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The author undertook this review with no affiliation to Marelux and no financial incentive. Marelux sent the author a pair of Apollo III 2.0 strobes for testing on a short-term loan basis. It was agreed that the author would provide an honest review, the only clause afforded being that Marelux could decide whether or not to make the author’s views public.
 

A green turtle flies through a baitball: The Apollo III 2.0 produces wonderfully soft light and accurate colors when using the wide-angle warming diffusers
 

When Marelux debuted on the scene, they started out with a line of housings and, since then, have expanded into just about every genre of underwater photography gear: housings to optics to monitors to strobes. Marelux’s alpha strobe model is the Apollo III 2.0. With this latest version of their top-of-the-line flashgun, Marelux squarely aims to compete with the likes of Backscatter, Retra, Kraken, and AOI, to name a few.

It is useful to understand my history with underwater strobes, as this is the base of experience I will use to compare with the Marelux Apollo III 2.0 strobe. Over the last 10 years, I have used the Sea&Sea YS-D1, Sea&Sea YS-D2, Inon Z-240, Inon Z-330, Retra Flash Pro X, and ONEUW ONE160x. At present, the main strobes I use are the aforementioned Retra and ONEUW models. So, with that backdrop for context, how did the Marelux Apollo III 2.0 stack up?
 

A Game-Changer for Continuous Shooting Underwater with Flash

Headline Summary

• Marelux has built a strobe that aims to introduce two innovations to the market: wireless flash triggering and much improved continuous shooting performance.
• The continuous flash triggering is jaw-droppingly good, completely outperforming my existing strobes.
• To benefit from this, you must make use of their MTL mode and use this as your default configuration.
• The wireless flash triggering is good but not 100% reliable. I would still rather rely on fibre-optic cables.
• The overall performance of the strobe in terms of power and light quality feels good. I could not easily notice any difference versus my existing strobes. Longer-term testing in more situations and locations will reveal more on this.
• The light diffusion could be improved. My Retra Flash Pro X strobes cast light in a far softer and more even way.
• The battery reserve is excellent.
• The ergonomics could be improved and be more intuitive.
• For photography that involves fast-moving behavior (e.g., baitballs, diving gannets or macro animal behavior), the continuous shooting of the Apollo III 2.0 may help you capture shots you might otherwise miss. It could also be especially useful for continuous shooting in split-level imagery, which requires a closed aperture and higher flash power.
• For much of the underwater photography I do, the Apollo III 2.0 would be a very useful addition.

Reef scenics are easily handled by the Apollo III 2.0 and the color temperature with the warming diffusers is quite pleasing, especially in tropical waters

Build and Initial Impressions

The Apollo III 2.0 comes in a fairly large, protective packaging cube with foam inserts. This offers a reassuring way to transport the strobes—though at times luggage restrictions might preclude me from traveling with the strobe in cubes as two of them takes up considerable space in the suitcase. Nevertheless, this is a nice touch and one I personally have not yet seen from any other strobe manufacturer.
 

The Apollo III 2.0 comes in a nice carrying case with a custom cut foam insert for protection. While I wouldn’t necessarily travel with the strobes in this case, it is a nice touch that this is how they’re shipped—and it is a safe spot for storage
 

The layers of protection continue with special rubber covers for each of the Lumilink (more on this later) receivers on the strobe, and a screwed-on plastic cover that protects the dials on the back of the body. These features are also different to any other underwater strobe I have handled. The protective cover is a bit fiddly to put on and take off, but likely you would only find yourself doing so when storing or packing the strobe.

The Apollo III 2.0 has an industrial, high-quality feel: metallic and sturdy. The weight and size of the Apollo III 2.0 is not insignificant—comparable to the weight of the ONEUW ONE160x and only moderately shorter in length. The downsides of course are the added weight for travel and the the size of the flash can make it more cumbersome to slot into tight lighting setups when space is at a premium. The upsides of a larger strobe usually come in the form of quality of light, strength of light, and superior battery performance.

The front of the strobe has three rectangular flash tubes; it does not use the circular tube design that has become popular among high-end strobes. I pressed Marelux on their decision to use the triple rectangular tubes versus circular: According to Marelux’s testing during product development, the addition of a high-quality diffuser matches the light quality produced by circular tubes. Marelux preferred to use straight tubes, as they believe they have a longer lifespan and are able to deliver greater light output, as well as opening up possibilities for continuous flashing. My own side-by-side testing of strobes would yield more insight into this aspect and is continued later.
 

