SIRUI 18° – 36° Projector Zoom Lens for COB Lights – Review

by Graham SheldonSeptember 23^rd, 2024

SIRUI, formerly primarily an optics manufacturer, has lately added lighting to their lineup of affordable cinema-focused products. We took their 18–36 Degree Projector Lens for a spin in this field review, and if you’ve never used a projector lens accessory (sometimes called a Spotlight or even a Leko for shorthand), you’ve been missing out! Let’s jump in.

Over the years, I’ve tried many projector accessories such as traditional Leko lights on theatre, film, and television projects. Projector accessories are incredibly useful, allowing you to throw varying degrees of beams of light far or short distances with incredible precision. You could bounce this type of light for a flattering key, use it as a hard-edge light, or light up a specific art object in the background without much trouble.

As I mentioned in the beginning, there is more than one name for the projector accessory. Ellipsoidal reflector, Leko, spotlight, and “Source Four” (a brand name) are a few. For the rest of this article, we will stick with “projector”. In the past, projectors took a Tungsten bulb (500-750 watts), and gel was often required. To this day, you can find relatively affordable projector tungsten fixtures in theatres and event venues worldwide. They are also a great starting light for students (remember to use gloves!).

Now, we live in a world increasingly dominated by LED fixtures, but we still want both the quality and control of the tungsten fixtures we’ve used for decades. Enter the 1.67kg/3.7lbs SIRUI Projector Lens accessory priced at $429 with a beam angle between 18 and 36 degrees.

Making an accessory like this is actually very tricky because it requires lots of carefully placed glass elements, and if the COB fails to reduce heat, watch out, user. In fact, the last burn I received on a commercial job was from a projector accessory (not from SIRUI). Just because we are moving away from hot tungsten lights doesn’t mean you can’t get a solid burn from LED lighting. It’s also a good reminder for me!

The fact that this accessory has a variable beam is one of the features that makes it stand out from competitors who mostly rely on fixed beam angles for their projection accessories.

As I went into testing for this review, I was optimistic that SIRUI (a company that knows something about lenses and glass and how they interact) would be perfect for making an accessory like this.

Initial Impressions

Not all lighting accessories listed as Bowens mount compatible can be used with all Bowens mount fixtures, just as lens flange distance can vary in compatibility between different camera systems and mounts.

With that in mind, SIRUI claims that this projector accessory will work for Bowens lights 200 watts or less. Unfortunately, I’m not able to test this accessory with every sub-200-watt cinema light on the market. So, my advice is to take care when purchasing and ensure you test at home before taking it into the field on a paid job (good advice for lots of tech these days). For this review, I’ll primarily use the $223 SIRUI CS200B for my testing, as well as a few Aputure, NANLITE, iFootage, and amaran fixtures.

The SIRUI projector (occasionally referred to as P1836A by the company) ships in an excellent, sturdy, labeled hard case with plenty of foam protection in every direction. I would love it if SIRUI took this solid packing approach to more of their products. For example, the SIRUI CS200B Bi-Color LED Monolight ships in a simple cardboard box that, unfortunately, you must replace with another sturdier case.

Overall, the accessory is smaller than some projectors I’ve used in this category, and that initially concerned me a bit with the heat handling, but more on that later.

SIRUI includes 15 gobo patterns, 3 color filters, and a gobo holder inside the core kit. You can also purchase the SIRUI CS200B + the projector accessory as part of a package deal, so that may be worth your time if you are also looking for a suitable light.

SIRUI Projector Lens – heat dissipation

A hollow aluminum alloy design rings the projection accessory to allow heat to escape. Still, the actual attempt at tackling the ever-present heat issue is a separate, primarily plastic battery-powered fan unit that connects by magnets to the side of the unit.

A few things about the detachable fan unit: The battery is charged by a USB-C cable (not included) and doesn’t appear to be weather-resistant. You must also remember to turn it on using the separate power button. There is no warning if the battery dies, so it’s up to you to keep an eye on it and recharge the fan when needed. Thankfully the fan does work with a USB-C cable inserted while charging, so you could keep the fan running without delaying your shoot. Four lights marking quarter increments on the side of the fan indicate if the fan unit is charged or not.

Early marketing materials for this accessory never mentioned the fan, and thus, I’m assuming this was a later addition as the product came to market. That’s not necessarily a bad thing, as having an electronic fan is better than having only passive cooling, and the fan unit doesn’t add significant noise that could be picked up on a mic.

The fan removes heat, and it’s reminiscent of the fan accessories created for various mirrorless camera systems on the market. I know it’s a big ask, but my hope is that we can move to a universal system of electronic communication between lights and accessories so that something like this fan unit can be triggered on and off and powered from the light itself rather than an internal battery.

Granted, this electronic communication solution isn’t a novel idea, and we are already seeing electronic contact points being added to lights by competing manufacturers such as ARRI, Aputure, Nanlux, and others. Hopefully, SIRUI will consider adding something like that in the future, too.

The results

SIRUI’s projection accessory works well, provided you stay within the 200-watt guidelines and use the fan unit (especially in hot environments). Remember, I’m not testing this with every sub-200-watt light on the market, but in the testing I did, I didn’t notice weird aberrations around the edge of the beam, and the cuts of light you can make with the four shutters are very clean. This quality of light is also consistent throughout the entirety of the range from 18 degrees to 36 degrees — not an easy thing to do.

I did see light bleed out of the sides of the accessory (mainly from the heat sink area), but it is minimal. A small knob lets you focus or de-focus the instrument to explore different looks for the gobos or a light beam.

The variety of gobo options is helpful. While all of them might not be useful on every shoot, gobos like window blinds and different foliage types can be widely used on various projects. There are also fun options like bird wings and more abstract shapes. The included color filters are also potentially helpful if you aren’t working with color-capable COB fixtures.

As I mentioned, I used the SIRUI CS200B in conjunction with the projector, and this pairing gets hot when the light is at 100%, but not uncomfortably so when the fan is on during summer filming in California with no AC.

Final thoughts

The $429 price tag for the SIRUI Projector Lens is competitive; it comes with a variety of gobos, and its variable beam angle makes it stand out. The case it comes with is fantastic. All those positives outweigh a fan unit that feels like a bit of an afterthought.

SIRUI’s move into other product categories like lighting continues with some real success stories at filmmaker-friendly pricing. I am interested in seeing what the company comes up with next.

Head over to their Kickstarter page to get more information.

Please note that this review contains affiliate product links for SIRUI’s Projector Lens campaign. As with any other crowdfunding campaign, we advise you to carefully read the platform T&C as it is not a shop! SIRUI, on the other hand, had several very successful campaigns in the past, so obviously they can deliver.

What do you think? Will you be adding the new SIRUI Projector Lens to your kit? Let us know in the comments below!