Retra Pro Max II strobe: detailed field review

Over the past eight years, Retra Underwater Technology (“Retra” for short) has earned a solid reputation as a manufacturer of high-end underwater strobes. From their early days producing one of the first optical snoots (the Retra LSD, 2011) to launching the original Retra Flash in 2017, the European company has steadily refined both the electronics and ergonomics of their designs.

In this article, I’m reviewing the fifth generation of their flagship model—the Retra Flash Pro Max II (or “Pro Max II”), which started shipping in July 2025. My findings are based on 82 hours of shooting over four months in Australia’s temperate and tropical waters, by day and night, on subjects ranging from super-macro critters to manta rays, taking over 14,000 photos over this period. 

Acknowledgements: the author thanks Retra for supplying a pair of Pro Max II strobes for the purpose of this review.

This review was first published on DivePhotoGuide.com in December 2025.

Review Index

• Quality of light & the evolution of Retra Strobes
• Wide-angle photography with the Retra Pro Max II
• Macro performance
• TTL & HSS
• Battery life
• Recycle time
• Thoughts on AA batteries
• Form factor & ergonomics
• Enhanced snooting via firmware: introducing the PLT mode
• Maintenance & flood resistance
• Sustainability, durability & price
• Conclusion
• Pros & Cons
• About the reviewer

Quality of light & the evolution of Retra strobes

I had a taste of the original Retra flash (gen 1) during one trip in 2018 and immediately placed a pre-order for the then-forthcoming Retra Flash Pro, which promised further improved quality of light via the introduction of a circular flash tube, while doubling down on the sturdy & ergonomic design which I loved on the first generation Retra.  

When my two Gen 2 Retra Flash Pros arrived in 2020, they quickly became my workhorses—I loved their very wide beam, soft light, gradual fall-off from the center, and the slightly warm colour temperature (4900K natively, enhanced to 4400K with Retra’s wide-angle diffusers). These attributes together make up what photographers loosely call “quality of light”, and Retra had nailed it.

I highlight the Gen 2 light quality because generations 3 (Pro X) and 4 (Pro Max) have maintained a very similar light output, while bringing gains in power-efficiency gains (Gen 3 and 4) and ergonomics improvements (Gen 4). I’ll take this chance to clear a common misconception: you can’t measure how much light a strobe emits by looking at its power rating in Watt.seconds (W.s): that number only tells you how much power the strobe consumes, how much it produces depends on how efficient the design is. By optimising the electronics (inside the strobe) and the optics (front of the strobe), Retra has managed to progressively improve battery life & reduce recycle time, while using the same AA-sized NiMh rechargeable batteries. 

For the fifth generation, Retra looked for a way to increase brightness meaningfully, without tanking battery life. The result is the Pro Max II, featuring a subtly redesigned, slightly more focused and much brighter beam, with a claimed +65% increase in light output. Retra told me the native beam was so wide in previous generations that diffusers wouldn’t make such a difference (aside from softening the light and changing its colour temperature), and many Retra users would shoot their strobes without them. With the Pro Max II, you do need diffusers for the widest beam, but you now have a slightly tighter beam on hand (with diffusers off), whenever you want the light to travel further, e.g. for big animals or distant scenes.  

Retra does not publish a beam angle figure, which I’m told is hard to measure when the edge of the beam is so soft. In practice, I find it wide enough to give room for error in strobe placement, yet not so wide that backscatter becomes unmanageable in average visibility.

On that note, if you’re getting too much backscatter on your photos, check my underwater lighting course for guidance on how to position your strobes and get clearer photos.

Wide-Angle Photography with the Retra Pro Max II

For wide-angle photography, I’ve mostly shot my Retras (the old Pros and the new Pro Max II) with their wide-angle diffusers anyways, because I value the warmer 4500K colour temperature, which makes water backgrounds bluer (after a straightforward white balance adjustment), and the extra softened light is a bonus, even though the I wouldn’t mind shooting them “naked”.