A great challenge in underwater photography is “disguising” the light to make it look natural. With a wide, soft beam, the Apollo III 2.0 makes this quite easy to achieve
 

The battery compartment has a large unlocking device, which would be easy to use even with numb and cold hands. Reassuringly, the battery compartment features a double O-ring design and the compartment is sealed off from the rest of the strobe, so if there is water ingress, it is not a death knell for the strobe unit.

The Apollo III 2.0 is powered by three 18650 lithium batteries and uses a color indicator light to show how much charge remains. The indicator light is easy to see and keep track of: blue (80–100%), green (60–80%), yellow (40–60%), purple (20–40%), red (0–20%). I didn’t push the strobes too hard in terms of number of dives and flashes, but I never went below a green light. Battery life is a strong point for these strobes and an area of great reassurance when shooting, especially for long, full days.

Marelux supplies fiber-optic cables with the Apollo III 2.0, but strangely, they aren’t the standard coiled design of other fiber-optic cables. Instead, while they are built well and feel extremely sturdy, they are short and less bendy—you have much less slack in the cables for maneuverability and adjustability.
 

The author cruising over a reef in the Philippines with his Nauticam rig and dual Marelux Apollo III 2.0 strobes

Functionality and Ergonomics

The ergonomics of the Apollo III 2.0 are a bit of a mixed bag. The power dial increases in increments from 1 to 12; the numbers are written in a small font that may be difficult for some people to read. The dial shifts quite easily between positions and I would prefer if it did so with a harder stop at each power level to avoid any accidental changes. A firmer stop would be even more welcome when your tactile sensitivity is reduced through cold water or usage with gloves.

As with most strobes on the market, the Apollo III 2.0 features a central focus light with both white and red modes. Activated by pushing in on the mode button, I was initially confused as this is different than other strobes I’m used to, but once familiar with it, it becomes second nature to turn on the focus light. 

A gripe I have with the ergonomics and design is that the side dial functions are listed on a different area to the actual stops on the knob. When you change functions on the strobe, you must angle the strobe towards your face to see what the dial position correlates to. Of course, with usage over time, you will become familiar with how many clicks it takes to get to each strobe function, but it is an annoying learning curve. Eventually, I learned that moving the function knob all the way took me to MTL and two clicks took me to M. Speaking of modes, the Apollo III 2.0 features five separate modes: Test, M, Auto Sync, M-HSS, and MTL.
 

Reflective subjects are a great test of the light quality of a flashgun, as they can so easily be blown out. No issues whatsoever exposing these shiny jacks with the Apollo III 2.0
 

In order to improve the strobe’s performance when it comes to continuous shooting, Marelux designed the MTL mode. Unlike with other strobes, you must use the MTL setting for continuous shooting, not the M mode.

Typically, for my style of shooting, my camera would always be in continuous shooting mode, giving the option of shooting a single frame, or when something exciting is happening, holding the shutter down and spraying a continuous stream of shots. On all other strobes I have used, I would be in M mode whether I was shooting singles or continuously. Marelux has changed that was of working, and the question is, do the advantages of MTL outweigh the obvious inconvenience of having to click between different modes?

In MTL mode, the power output is approximately half at a given power setting of what it would be at the same setting in M mode. For example, full power (12) in MTL mode has the same power output as half power (6) in M mode.

Seeing as I find myself shooting wide angle from 1/4 to 1/2 power on most strobes, with the Apollo III 2.0’s, this meant that I could usually get the power I needed for rapid fire shooting in MTL mode. While there is some mind-bending required to do the math between M or MTL, but this quickly becomes second nature.
 

Wonderfully soft and natural-looking light to illuminate this soft coral during a long exposure
 

There tends to be a lot of emphasis on the maximum power of a strobe. But I am just as interested in how low the power can go on a strobe. When shooting in dark, cold water environments, as I often do, you have to boost your settings to expose for the background environment, as this is lit by ambient light, not your strobes. Situations like these can be difficult to balance with strobes, as they often put out too much light and can be hard to control. Although I have yet to try the Apollo III 2.0 in cold water, I am excited about the fact that MTL means the low power settings on the strobe are even lower than M, so they may well be good strobes to use to create tasteful, delicate light during cold-water dives.

