Adventurer

Hi Dreifish, I think your Apollo III units where not functioning OK or your test setup was faulty in some way. I cannot confirm the way you trashed that strobe, having now shot this and the HF-1 for two years. I bought the HF-1 because of your disruptive Excel sheet back in the days. In fact my HF-1 does not deliver the power you claimed at high frame rates and does many blackout frames and light variation. You may want to reach out to your dealer or Marelux to get your strobes replaced.

Just want to report back that I am using the 8-15mm fisheye with Kenko 1.4x and 2.0x TC on a Canon, unable to take advantage of the Sony 2.0x TC…. but… … recently I got myself the comlite EF RF and modified it to host the Canon RF 1.4x TC. I am really curious to try this and consider buying also the RF 2.0x TC to upgrade my IQ by a small fraction.

I think this supports also the 5% measurement and test + item variation delta I previously pointed out. Also a fresh from the factory strobe will be brighter than one that already has fired a few hundred shots. So no need in beating a dead horse and over-doing and over-interpreting these land tests. What would be interesting though is a beam (1-1.5m) wall test submerged in water to see the different dome and reflector designs come into play.

If you intend to pursue that road and cannot get your hands on a cheap 2nd hand ZEN dome from the example above, I suggest everyone to take a look at INONs very affordable small glas dome. You will need to get an adapter made, if you do not shoot their INON X-2 housing. *the sunshade is removable

oK - specs are out… 15 cm MFD look promising. Canon RF sensor to flange = 20 mm Canon RF 7-14 lens length = 109 mm I = 20 mm + 109 mm = 129 mm MFD = 150 mm MFD - I = 21 mm Focuses 2,1 cm in front of front glas. But if the 190 degree FOV at 7mm focal length is not a typo it will create lots of headaches with port positioning.

Even more interesting would be the option to use the RF2.0x TC 🤩 let‘s wait and pray that the technical data will serve us underwater photographers! There is still the minimal chance that Canon totally screws this up with a humongous minimum focusing distance (MFD) which would render it useless for underwater photography.

Hi all, does anybody know the author / anchorman of these four videos ? At first I thought he is affiliated with the former British camera store OceanOptics, because of the channel name. That however seems wrong. The channel origin seems to come from The Netherlands and I think that this might be confirmed by a slight Dutch accent I am hearing. I am interested to learn more about his uw photographic works and if he maybe is a well established pro or even a waterpixeler 😉 ?

If it is coming at an ultra humongous price, I am afraid. It will be interesting (but also a very slim chance) if we can combine it with RF1.4x and RF2.0x teleconverters. Let‘s also pray that Canon will keep the MFD ultra low and the entrance pupil in the front as on our beloved EF 8-15 fisheye.

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 💪

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.

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?

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.

Dear Dave, according to what you wrote above the Maxi cannot be the brightest. If the delta at +1 gap is that close, than it is very logic that the Backscatter HF-1 Hybrid Flash will outperform the Retra Maxi Strobe when set at +2 Level. Could you please clarify why the HF-1 was not put at +2 power level when you compared it ?

Michi, if I read Dave & Killiii correctly than the Maxi is not what you are looking for and simply unable to deliver at these fps. The Backscatter HF-1 is able to do it (I own and tested this) but there is brightness variation and quite a few blackout frames every few cycles in burst shooting. The only strobe which is currently doing what you are looking for and which delivers zero light variations and zero blackout frames at high burst for more than 100 frames is the MARELUX Apollo III 2.0 in MTL Mode - which I also happen to own. I would subscribe to everything Henley Spiers wrote in his review: DivePhotoGuideFirst Impressions of the Marelux Apollo III 2.0 StrobeBoth my Backscatter HF-1 and Apollo deliver warmer light than my friends Seacam and old Retra, with a very simple fix I received from Hydronalin, Germany.

Actually that’s no longer true! I know - I complained previously about this on this forum, as Canon shooters did not have a chance to get full TTL feature out of the HF-1. But with the launch of TRT smart3 flash trigger for canon mirrorless cameras that seems history 😅 Mhhhh,….. 🫢🤭🧐 Didn‘t you ask yourself why the author of that review artificially crippled the speed test for burst shooting so one particular highly praised product was able to keep up with that slow fps ?