Long Term Review of the Retra Maxi Strobe

January – July 2026

Retra Underwater Technology very generously provided me with a pair of their new Maxi strobes for evaluation. I've been shooting the Backscatter HF-1 for over a year now and have publicly made comparisons with Retra's strobes. To be perfectly honest, I have been critical of Retra's highest-end Pro Max and Pro Max II strobes due to their relatively high price compared to the HF-1 and their use of older AA battery technology. I consider AA power cells outdated in the lithium-ion era, resulting in limitations to core features like recycling time, video lighting, and run-time.

The new Maxi strobe seems to have answers to each of these critiques. I appreciate their confidence in allowing me to consider their new product.

Retra included the required batteries, and two sets of their reduction rings and Wide Angle / 4500k color diffusers. I am very happy to have these accessories, as they match what I routinely use with the Backscatter HF-1 strobes.

It is an exciting time in the underwater photography market, with a lot of new lighting options showing up over the last two years. Backscatter started this momentum with their HF-1 high-power, wide-angle strobes. Adopting lithium-ion batteries in a market long dominated by AA-powered cells, the HF-1 brought a new set of capabilities to shooters: longer battery life, much faster recycle times, higher-power flashes, and 5000-lumen video lights, all in one package.

Starting in January 2026, the HF-1 got new competition when Retra Underwater Technology began shipping their new Retra Maxi underwater strobe. The Maxi meets or exceeds the HF-1 on most of the spec-sheet line items. It uses the same 21700 high-draw lithium-ion batteries. The Maxi provides an (optional) 6000-lumen video light. And it is compatible with Retra's range of accessories and add-ons like the LSD snoot, color filters, and reduction rings. Best of all, there is no more reliance on a massive set of 16 (or even more with spares) AA batteries and chargers needed to support two strobes on a dive trip.

I started writing this review back in January 2026 with some preliminary coverage of specs and some studio shots to explore some of the features, light output and performance. This included comparison with competing products. I shared the pre-review on the WaterPixels.net forums and used that as a sounding board to get ideas and feedback for areas to explore and methodology for the testing. Some of the material in this full review came from that initial effort.

Reliability might be the single most important feature of an underwater strobe. Specs, performance, and price of a product are all important details. But underwater photography is an expensive hobby, and high-end strobes are a serious investment. Most UW photographers take their gear to remote locations and drag it through challenging environments like suitcases, airline cargo handling, hot and humid tropical environments, the occasional wet and freezing-cold environment, and yes — even the depths of the ocean. Reliability cannot simply be measured by a casual "specs comparison" in a review. You have to use the product for an extended period to form a meaningful opinion.

We all want to know that an investment in new gear is going to stand up to the rigors of heavy and repeated use, all the while putting out high-quality light, at high speed, and without skipping a beat. And if it does throw an occasional sprocket, can you expect any support from the vendor?

My goal was to provide just such a long-term review, and I hope that I have succeeded. Since late December 2025, I have taken a pair of the Retra Maxi strobes on just over 100 dives. Just under half of the dives were in the tropical conditions of Raja Ampat, Indonesia, where I shot the Maxis on 46 dives over 16 diving days. The other 55-60 dives spanning 6 months were split between shore dives around Puget Sound near Seattle, and boat dives in several locations on Canada's Vancouver Island. These 100+ dives cover a wide range of conditions that will really put the Maxi strobes through their paces.

Indonesia had surface temperatures of around 30°C (86°F) and water temperatures about the same. The bright conditions and clear water create an environment where your strobes are often operating near their maximum power to light up colorful reef scenery. Maximum light output, battery life, and thermal stress are all very important factors in this sort of diving. High frame-rate captures of speedy critters like juvenile sweetlips, sharks, and mantas are often critical to getting the shot.

The Pacific Northwest of the USA and Canada have a whole different set of conditions. Surface temperatures below 0°C (32°F) and water temperatures in the 8-10°C (46-50°F) range are the norm. Shore diving on rocky beaches, high silt surf conditions, and strong currents represent significant challenges to physical durability. Lower light conditions and heavier particulate in the water column present more difficult lighting conditions than the tropics. Power and light output requirements tend to be in the ¼ to ½ power range. Reduction rings and warming filters are almost necessities to get the best possible images. Spotting lights get used more often and present a strain on battery life, especially if using a snoot. I tend to use a snoot far more often in the PNW, as the lower ambient light makes snooting much more effective. In the tropics, ambient light conditions tend to drown out even the brightest spotting lights, making the use of a snoot a more frustrating endeavor.