As far as maximum power is concerned, I found the Apollo III 2.0 had plenty for wide-angle scenes. In fact, I never needed to use anything like full power for my wide-angle images. I did make use of the strobe’s full output—flicking over to M and maximum power—when shooting a creative, slow-shutter image of a frogfish with a single strobe in the late afternoon. (The sky was bright but overcast.) To overcome the ambient light, these type of creative shots need very strong strobe power, and I was pleased with the result. In this case, I could make full use of my creativity and the strobe delivered what I needed.
 

A giant frogfish, bored with my antics and shockingly unimpressed with the Apollo III 2.0’s! Or maybe he’s gasping in shock at how impressive they are…

Light Color and Quality

Despite the aforementioned triple rectangular flash tube design, the Apollo III 2.0 produces a nice quality of light, comparable to strobes featuring circular flash tubes. For the duration of my time with the Apollo III 2.0, I used the 120° warming diffuser designed for blue water. The 120° dome diffusers are made of soft plastic and have a lanyard that can be removed if desired. I really like the rubber design: Operating in dynamic environments and on shoots from all manner of boats, I have a history of losing diffusers or cracking them. The lanyard and malleable design of the dome diffuser make this far less likely—and less costly!
 

Shooting upwards into bright conditions is a great test for a strobe’s power. No concerns here: I was easily able to light up this giant frogfish nicely, despite a bright surface above
 

Without a diffuser, the strobe has a rated color temperature of 6,200K, which is quite cool, but with the diffuser, I was pleased with the color balance I was able to achieve in my images. It felt neither too warm nor too cool in terms of white balance, which meant less time dealing with white balance during post-processing.

Quality of light is hard to quantify and is largely subjective. Ideally, I would like to spend more time with the strobes to give a more thorough and detailed assessment of the light quality and really get to know them intimately. That being said, I think that strobes are a tool, not a magic wand, and as good as a strobe may be, the role of the photographer in using that tool to control and shape the light is just as important, perhaps even more so. What I can say so far is that I felt like I could achieve the look I wanted with these strobes—which is a good sign.
 

The bright underbellies of sea snakes are quite easy to blow out. Fortunately, the Apollo III 2.0 produces a nice, soft touch, especially when diffusers are added

Continuous Shooting Comparisons

In my office, I performed side-by-side tests of the Apollo III 2.0 against my existing strobes—the Retra Flash Pro X and ONEUW ONE160X. I wanted to truly understand how the continuous shooting compared, and these tests also gave a good perspective on light color and diffusion.

Test Conditions:

• Strobes placed 1 meter from a wall
• Camera body, lens and settings remained the same throughout: Nikon D850, Nikon 16–35mm f/4 at 16mm, f/11, 1/250s, ISO 100
• Camera set to continuous high-speed shooting at 7fps
• Same fiber-optic cable used for all tests
• Batteries fully charged prior to tests. Panasonic Eneloop Pro AA batteries used with Retra strobes
• Diffusers used on all strobes:
  • 120 Degree Diffuser (Yellow) on Marelux Apollo III 2.0
  • Wide angle diffuser on Retra Flash Pro X
  • White diffuser on ONEUW ONE160X

Key Observations:

• Continuous firing: The Marelux Apollo III 2.0 clearly outperformed both the Retra Flash Pro X and ONEUW ONE160X, maintaining continuous delivery of light even at higher power outputs.
• Light diffusion: The Marelux Apollo III 2.0 appeared to diffuse light less evenly than the Retra Flash Pro X. I was impressed by the Retra’s wide and even light diffusion. I felt the light diffusion between the Marelux Apollo III 2.0 and ONEUW ONE160X was comparable, meaning that this is not purely related to the use of straight or circular tubes.

Marelux Apollo III 2.0 test
 

ONEUW ONE160x test
 

Retra Flash Pro X test
 

It’s important to note that these tests were primarily run to measure continuous shooting performance. Crucially, the brightness of the beam may impact our perception of the softness and fall-off of the light, while the power level may also impact the spread and smoothness of the beam. In addition, shooting through water rather than air may also yield different effects in terms of light dispersion.

This testing really opened my eyes to the potential of the Marelux strobes for fast-action work especially. Imagine yourself witnessing a moment of fast-moving hunting behavior underwater: With the Apollo III 2.0 strobes, you could fire continuously and stand a far greater chance of capturing the peak of the action. It could also be applicable in macro behavior scenarios where a lot of strobe power is needed. In addition, I would find it useful for split-level imagery, where we naturally close up our aperture and need higher strobe power—by shooting continuously, we stand a better chance of bagging the perfect frame.

