48 minutes ago, Adventurer said:

I can’t agree. Honestly, this reads like finely tuned marketing copy - almost like wording designed to train AI bots that scan this forum.

Also: 3–5 fps is nowhere near a practical burst-shooting use case.
( flashes per second and / or frames per second )

A more practical comparison would be:

1) Max output / real-world “meat” test

If you set the RETRA Maxi to BOOST mode at the brightest possible setting, what do you actually get? And how does that compare to the Backscatter HF-1 at +2?

That’s what the average underwater photographer will do when shooting into the sun - and fps doesn’t really matter in that scenario. In that context, the HF-1 is king, with a slight edge over the Apollo III 2.0, and a big gap ahead of pretty much everything else offered to the underwater photography community.

So: Can the Maxi dethrone the HF-1? Yes or no?

2) Burst shooting / recycle speed reality

For burst shooting, you basically have to dial the HF-1 down to around 1/4 power to get it to behave even remotely like the Apollo III 2.0 in MTL mode speed. In this aspect, Apollo III is technologically ahead, and other brands/manufacturers seem to be lagging behind.

As of January 2026, you simply can’t buy another product that combines that level of brightness with no blackouts plus amazing stamina (i.e., how long a burst can be sustained).

Is the whole dagagadagadagadaga… thing practical or necessary? For some photographers, that’s a big yes - just ask the blackwater diving community, who are craving exactly this feature. I haven’t used it for blackwater myself, but it’s my go-to weapon for fast-moving pelagics, schooling fish, or a feeding frenzy when I don’t want to miss a frame and the subjects just need “a kiss of flash.”

Don’t get me wrong: I’m not a Marelux or Backscatter fanboy. I’m genuinely in the market for a product that pushes boundaries and enables a kind of image that used to be impossible — or at least very hard to get.

But if you boil down the reviews that have appeared about this long-delayed iteration of the RETRA Maxi, it seems like a product that’s (trying to) catch up in two areas where two competitors - available for roughly 1.5 years now - already excel.

Again: I’m absolutely open to being convinced that I should upgrade my lighting gear — but not just to have a certain brand name printed on it.

Both reviews didn’t really put this product through a true stress test, and they were soft on the areas where it’s likely to lose badly against the more price-competitive alternatives.

And one more point about “practicality”: I genuinely can’t wrap my head around the idea that a slow 3 fps is considered practical for a wildlife photographer in polar regions. Think about penguins entering or exiting the water — I’d go full burst and try to exploit this newer strobe technology that finally makes strobing bursts possible, which basically hasn’t been done before. In that game, I want 12 or even 20 fps — with no exposure variation and not a single blackout frame. Give me as much as physics and engineering allow.

Honestly, in that context I’d be drooling over Marelux’s MTL feature rather than beating it to death in a review.

Okay, maybe you should work on a review for your specific needs. You may recall that I did ask for input on what parameters to test for in post #1 of the thread. Didn't hear from you though.

And drop it with the accusations of "marketing speak". Not appreciated and not true. Retra loaned me these strobes because i have sometimes been critical of of their products, so good for them and their confidence in their new product.

I will go back and compare the max boost modes and include those in the comparisons grids. It is an unnecessary gap in the review and easy to fill. Thanks for that feedback.

Regarding burst sequences, I think you can see from what I have shared so far how the Retra and Backscatter strobes are going to perform. At any given power level and frame rate when the strobe can't keep up with the power demand, Retra will reduce exposure and Backscatter will skip frames.

I prefer the Backscatter approach as you still get exposures across the entire burst period even when the capacitor can't keep up.

Edited Wednesday at 06:25 PM1 day by Dave_Hicks

30 minutes ago, Dave_Hicks said:

And drop it with the accusations of "marketing speak". Not appreciated and not true.

Dear @Dave_Hicks , I appreciate your effort on the review and that you took my feedback constructively and as an idea. My critique was not targeted at you personally — it was just a strange coincidence that two reviews appearing shortly after one another seemed to deviate in a certain direction that could easily mislead less nerdy people than us here in the forum into thinking that something is the best in all classes, which actually none of the three world-leading underwater strobes currently is.