Build quality, reliability, troubleshooting, and support all ended up playing a big role in my consideration and appreciation for the Retra Maxi strobes.

The hardware lives up to Retra's familiar high level of refinement and precision in manufacturing. The Maxi's silver-gray aluminum construction and controls are directly comparable to the Max II strobes despite being sold at nearly half the retail price.

The engineering, design, and build quality of the Retra Maxi is immediately apparent. This is a solid and robust strobe made of what I assume is aluminum. The battery compartment is confidently sealed with two heavy-duty Buna rubber O-rings. Most other strobes on the market, such as the Backscatter HF-1, are sealed with thinner and more delicate silicone O-rings. I really like the Retra battery door design, as it is simple, easy to inspect and wipe clean, and pretty much foolproof in assembly.

One observation about the Maxi is that, unlike other strobes in its range (Retra Pro Max, Backscatter HF-1, etc.), it does not use a spring-loaded system to hold the batteries in place. Instead, the electrical contact on the battery door is a bent piece of metal that has some flex. Should that get bent or compressed, perhaps during travel or heavy use, the battery can rattle and lose contact. This happened with one of my strobes upon receipt. Fortunately, it was easily fixed by gently bending the contact. Retra let me know that they made a packaging change to prevent this during shipping. I did not have a repeat of this problem after months of use.

The onboard electronics of the Retra Maxi are also impressive. It has a self-test mode that checks the strobe on power-up and then displays the battery level in 25% increments with a colored LED. In the case of a battery-compartment flood, the strobe will detect the initial ingress of water and warn with a blinking cycle of red/blue on the indicator. Perhaps most importantly, the Maxi supports a Bluetooth connection to an iPhone/Android photo application. The app can report various metrics about the strobe, change some settings, and update the onboard firmware. This last capability really sets the Maxi (and other Retra models) apart from the competition. I have had other-brand strobes that needed to go back to the OEM for updates to address bugs and glitches. The Retra Maxi's ability to update the strobe in the field is a big win for customer support and long-term reliability.

Equally impressive are the ergonomics of the Retra Maxi controls. Perhaps uniquely among the strobes I have used over the years, the Maxi includes control knobs that are easy to use in thick dry gloves. Thank you! Beyond that, the knobs provide a tactile "click" as you turn them, making it easy to change power settings to known values without looking at the strobe itself. I typically have my strobes on long arms and positioned such that I can't see the controls. Being able to adjust the controls by feel is critical. If unsure about your current power setting, you can turn it to max and then back down 1, 2, or 4 clicks to find your desired output level. I do wish the mode knob was a different tactile shape than the power-level knob, but this is a minor personal preference.

The Retra Maxi has a powerful focus light with two power levels. This can be used as a focus light, backup light, or, most importantly, as an aiming light with a snoot. The Retra LSD snoot accessory has been a popular add-on with Retra users for years. What it does not have is a red-light mode, which is a small feature gap compared with competitors. This might be missed when used as a snoot, but generally it is not ideal to use your strobe as a focus light, as it puts too many limitations on strobe placement. I have always found the red lights are more practical on a dedicated focus light mounted on your camera housing.

In a first for Retra, the Maxi includes a very strong 6000-lumen video light. While not as bright as a dedicated video light, it is more than adequate for capturing the occasional high-drama underwater action scene. The power-level knob controls the output with 17 levels of brightness.

The Retra Maxi has broad TTL support and compatibility with various flash triggers. I don't use TTL and did not test this capability, so I won't comment further.

Before setting out on some initial test dives, I swapped out my Backscatter HF-1 strobes for the Maxis. My first dive would be limited to macro shooting only, as Pacific Northwest floods had wreaked havoc on the usually excellent winter visibility. Rather than my usual snooting setup for macro with the combo of an MF-2 + snoot and HF-1, I used the two Maxis with reduction rings. I shot with a Nikon Z8, 105z lens, and double diopters MFO-1 and Subsee +10.