To be sure, continuous firing is a specialist application that will likely be of less concern to most underwater photographers, especially those who focus primarily on more stationary subjects, but for me it is a potential game-changer, as I spend a lot of time photographing big animals and fast-moving pelagic scenes.

Wireless Flash Triggering

With “Lumilink,” Marelux has introduced an intriguing new feature to their strobe line. On the Apollo III 2.0, there are two prominent receptors located on either side of the strobe head that offer you the opportunity of eschewing fiber-optic cables to trigger the strobes. To make this work, you need a Lumilink signal device, which attaches to the top of the housing where the fiber-optic cables normally go.

Press and hold the power button on the transmitter for two seconds to turn it on. Then, to make the connection between the strobes and the transmitter, press and hold the strobe’s mode knob for two seconds; you will hear four beeps, indicating the wireless trigger mode is activated.

As far as triggering goes, Lumilink works perfectly as long as the the transmitter has a clear line of sight to the receptors on the side of the strobes. This is very sensitive: Imagine a straight line going from one to the other. I had instances where I adjusted the strobe position slightly and the signal was then blocked by a strobe arm, meaning it did not fire.

Fiber-optic cables trigger the strobes 100% of the time with the mild inconvenience of having a physical connection. Lumilink fired the strobes maybe 90% to 99% of the time, but suddenly I had to worry about whether the connection was intact. When shooting underwater, I need to be able to quickly adjust my strobe positions without wondering if the strobes will fire or not. Personally, I prefer to have a cable and 100% certainty, rather than a wireless transmitter and dealing with the worry.
 

Lumilink is an interesting innovation and could be quite useful for certain off-camera lighting applications
 

Perhaps the most intriguing potential use for Lumilink is triggering off-camera strobes. In a pool, in the very late afternoon, in relatively low light, I tested the connection and found that the furthest distance I could successfully fire the strobe from was about two meters (around 6.5 feet). I was a tad disappointed, as I had hoped to be able to have much more distance between myself and the strobe and still trigger it. Marelux says that the possible distance for a Lumilink connection increases in darker environments, and this may very well be true, but as of this writing, I did not have the opportunity to test this myself.

Off-camera lights and flashes, especially in wide-angle photography, usually work best when you hide the light behind a person or feature. Since Lumilink relies on direct line of sight with the strobe receptor, this type of use is also compromised, as you can’t hide the strobe and trigger it. I’d love to see Marelux develop a receptor that could be attached to the strobe via a cable. This would allow you to place the strobe wherever you choose while the receptor would be discreetly placed within communication distance of the Lumilink transmitter.

I feel Lumilink, as it stands, has more value in macro photography pursuits. For off-camera snooting, whereby the strobe could be detached and fired with creative lighting effects but within close proximity to the camera—and being careful to ensure the transmitter and strobe can “see” each other. In the past, when photographing fast-moving animals like juvenile boxfish, my partner Jade and I have also swum together with one of us shooting while the other handled lighting with a detached strobe and snoot. Lumilink might be used for this kind of work, too, though you would have to be very vigilant about the line of sight for triggering.
 

The Apollo III 2.0 has plenty of power to light a big baitball, and a nice enough light quality to not blow out the shiny silver fish

Final Thoughts

It is a truly wonderful time to be a strobe fanatic. That Marelux has managed to create a strobe that can hold its own against many of the high-end flashes on the market is quite impressive, especially when you consider they are also making housings, ports, optics, and numerous accessories. The Apollo III 2.0 is a legitimate high-end flashgun, capable of producing world-class images. It has its quirks, but it is rare that any product doesn’t. While they aren’t cheap, for those wanting to invest in a pair of capable strobes, the Marelux Apollo III 2.0 deserves some serious consideration. I look forward to continuing to have them in my underwater lighting arsenal.
 

About the Reviewer: Henley Spiers is a renowned underwater photographer, writer, and expedition leader who has fast become one of the most highly decorated wildlife image-makers in the world. An avid waterman, Henley is passionate about all aquatic realms, from storytelling marine protection in the frigid waters of Scotland, to venturing 500 metres deep on a scientific mission in the Indian Ocean. Whether it be swimming alongside hunting orcas or witnessing the feeding behavior of tiny blue sea dragons, Henley has a proven ability to deliver the images which do justice to the wonder and threats faced by the natural world. Henley was honored to be the first ever Storyteller in Residence for Oceanographic Magazine. www.henleyspiers.com