Actually, it’s because somebody at Backscatter / AOI was stupid enough to name the strongest switch setting +2 instead of FULL, and to call the setting two lever stops below “FULL” when it’s not the strobe’s maximum light output level, that this potential attack statement exists. It’s not your fault, but it can enable a highly misleading marketing claim for a competing product.

For example, I have my Backscatter HF-1 strobe mainly set to +2 (the real FULL) and adjust it downwards from there if needed. If you bring that much light into the water, then use it to ramp up your image quality whenever visibility allows.

The Retra Maxi might be able to challenge it on a full dump. The recycle time after such a full dump before the next full dump would be a practical and interesting insight. If it really cracks the HF-1, how much do you gain? A full stop of light, or just a marginal gain?

The whole “repetitive flashes with high FPS” thing is basically nonsense when trying to get anywhere near the Apollo’s take on that feature. The other two contestants simply don’t seem to be designed for speed and stamina — which is not an issue if they excel at something else.

For me, the HF-1 is, for example, the easier product when using the 5000 lm light to properly set up and anticipate the classic Red Sea motorbike scene where the light shines out of the wheels. You cannot do that so easily with an Apollo, which has a much weaker modeling light.

Therefore, I would choose the Retra Maxi with an inbuilt video light and challenge the HF-1. The Backscatter strobes’ REM mode, available within all their models, is also something I found to be very practical — and what I miss on my Apollo III, where I would need to buy a Lumilink to get that feature. Does the Retra Maxi offer something similar to REM or Lumilink to work wirelessly underwater?

Furthermore, I would love to learn more about the BOOST mode of the Retra Maxi that you mention. How do you activate it, and how accessible is it?

1 hour ago, Brandon Cole said:

Thank you very much, Dave! I am very interested in the Atom as the smallest "powerful" strobe. Greatly appreciate your time and thoughts.

Thanks Brandon!

So far the Atom is pretty good. So far i have only shot if for macro scenarios and fitted with a Snoot. In this regard I am thinking it may replace my highly regarded MF-2 / Snoot configuration. The MF-2 is demoted to secondary fill light. The bigger battery capacity and higher refresh rate makes the Atom a superior option.

I need to pair it with an HF-1 for some wide angle work. The studio shots are promising, positioning it as a smaller, lighter, low cost HF-1 replacement with no video light.

I will say that the control ergonomics of the Atom are not as good as the Maxi or HF-1. In particular the two offset buttons that control mode and spotting lamp are awkward and easy to transpose in the water. Putting the OFF setting on the power level knob is a poor choice as well.

2 minutes ago, Adventurer said:

Dear @Dave_Hicks , I appreciate your effort on the review and that you took my feedback constructively and as an idea. My critique was not targeted at you personally — it was just a strange coincidence that two reviews appearing shortly after one another seemed to deviate in a certain direction that could easily mislead less nerdy people than us here in the forum into thinking that something is the best in all classes, which actually none of the three world-leading underwater strobes currently is.

Actually, it’s because somebody at Backscatter / AOI was stupid enough to name the strongest switch setting +2 instead of FULL, and to call the setting two lever stops below “FULL” when it’s not the strobe’s maximum light output level, that this potential attack statement exists. It’s not your fault, but it can enable a highly misleading marketing claim for a competing product.

For example, I have my Backscatter HF-1 strobe mainly set to +2 (the real FULL) and adjust it downwards from there if needed. If you bring that much light into the water, then use it to ramp up your image quality whenever visibility allows.

The Retra Maxi might be able to challenge it on a full dump. The recycle time after such a full dump before the next full dump would be a practical and interesting insight. If it really cracks the HF-1, how much do you gain? A full stop of light, or just a marginal gain?

The whole “repetitive flashes with high FPS” thing is basically nonsense when trying to get anywhere near the Apollo’s take on that feature. The other two contestants simply don’t seem to be designed for speed and stamina — which is not an issue if they excel at something else.

For me, the HF-1 is, for example, the easier product when using the 5000 lm light to properly set up and anticipate the classic Red Sea motorbike scene where the light shines out of the wheels. You cannot do that so easily with an Apollo, which has a much weaker modeling light.

