even and clean. The overall light quality is the kind you would expect from a much more expensive setup.
![PLACEHOLDER: the QR40 softbox with the grid attached, showing the light pattern it produces]
Power output, in real terms
This is where the C150X Lite earns its keep. The output is properly impressive.
To give you a sense: with no modifier on the light, at full power, pointed at my camera from about a metre away, I had to crank my shutter speed to 1/4000th of a second to avoid overexposure. At 1/1000th of a second, the camera was still overexposed. This is a lot of light coming out of a small package.
For comparison, the Tolifo PL100 RGB Palm Light I have been using as my main video light requires me to be at about 70% power at 1/100th of a second to get a clean exposure. The C150X Lite at 100% needs 1/4000th. That is the kind of difference you only really notice when you are working in light-hungry conditions like paper reversal, but when you are working in those conditions, it is the difference between being able to take a portrait and not.
Practically: with the diffuser and grid both attached, you lose roughly two to three stops of that output. That is still plenty for everything I want to do.
Fan noise
A reasonable concern with a 150W light: how loud is the cooling fan? Modern professional lights need cooling because LED output at this power generates heat.
I tested by holding the light next to my video microphone with the fan running.
It is quiet. Genuinely quiet. The fan kicks in after a few minutes of full-power use, but it has not interfered with any audio recording I have done while the light is on. For video work where the light is on for extended periods, this matters a lot. The Sirui clearly engineered the cooling properly.
What I have actually used it for
I have been testing this light for a few weeks before writing this review. The shoots I have used it on:
Portrait box camera shoots. Early frames from the ULF DIY portrait box camera, where the ISO is in the 0.6 to 0.9 range and every bit of light matters. The C150X Lite at full power got me into shutter-speed territory that made portraits actually viable.
Stenopeika Minutero 2.0 testing. The kitchen portraits of my daughters for the Minutero 2.0 review were lit by this light. The kit was the primary light source for the whole shoot.
General studio work. Where I would previously have used the Tolifo or other lower-power options, the C150X Lite has become the default. More power available means more options for modifier choice, distance from subject, and aperture flexibility.
The flash versus constant light debate
This deserves its own section because it keeps coming up.
There is a school of thought in professional photography lighting that says you should always use flash and strobes for serious work. The argument is that strobes give you cleaner, more controllable lighting and that constant lights are a hobbyist tool. This is mostly true for normal-ISO photography.
For paper reversal, with an effective ISO of around 0.9, it falls apart. I have tested flash extensively (the flash with paper reversal article covers this in detail). Even with multiple high-power strobes firing simultaneously, you cannot put out enough light in a single pulse to expose a paper reversal print properly. The process needs accumulated light over time, which is what constant lights give you and what flash by definition does not.
So for this specific application, constant light is not a compromise. It is the right tool. And a 150W constant light with the output the C150X Lite has is exactly the kind of constant light you need.
What I like
The power. 150 watts is enough light for paper reversal, which most lights cannot match. For general photography and video it is overkill in a useful way.
The build. Solid, professional, feels like a tool that will last. The miniature Bowens mount is well engineered.
The included modifier. The QR40 softbox with grid is a genuinely useful piece of kit on its own, and including it in the package is excellent value.
The fan. Quiet enough not to ruin audio recording, even at full power for extended periods.
The power options. D-Tap, V-Lock compatibility, USB-C, included battery handle. Flexible.
The price. Not cheap, but well below the genuinely pro-level alternatives that would offer similar specs.
What I do not like
The setup time. This is not a fire-and-forget light. You assemble the handle, attach the cable, mount the modifier, screw in the diffuser, attach the grid. It is more involved than the simpler handheld panels I have tested. The payoff is the power and the modifier quality, but if you want a light you can grab and go, this is not it.
The weight when handheld. The intended use case includes mobile, handheld work. In practice the assembled rig is too heavy to hold for long. You will want a stand or a grip helper.
The miniature Bowens mount. Means you need the adapter to use full-size Bowens modifiers. Not a deal-breaker, but a small extra cost.
Who this is for
If you do photography or video work that demands real output and you want a single light that can serve in both contexts, the C150X Lite is an easy recommendation. It is more powerful than the casual end of the market and less expensive than the genuinely professional end. Sweet spot.
If you are doing low-ISO work like paper reversal, alternative processes, very long exposures, or any other light-hungry technique, this is one of the few constant lights I have used that genuinely has enough output to be useful. If that is your work, get one.
If you just want a small fill light or a vlogging key, this is more light than you need. Save the money and buy something simpler.
You can find the Sirui C150X Lite at the link, with discount code Davis5 for 5% off. The QR40 softbox is available separately if you want to add it to other Sirui lights.
Big thanks to Sirui for sending the kit. This light is staying with me. Two upcoming articles will feature it heavily: the ULF portrait box camera shoots and the Stenopeika Minutero 2.0 testing coming next.