My first dive ended up highlighting one of the standout features of the Retra Maxi — near-neutral buoyancy. And it made for a frustrating dive. Coming from the Backscatter HF-1, my system was configured with 4 Stix Jumbo floats on the inside arms and 16-inch (41 cm) ULCS float arms on the outside, plus a 370-gram (0.82 lb) macro-port float ring, which tends to balance out heavy diopters. The rig ended up being significantly positively buoyant, and it kept trying to twist backwards. After that first dive, I worked to dial in optimal buoyancy with the Maxis. I eliminated two of the Jumbo Stix blocks from the inner arms, removing 360 grams (0.79 lb) of floatation that I didn't need any longer. This ended up working well for both macro and wide-angle setups. The system was now slightly negative and balanced in the water with the strobes extended.

I took the following measurements with my full camera rig ready to shoot.

The Retra Maxi is larger and just 10 grams heavier than the Backscatter HF-1. However, it seems that Retra designed the Maxi with a buoyancy goal in mind. The weight in water is only 20 grams (0.7 oz), leaving it nearly buoyant in water. The Backscatter HF-1 is 250 grams (8.8 oz) negative in water, requiring more added floatation accessories to achieve a similar weight and balance in the water. In my experience, the size difference of the two strobes is negligible.

The Retra Pro Max-II strobe, the high-end AA-powered strobe, ends up being nearly the same length and weight as the Maxi once you add the battery boosters to it, running only 145g (0.32 lb) lighter and 1mm (0.04 in) shorter, but is 160g (5.6 oz) negative. (Without the booster, battery life and recycle times are greatly reduced.)

With underwater strobes, buoyancy is more important than size in my opinion, and the Retra Maxi really outperforms in this category.

As mentioned earlier, I evaluated the Retra Maxi strobes across about 100 dives and a diverse set of tropical and cold-water environments. Bright ambient lighting with clear blue water, dimly lit green waters, boat dives, shore dives, often with 3 or 4 dives a day. My highest shot count was 597 frames in one day. In total I fired the strobes in excess of 12,000 times on each of the two strobes. I occasionally shot video using the 6000-lumen video lights, mostly in 60-second captures, but no more than 5 minutes total during any dive.

The Retra Maxi strobes were consistently excellent in their performance and reliability across many dives.

One of the big advantages of lithium-ion strobes is the power and recycle times that can be achieved built on this technology. The Retra Maxi scores very well in both metrics. I will discuss both of these topics in more detail later in the review, but I'll share the summary up front.

The Retra Maxi is very powerful, slightly more powerful than the Backscatter HF-1. Even with most shots at full or half power (+4 to +3 on the power dial), the Maxi can fire 500 times without making a significant dent in battery capacity.

Recycle time is also excellent. I set my Nikon Z8 to 3 frames per second and left it there. The Maxi can keep up a consistent level of light at half power (+3 on the dial) at 3fps. Drop to +2 if you need to shoot faster than 3fps. I was able to take advantage of this speed for several unique subjects that were either fleeting fly-by encounters or were moving so quickly that framing was not possible. You won't always shoot so rapidly, but it is great to have the ability when you need it most — for example, on a black-water dive.

Using the Nitecore 6000mAh batteries recommended by Retra, I didn't drop below 50% remaining power and mostly stayed above 75% remaining by the end of the day. There were several days in Raja Ampat and Canada where I fired over 500 frames per day. I often used the +3 or +4 power levels in bright shallow reefs of Indonesia. This is between 50% and 100% power level on the strobes. (They also have boost mode, which I never used in the water.) Even when I shot several minutes of video with the full-blast 6000-lumen video lights, I didn't draw down below 50% battery power. On a few occasions I used lower-capacity 5300mAh Nitecore batteries and didn't notice any difference in battery life.

I charged the batteries at the end of each dive day while on trips. I have occasionally run the batteries for multiple days when doing single-dive days around home without issue. However, if the strobes are unused the following day, it's better to remove and recharge them, if for no other reason than to avoid losing track of when you last recharged. It is also not ideal to leave batteries in the strobe unused for extended periods of time (risk of battery leaks, off-gassing, drying out the O-rings and raising the risk of floods, etc.).