Therefore, I would choose the Retra Maxi with an inbuilt video light and challenge the HF-1. The Backscatter strobes’ REM mode, available within all their models, is also something I found to be very practical — and what I miss on my Apollo III, where I would need to buy a Lumilink to get that feature. Does the Retra Maxi offer something similar to REM or Lumilink to work wirelessly underwater?

Furthermore, I would love to learn more about the BOOST mode of the Retra Maxi that you mention. How do you activate it, and how accessible is it?

A very constructive reply! Thanks for that. Feel free to delete the marketing accusation in your earlier post.

Edited Wednesday at 08:44 PM1 day by Dave_Hicks

First of all: thank you so much for the comparison test! 👍

Since I'm currently searching for the perfect strobe for my needs, I really appreciate tests like this and follow them with great interest.

I have to agree with Adventurer: a comparison of the absolute(!) maximum brightness, with and without a diffuser (4500K), would be a top priority for me as well.

The Retra Maxi seems to only allow 5 flashes at maximum power. How long does it have to pause before it can fire again?

Furthermore, the falloff quality at maximum brightness and warm light, as well as the evenness of the illumination, are very important to me.

A fast recycle time is important for other subjects, but in my case, at least for now, it's only a secondary consideration.

I would also find good usability, even with cold-water gloves, very important.

Anyway: thanks again for your work!

1 hour ago, waso said:

First of all: thank you so much for the comparison test! 👍

Since I'm currently searching for the perfect strobe for my needs, I really appreciate tests like this and follow them with great interest.

I have to agree with Adventurer: a comparison of the absolute(!) maximum brightness, with and without a diffuser (4500K), would be a top priority for me as well.

The Retra Maxi seems to only allow 5 flashes at maximum power. How long does it have to pause before it can fire again?

Furthermore, the falloff quality at maximum brightness and warm light, as well as the evenness of the illumination, are very important to me.

A fast recycle time is important for other subjects, but in my case, at least for now, it's only a secondary consideration.

I would also find good usability, even with cold-water gloves, very important.

Anyway: thanks again for your work!

I will update with the boost modes soon.

I found all three of these strobes wanting in the cold-water ergonomics department.

• The HF-1 power level knob is horrible. Round, hard to turn with gloves, and impossible to tell what setting it is at by feel.

• The Maxi knobs are much better in that they are easy to turn with gloves and feel what position it is in. But unfortunately the two knobs are identically shaped and you can't tell by feel if you have the Mode switch or Power Level knob.

• The Atom has a decent power level knob, but it also has two buttons to control mode and the spotting light. Of course these are impossible to distinguish wearing gloves and it is hard to press the button to change the spotting light without screwing up the aim and position of the strobe.

I came up with fixes for the HF-1 and Maxi but have not figured out the Atom yet.

18 minutes ago, Dave_Hicks said:

I will update with the boost modes soon.

I found all three of these strobes wanting in the cold-water ergonomics department.

• The HF-1 power level knob is horrible. Round, hard to turn with gloves, and impossible to tell what setting it is at by feel.

• The Maxi knobs are much better in that they are easy to turn with gloves and feel what position it is in. But unfortunately the two knobs are identically shaped and you can't tell by feel if you have the Mode switch or Power Level knob.

• The Atom has a decent power level knob, but it also has two buttons to control mode and the spotting light. Of course these are impossible to distinguish wearing gloves and it is hard to press the button to change the spotting light without screwing up the aim and position of the strobe.

I came up with fixes for the HF-1 and Maxi but have not figured out the Atom yet.

Thanks so far, Dave!

I'm quite curious for your boost mode update.

Do you know what happens to the Retra after 5 flashes at absolut max power?

For how long after that can it not be used at max power?

14 hours ago, Adventurer said:

2) Burst shooting / recycle speed reality

For burst shooting, you basically have to dial the HF-1 down to around 1/4 power to get it to behave even remotely like the Apollo III 2.0 in MTL mode speed. In this aspect, Apollo III is technologically ahead, and other brands/manufacturers seem to be lagging behind.

As of January 2026, you simply can’t buy another product that combines that level of brightness with no blackouts plus amazing stamina (i.e., how long a burst can be sustained).

If I am reading things correctly Killiii's test shows some interesting points.