After four months of use, comparing shots taken with the gen2 Retra Flash Pro and its Gen5 replacement (both with diffusers attached), I can confirm that the Pro Max II maintains Retra’s well-known light quality, while delivering a significant increase in brightness. On large scenes, I usually sit in the 37–50% range, occasionally stepping up to 75–100% in clear water when shooting fisheye. For CFWA, I didn’t need that much power, stepping down the light in the 3-12% range—but the soft light remains highly likeable.

Macro performance

The Pro Max II is very well suited to macro too. With 17 power levels—from 0.3%, 0.7% and 1% up to 100%—you can dial in exactly what you need for tiny or highly reflective subjects.

It remains fully compatible with Retra’s existing lighting of accessories: meaning you’ve got access to a quality optical snoot (the LSD), macro rings, reduction rings, and reflectors (which can also work creatively for wide-angle). Besides, I am finding all these accessories have a similar buoyancy (slightly negative in saltwater), meaning you won’t imbalance your rig when swapping light modifiers during a dive.

I particularly like snooting with the Retra Pro Max II: the centred aiming light makes it easy to setup your lighting, even more so with the ergonomics enhancement that recently came via a firmware upgrade (more on this in the PLT section further below).

Snoots are a highly effective way to isolate subjects and reduce visual clutter, but they come with a learning curve. If you’d like guidance on getting the most from a snoot, this comprehensive snooting masterclass walks through practical aiming techniques, along with clear examples of common pitfalls and best practices.

TTL & HSS

The Retra Pro Max II really is a feature-rich strobe, offering supports for both TTL and High-Speed Sync (HSS).

I’ve shot in TTL mode sufficiently, to confirm it works reliably on both macro and wide-angle scenes, provided you use a compatible TTL flash trigger. That being said, like most experienced shooters I prefer controlling my strobes manually, but TTL can be genuinely helpful when task loaded, for rapidly swimming subjects, and for beginners, who get one less parameter to master. Learning to control your strobes manually isn’t that hard though, check my underwater camera settings course for guidance.

Unfortunately, when it was time to practice HSS I have been served poor visibility and/or cloudy days, so I don’t have a good illustrative shots but if HSS is an important functionality to you, I confirm it is supported by the Pro Max II.

Battery Life

Using the optional booster, the Pro Max II runs on eight AA batteries instead of four, improving significantly both battery life and recycle time. I shot exclusively with the boosters attached, and Retra’s claims of around 300 full-power flashes and over 1,000 flashes at 50% felt correct. A caveat: The aiming light takes a noticeable toll on battery life, so if you’re planning on having it turned on a lot (e.g., for snooting), expect to change batteries more frequently than normal.

The battery test function (five levels in 20% increments) has been refined over several generations & firmware upgrades, and I whilst it now seems dependable, but I’d always take some safety margin when deciding whether to swap batteries. The night before diving, if the strobe still showed 4 bars (>80% charge), I knew it would be good for whatever the next day of diving would bring. If It showed 3 bars (60-80% left) I would consider recharging if I expected taking more than 500 shots and/or using the aiming light a lot the next day. 

Bottom-line: the Pro Max II never felt short of battery, save for that one time where I had mistakenly left the strobe in battery test mode for 72 hours, only to find the battery depleted at the beginning of my dive. This was my mistake, but I wish the strobe could go in ‘sleep’ mode after a while. That said, Retra tells me this will be addressed by a forthcoming firmware upgrade.

Recycle Time

My biggest grievance with my Gen 2 Retra Flash Pros was their recycle time, which Retra has worked to shorten with every generation. The Pro Max II is rated to keep up with 60 fps at low power—which I couldn’t test (nor was very motivated to!)—but I did run a series of burst-shooting tests, at speeds which I found more relevant to real-life work. 

As with any strobe I tested, output decreases gradually during rapid firing as capacitors don’t have time to recharge fully. What matters is how smooth that drop is and whether the strobe skips frames. Impressively, the Pro Max II almost never stops firing unless you combine high frame rate with high power (e.g., 10fps at 50%), but of course, you still want the exposure to be relatively consistent across frames, so we’re looking for a smooth light decrease.

My test protocol: I burst-fired a Pro Max II at various speeds, using a portion of my kitchen wall as target (should have wiped it before…) and compared the resulting shots for exposure consistency, using both my eyeballs and scrutinising the histograms. 