In summary, battery management is stress-free with the Retra Maxi. Pair it with a high-quality USB-C-based 4-cell 21700 charger. Packing four 21700 batteries makes end of day charging quick and easy on a dive trip. My focus and spotting light is an OrcaTorch D710v2 that also uses 21700 batteries. I use two Nitecore 5300mAh batteries for the spotting light, and these can step in as backup batteries for the Maxi should there be any complication with its dedicated batteries. In total, I only packed 6x 21700 cells and a couple of camera batteries. Powering the chargers is a 60-watt USB mini-brick, plugging in a 4x21700 cell charger, a camera battery charger, and a Shearwater Qi charger. Everything is Velcro-attached to a mouse pad, keeping things compact, organized, and lightweight.

Overall, the Retra Maxis have been extremely reliable. One hundred dives in and everything is still working 100%. The strobes are robust, well built, and don't show any significant signs of wear. I would not have any reservations about taking them on the most challenging or lengthy dive trips.

One detail that has impressed me is the battery-compartment seals. Most of my diving involves shore entry with very fine silt and sand in the water. The fine grit tends to find a way into every crack and crevice in your camera system. The back seal of my Nauticam housing often collects sand on the O-ring, for example. However, the Maxi battery seal O-rings do not seem to collect any sand at all. Any particles that might be accumulating are getting washed away during a rinse and soak in fresh water. On dive trips I find that my camera rig typically only gets about 60 seconds in a communal rinse tank, and that seems to be enough day to day. Battery-compartment flooding is one of the most common failure modes for strobes, so hopefully this design helps to keep it to a minimum. That said, be sure to remain diligent in your post-dive rinsing and soaking. Longer soaks and a good cleaning should take place at the end of any trip.

I did have two minor issues with the Retra Maxis during my Indonesia trip that are worth mentioning.

I encountered the first glitch at the end of a dive when I attempted to switch the Maxis off. One of the strobes would not turn off even with the switch in the off position. I turned them back on again, and both strobes continued to fire on demand, but the affected strobe could still not be powered down. After getting back on the liveaboard and getting everything rinsed off and dried, I went back to test the strobes again. The strobe remained powered on in the off position. I pulled the batteries to finally shut it off. Upon reinstalling the batteries, it functioned completely normally.

I sent a message to Retra via WhatsApp, explaining the problem and even including a video of the strange behavior. It turned out that Retra had a pre-release firmware update that they thought would address the issue. Even though I had never used the Retra Bluetooth connection option before, it was quite easy to download the app they sent me and flash the Maxi firmware on both strobes. Following the update, the Retra Maxis have never duplicated this problem. Retra has since released a few more firmware updates, but not for any issues that impacted me. The ability to update firmware directly on the strobe is a serious advantage for Retra. A software glitch like I experienced might have resulted in a product return on a less capable strobe.

I was happy to have this experience, as it provided firsthand experience working through a customer-support issue with Retra. I was very satisfied. I've seen and heard of similar experiences from other Retra users who successfully got useful assistance from Retra while on the far side of the world.

The second issue was probably not actually a Retra Maxi-specific problem. During another dive in Indonesia, one of the two Maxis stopped firing. Powering it down and up again sometimes got it working, but it mostly would not operate. After the dive I opened the strobe and swapped in another set of batteries, and all was fine. I polished all of the Nitecore battery contacts and used isopropyl alcohol to clean all of the strobe's electrical contacts as well. The problem never occurred again.

I have had this same issue with the Backscatter HF-1 and MiniFlash strobes in the past. Other photographers commenting on UW photography forums have reported similar issues on various strobes. I suspect that this is a generalized problem faced by high-power lithium-ion strobes. Even a small amount of corrosion or oxidation that builds up on battery contact surfaces during regular usage can reduce the voltage enough to impair functionality. In every case I've seen so far, simply cleaning off the contacts resolved the issue.

It's probably a good idea to make a point of cleaning the contact surfaces with a cotton swab or pad and a bit of isopropyl alcohol at the start and end of any major expedition.

The Retra Maxi has an excellent feature set and capabilities to take great photos in most situations. I've been very happy with the lighting quality of the photos that I produced with these Maxi strobes. These are powerful strobes, maybe the most powerful model on the market right now. It can light up a large reef scene better than any competitor. It has a very smooth beam pattern with a nice gradual drop-off toward the edges. The color temperature is cool but effectively warmed with a diffuser.

The sample images below should demonstrate the potential results more effectively than I can in words.