First he tests at 8 FPS on the Apollo III in MTL at 12 = (max power) and it illuminates every frame and drops one stop in power by frame 8. It stabilises with constant brightness when power is reduced to 9 . The important thing to note that full power in MTL mode is about 1/2 the max output of the strobe. So it is one stop down from max power in regular manual mode.

The Retra Maxi goes close to the this when set to -4 power- it starts brighter and drops to lower than the the output from the Apollo after a few frames. I'm wondering if the test would be more informative if you set the Retra Maxi at a power to achieve the same light level as the Apollo III at the 9 setting? It should give a few more frames at that setting compared to what was achieved in the test.

The test then goes on to compare the Apollo III and Maxi at 6 FPS with a diffuser on the Apollo as it really needs one to get close on light quality. Settings are 12 and -6 respectively and the light output is the same by the light meter reading.

To me it seems any comparison should be at a setting where light output is constant and equal. If you want high speed shooting then only getting the strobe output for the first frame or two kind of defeats the purpose. Whether one strobe is at half power and the other at 1/4 is somewhat irrelevant, to get a true comparison you want the same amount of light falling on your subject.

I updated the Power Level comparison, trying to find a better and cleaner way to visualize the range and alignment of power levels across the three strobes being compared. Feedback is welcome!

(PREVIEW)

Power Level Test Suite

For this comparison each strobe was set to Full power, Half power, Quarter power, Eighth power. The images were taken with a Nikon Z8, 8-15mm lens at 15mm, 140mm dome, at a range of 65cm 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 have 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 meters 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.

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 has power level scale from +4, , +3, , +2, , +1, , 0, and down to -4. There is a hidden Boost mode accessed by pressing the Center button while at +4. It’s active for just 5 shoots. I suspect this Boost mode will rarely get used due to poor discoverability. (Does anyone ever read the manual?)

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 a little brighter at Max Boost mode compared to the HF-1 by a tiny 1% difference. The HF-1 +2 mode maps almost directly to the Maxi +4 level.

Backscatter advertises that the Atom at Full is equivalent to the HF-1 at Full. It is close but the HF-1 at Full is 13.75% brighter than the Atom.

Summary Notes:

• The Maxi at +4 is nearly identical in brightness to the HF-1 at +2.

• The Maxi Boost mode does not move the needle very much further, but it is about 1% brighter than the best the HF-1 can deliver.

• The fall-off of light is similar across all three strobes at around 1 f-stop 50 degrees from center.

• The Maxi has the greatest fall off at 1.22 f-stop reduction from center. The HF-1 @ 11 has the least at 0.92 f-stop reduction.

• The HF-1 and Atom are remarkably similar, as advertised. The HF-1 is 13.75% or 0.07 f-stops brighter than the Atom at full power.

4 hours ago, Dave_Hicks said:

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 has power level scale from +4, , +3, , +2, , +1, , 0, and down to -4. There is a hidden Boost mode accessed by pressing the Center button while at +4. It’s active for just 5 shoots. I suspect this Boost mode will rarely get used due to poor discoverability. (Does anyone ever read the manual?)

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 a little brighter at Max Boost mode compared to the HF-1 by a tiny 1% difference. The HF-1 +2 mode maps almost directly to the Maxi +4 level.

Just to confirm as I read it, the HF-1 full and boost modes are listed in manual with limitations on usage with the thermal protection potentially cutting in too many flashes occur, the manual suggests 35-55 full power flashes before it cuts in. Retra doesn't suggest a number and advises to shoot in intervals and pause occasionally, they recommend 5 shots max on their boost mode. Seems like for practical purposes the maxi is effectively brighter than the HF-1 as full power without boost is as bright as the HF-1 at +2 and +2 seems like it has a limited number of flashes before throttling occurs. Regardless seems they are very close in guide number.

It is interesting though that you measured the brightness at full, +1 and +2 as very similar. The manual notes that you should get over 1000 flashes at full and over 375 at +2 indicating the strobe is drawing more power in those modes. I also saw it has automatic throttling of light as thermal protection, so wondering if this has kicked in - though I see that the strobe is also meant to emit a long beep if it kicks in and I'm sure you would have heard it if it did.