This article would get very boring if I included every test shot, but here are a few examples showing the first 10 shots, at various settings (NB: I’ve changed exposure parameters between series, what matters is the consistency within a series).

NB: if you wanted to replicate those tests at home, make sure to submerge your strobe in water so it stays cool.

In real-life, I’d rarely shoot bursts for more than a second, usually taking up to 5 shots only, to capture the peak of the action. With that in mind, here are my practical take-aways:

• If I really need to shoot at 10 FPS: I stay at 2% power or below, unless the subject swims towards me (e.g. sea lion), in which case a progressive decrease in brightness can work well, and I would go up to 9% for brief bursts.
• 5 FPS suffice for most underwater action, which I’d use at up to 5% for static subjects and perhaps 19% for fast-approaching marine life.
• 3 FPS is my go-to burst setting when I need lots of power—up to 25–37%, accepting a visible drop in output across the burst.

Overall, the Retra flash has gotten better with burst shooting, being well suited for capturing macro and CFWA action, but for fast swimming big animals, strobes equipped with bigger NiMh or Li-Ion batteries still have an edge.

Thoughts on AA Batteries

Many new strobe manufacturers have adopted Li-ion power for good reasons: high capacity, high output, and compact size. Retra themselves will soon introduce Li-ion in the upcoming Retra Maxi, but for their flagship, they have continued with AA-sized NiMH cells.

Reachargeable AA batteries (Retra recommends Eneloop Pro) offer three advantages for underwater photographers:

1. They’re easy to find worldwide, should you lose or damage one.
2. They are airline-friendly, without the increasing baggage restrictions that apply to Li-ion batteries.
3. They are safer: batteries catching fire is a well-known risk with Li-ion batteries.

The downside, historically, has been handling lots of AA cells (8, to get the most out of your Retra flash) and maintaining two sets of double o-rings. Retra has made their users’ life easier with the Pro Max I/II: the booster and main battery compartment now are secured by the same pair of o-rings, which makes battery swaps faster. Combined with longer battery life, handling AA batteries is much less of a chore than on the Pro Max II than it was with my venerable Retra Flash Pro. I also carry two 8xAA smart chargers (one per strobe) so batteries get recharged quickly.

Form Factor & Ergonomics

For a high-powered wide-angle strobe, the Pro Max II is relatively compact—102 mm wide and 148 mm long (+25 mm with boosters). It is smaller than my old Retra Flash Pros thanks to the shorter boosters, and noticeably lighter (120g saving) and less negatively buoyant underwater.

The compact size makes strobe positioning easier, and the more neutral buoyancy means I don’t need to tighten clamps as aggressively—making lighting adjustments easier in the water.

The mode and power dials have distinct clicks and can be differentiated by touch: the mode dial is slightly taller. The digital display (introduced with the Pro Max I) shows both mode and exact power level, and is easy to read by day and night. Whilst I appreciate this feature, I miss the colour coded indicator that could tell me from a distance whether the strobe was fully on, off, or still in battery-test mode.

Enhancing Snooting via Firmware: Introducing PLT Mode

My only real usability issue was the aiming light button which I found it very stiff, so much so that I had to hold the strobe with my other hand so it wouldn’t wobble, when I was turning on & off this light, to aid with precise snooting. When I mentioned this to Oskar (Retra’s founder), he explained the button had been reinforced for durability but agreed the stiffness was not ideal. He proposed a solution that we brainstormed on, and two months later Retra released a firmware update adding the “Pilot Toggle Light” mode (PLT).

Using Bluetooth, you can update the strobe and enable PLT, which allows you to toggle the aiming light on/off and adjust its intensity via the very responsive power dial:

• Rotate one click up and immediately back → aiming light ON. Repeat to make it brighter.
• Rotate one click down and back → aiming light OFF

After three macro dives with PLT, I wouldn’t want to go back, and what started as a solution to a problem has become an advantage of the Pro Max II for snooting:

• No risk of messing the snoot’s positioning when turning the light on/off
• No need to overtighten clamps to prevent the above
• The power dial is intuitive to find by touch, so turning the aiming light on/off can be done by touch, without taking your eye away from the subject.