I am not a fan of the term "quality of light". It is too nebulous and nearly impossible to define, describe, or recognize. In my experience with many brands of strobes, almost all of them can take excellent-quality photos if used competently. That said, the power, capabilities, ergonomics, features, and recycle time of a strobe can make a significant difference in capturing or missing out on a great image. Arguments can be made for the shape, size, or color temperature of the flash tube and reflector. However, the reality is that most UW photographers tend to put diffusers and filters on their strobes, and diffusers will level the playing field by smoothing out the light beam and hitting a target color temperature.

In summary, the Retra Maxi has high-quality light output. Additionally, it has a core feature set with excellent battery life and fast recycle time that are going to help ensure that you don't miss a critical shot.

The Retra Maxi has a cold color temperature. You will probably need to buy the 4500K Wide Angle dome diffusers.

Perhaps my biggest criticism of the Maxi strobe is that Retra's own product page does not actually specify the native color temperature of the flash. Instead, they specify a color temperature of "~4500K (with WA diffuser)", which, by the way, is sold separately as an accessory. You may not need warming filters for macro shooting. For wide-angle scenes I found that the 4500K filter was effective in both clear tropical water and darker cold-water environments. Post-processing is much easier when the color temperature is a bit warmer in the RAW file.

My second criticism is that Retra does not offer a warming filter or diffuser that can be used in combination with reduction rings. In the more particulate-heavy cold water of the Pacific Northwest where I live, I find reduction rings very useful in avoiding edge glow and backscatter for wide-angle scenarios. The 4500K WA diffuser dome works well but can be challenging if used in combination with a very wide-angle fisheye lens. I ended up making my own reduction ring + color filter solution to close this gap.

Below is a set of sample images all taken with the Retra Maxi strobes in a variety of conditions: clear blue water of the tropics, high ambient light requiring full-power flashes, cold water with both clear and murky conditions, and a mix of subjects from super macro to super wide.

The following sets of images are comparison shots from the Retra Maxi, Backscatter HF-1, and Backscatter Atom. This trio of strobes has a lot in common, with a set of similar specifications, including:

For this comparison, each strobe was set to full power, half power, quarter power, and eighth power. The images were taken with a Nikon Z8, 8-15mm lens at 15mm, 140mm (5.5in) dome, at a range of 65cm (25.6in) from the wall. No filters or diffusers were used. The color temperature of all three strobes is similar at 6200K (Maxi), 6500K (HF-1), and 6400K (Atom). Aperture and ISO were f25 & iso50.

As I compiled the comparison images of brightness and coverage, it became clear that the "labeled" power levels between the Maxi and HF-1 really don't map to a common scale. After a variety of methods to visualize the data, I decided to rank the power levels from each strobe by their relative brightness. I used the brightness information from the Photoshop Histogram Information display to capture a common and comparable value. I am sure a professional light meter or similar instrument would be better, but I used what was available. The comparison images align well with the measurements, so I am happy enough with this methodology for simple comparison.

The HF-1 has a power level scale from +2, +1, Full, *, Half, *, Quarter, *, Eighth, *, Sixteenth, *. The +2 and +1 levels are documented as boost modes, but they are fully accessible on the dial.

The Maxi uses a power level scale from +4, *, +3, *, +2, *, +1, *, 0, down to -4. There is a hidden boost mode accessed by pressing the center button while at +4. It's active for just 5 shots.

The Atom keeps it simple with clearly demarked power levels from Full down to 1/32. Additional, even lower power levels of 1/64 to 1/1024 are available under a low-power mode accessible via the Mode button.

Findings: The Retra Maxi is brighter at Max Boost mode compared to the HF-1. The HF-1 +2 level is a bit lower than Maxi +4 level.

Backscatter advertises that the Atom at Full is equivalent to the HF-1 at Full. I found that it is somewhat dimmer than the HF-1 at Full.

Summary Notes:

Range – 1.5 meters (4.9 ft), F16, ISO64 - values are Photoshop brightness %, delta vs. Maxi Boost

NOTE: I added this 1.5 range meter setup as the measured values in the 65cm setup didn’t clearly show the real-world differences in brightness. This table shows more distinctly that the Maxi has more power at the high end than the HF-1 or Atom.

Range of 65cm (25 inches) from the wall

Summary Notes:

(10 frames at 3 frames per second)

Summary Notes:

Full Power

Half Power

Quarter Power

Eighth Power