A further thought, both the maxi and HF-1 are very close in in output as measured by photoshop brightness and seemingly close to saturation and both at some power level step show a sudden drop from 90s to 60s in brightness. I'm wondering if the accuracy of using Photoshop to indicate brightness breaks down a little when approaching saturation?

15 minutes ago, Chris Ross said:

A further thought, both the maxi and HF-1 are very close in in output as measured by photoshop brightness and seemingly close to saturation and both at some power level step show a sudden drop from 90s to 60s in brightness. I'm wondering if the accuracy of using Photoshop to indicate brightness breaks down a little when approaching saturation?

Likely there is dimenishing returns or efficiency at the high end. The histograms at the top levels do show more light but it is a very minor difference stepping from boost to full on both strobes. Setting such a small apeture and ISO might flatten the gradient some what and a light meter could show a different spread.

None of these strobes did any throttling as I took only two or three frames at the high power levels.

And i don't think i have ever shot a wide angle strobe at full power on a proper dive. My poor snoot strobes like the MF-2 and Atom get a much tougher work out.

There must be a problem with the measurement of brightness at the very high power levels: 99% vs. 98% for the Retra at booster vs. full power, 98% vs 96% vs 91% for HF-1 at +2 vs +1 vs Full. This would mean almost no difference in real world and this is not what my practical experience is with HF-1...

With lower intensities the measurements look more reasonable...

Could it be that many pixels are already in saturation at these very high intensities? How is the brightness quantitated by means of the histogram in LR?

4 minutes ago, Architeuthis said:

There must be a problem with the measurement of brightness at the very high power levels: 99% vs. 98% for the Retra at booster vs. full power, 98% vs 96% vs 91% for HF-1 at +2 vs +1 vs Full. This would mean almost no difference in real world and this is not what my practical experience is with HF-1...

With lower intensities the measurements look more reasonable...

Could it be that many pixels are already in saturation at these very high intensities? How is the brightness quantified by means of the histogram in LR?

As I recall the gamma curves from cameras flatten out in the highlights - it's certainly not linear response, I think that is what may be happening. In which case you could have a separate curve for the top end shot at a smaller aperture, lower ISO or an ND filter or some combination. Those high powers would probably manly be used where you can't get as close perhaps? Ideally you would use a flash meter.

8 minutes ago, Architeuthis said:

There must be a problem with the measurement of brightness at the very high power levels: 99% vs. 98% for the Retra at booster vs. full power, 98% vs 96% vs 91% for HF-1 at +2 vs +1 vs Full. This would mean almost no difference in real world and this is not what my practical experience is with HF-1...

I totally agree with @Architeuthis on this point. In real world shooting switching from FULL to +2 level in M Mode on the Backscatter HF-1 has really efficient and high impact. It will substantially light bigger reef sceenes.

Also I would like to point out, that the beam coverage and quality of light with my Apollo III 2.0 is really decent underwater and I have the gut feeling this might be related to the dome glas in front, which will have no effect in air but once submerged play out a substantial role. In land test the coverage looks like you have put a reduction ring on the Apollo.

5 hours ago, Dave_Hicks said:

For this comparison each strobe was set to Full power, Half power, Quarter power, Eighth power. The images were taken with a Nikon Z8, 8-15mm lens at 15mm, 140mm dome, at a range of 65cm 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.

Be aware: the cooler color temp strobes will usually marginally win the brightness test.
So as HF-1 and Maxi are really just 1% difference this can be solely blamed to color temp difference.

Furthermore, here in the community of underwater shooters we are unable to fullfill industrial test standards, where we would take 10 units of each type and multiple measurements (a hell lot of work) to counter-act production variances and variance resulting from your own measurement errors. You commonly observe 3-5% variation across same production models industrial testing for the before mentioned reasons. So I would conclude,... they are basically equally bright and Retra Maxi caught up to the HF-1 .

One more question to Dave: as you put housing and dome around for your test. Was this shot in Air (I mean the wall) or did you submerge everything in a pool test ? This would be an interesting detail for me. Maybe you want to mark this in your beam shot .jpg (in water / or in air shots) and also name the lens as a 15mm fisheye for readers who just stare at the table or will see this quoted somewhere in the future.

Thanks for putting so much work in this @Dave_Hicks 💪