Maintenance & Flood Resistance

Very much to my liking, the Pro Max II is a low-maintenance strobe. The battery compartment’s two robust o-rings require only occasional lubrication (every 4–5 battery swaps), and they stay seated firmly when opening or closing the cap—reducing the chance of pinching or twisting.

A built-in leak detector monitors the battery compartment and triggers multiple alerts (audible alarm, flashing pilot light, displaying “LEAK” on the rear screen) if as little as 2 mL of water enters. Also, the battery compartment is isolated from the electronics, providing an additional layer of safety & meaning there’s a good chance the strobe will keep working after a flood (& proper rinsing/cleaning). While I haven’t needed this alarm, it’s nice to know it’s there.

Sustainability, durability & price

As underwater photographers, many of us have witnessed firsthand the impacts of global warming and pollution on our oceans. One way to minimize our human footprint is by choosing gear that lasts, reuse, and—as much as possible—repair or recycle.

When it comes to durability, I can vouch for the two second-generation Retra Flash Pros that have been my main strobes for over four years, enduring countless shore entries, bumping on all sorts of rocks and getting a fair amount of abuse. After four months with the Pro Max II (8,000 shots taken with one, 10,000 with the other one—the app lets you see that), it feels like they’re as tough as their older relatives, both having a monolithic aluminum body.

I haven’t needed to repair a Retra strobe, but the company has a reputation for being very responsive via email and for servicing every product they’ve ever made. They offer a standard three-year warranty, extendable to five years for a small fee, and—importantly—the warranty is fully transferable. This helps maintain strong second-hand value, providing peace of mind for the next buyer.

Seemingly like everything else, Retra strobes are getting more expensive with each iteration: A Pro Max II will set you back $2,100, or $2,300 if you want a booster. However, every shooter who upgrades usually lets go of a previous version second-hand, at a good discount, meaning older Retra strobes can be had at a sweeter price, possibly with some warranty coverage left.

Conclusion

The Retra Pro Max II is a premium strobe capable of handling everything from super-macro to large wide-angle subjects. With this fifth generation, Retra has significantly increased brightness while preserving the light quality that made their reputation (you do need diffusers for the widest & most progressive beam).

Battery life is now excellent, recycle time is sufficient for most underwater subjects (though not class-leading), and everything runs on 8x AA Eneloop Pro batteries that are affordable, easily replaced, and airline-friendly. The Pro Max II remains fully compatible with Retra’s accessories, so you can reuse all your lighting modifiers, if upgrading from a previous Retra flash.

I have no doubt that we’ll see a 6^th generation of Retra’s flagship strobe one day—possibly with lithium batteries, possibly not. But if you choose to invest in Pro Max II strobes now, the long warranty, robust construction, and strong second-hand value mean your investment should hold good resell value, should you be tempted by an upgrade down the track. 

Pros & Cons

Pros:

• Superlative quality of light, especially with diffusers.
• Abundant battery life 
• Excellent ergonomics means you can control your strobe by feel. 
• The new PLT mode lets you toggle the aiming light on/off, without wobbling the strobe: great for precise snooting.
• AA batteries are easy to travel with, and the redesigned booster means handling 8 of them isn’t as cumbersome as before. 
• Excellent recycle time, for an AA-powered strobe.
• Only slightly negative in saltwater.
• Robust design proven in time.
• Long 3-5 years warranty, transferrable to a new buyer.

Cons: 

• Expensive strobe.
• Burst shooting limited to close subjects.
• The battery will be emptied if you leave the strobe in “test” mode by mistake – Retra is working on another firmware upgrade to address this.

About the reviewer

Nicolas Remy is an Australia-based pro shooter and founder of online underwater photography school and community, The Underwater Club, with members in 26 countries. He serves as an ambassador for Mares and Nauticam, and chairs the jury of the prestigious DPG Masters photo competition. Nicolas’ images have been widely published in print and digital media, and have won over 40 international photo awards. To see more of Nicolas’ work or browse his upcoming workshops, visit: www.nicolaslenaremy.com.