5 hours ago, Adventurer said:

Hi @Kiliii Yuyan

- “Retra the best… f*** the rest?” 😄

Seriously though: what did the poor Apollo III ever do to you to get roasted that hard?

Jokes aside, I’m trying to reconcile your January 2026 conclusions with a couple of practical, quantitative questions:

1. Apollo version / light quality

   Your post is Jan 2026 and you sourced the latest Retra Maxi — why not bench-test the current Apollo III revision as well (the one with the micro-peened dome glas update that’s supposed to improve beam/“quality of light” and reduce the need for the dome diffuser)?

   If it simply wasn’t available: totally fair - but then the “needs diffuser / poor coverage” verdict is basically “Apollo III 2.0 as tested”, not necessarily “Apollo III today”, right?

2. Missing HF-1 = missing power anchor

   No HF-1 in the lineup means there’s no obvious power/price reference point. Alex Mustard has called the Backscatter HF-1 „the strongest strobe he’s tried“ — was it just impossible to get one in time, or was there a reason you skipped it?

3. Retra Maxi burst: what’s the real ceiling without drama?

   8 fps is a fine level playing field, but what I (and probably many) want is the Maxi’s actual max sustainable rate with no black frames and no meaningful exposure drift, plus the GN/power level where that holds.

   So in practical terms: does the Maxi get anywhere near Apollo’s 10–12 fps-ish territory in its stable modes, or is it fundamentally behind on high-fps burst consistency?

Context: I already own HF-1 (brightest) + Apollo III 2.0 (fastest). I’m trying to figure out whether the Maxi adds a new capability or mostly overlaps.

Thanks in advance — genuinely curious, and I appreciate the effort you put into measuring this stuff.

PS: I’m not allergic to Retra winning - I just want any comparison to include the actual monsters in the room.

I have the HF-1 and the Atom and will make those comparisons. Thanks for sharing your ideas for evaluating these similar strobes.

6 hours ago, Muellema said:

Hi Dave,

would you share the 3D/CAD files of the knobs. I also sometimes mix up the power and mode knob due to almost same design (only length is differnt). I was thinking to design a clip-on knop. But if your design solves also the "salt problem"👍😃. To be honest, I hadn't figured out the salt problem until today. Will later remove a knop on my strobe to get an idea how much salt stuck there.

Br Markus

I share all of my designs and will post the Retra knobs soon. I am going to complete the set with a Power Level knob and will share them after a few more test dives.

Can anyone share the height and diameter of the Pro Max knobs? I want to know if they are the same. Some of the older Retra models have smaller knobs.

@Kiliii Yuyan well done sir!

15 hours ago, Adventurer said:

Hi @Kiliii Yuyan

- “Retra the best… f*** the rest?” 😄

Seriously though: what did the poor Apollo III ever do to you to get roasted that hard?

Jokes aside, I’m trying to reconcile your January 2026 conclusions with a couple of practical, quantitative questions:

1. Apollo version / light quality

   Your post is Jan 2026 and you sourced the latest Retra Maxi — why not bench-test the current Apollo III revision as well (the one with the micro-peened dome glas update that’s supposed to improve beam/“quality of light” and reduce the need for the dome diffuser)?

   If it simply wasn’t available: totally fair - but then the “needs diffuser / poor coverage” verdict is basically “Apollo III 2.0 as tested”, not necessarily “Apollo III today”, right?

2. Missing HF-1 = missing power anchor

   No HF-1 in the lineup means there’s no obvious power/price reference point. Alex Mustard has called the Backscatter HF-1 „the strongest strobe he’s tried“ — was it just impossible to get one in time, or was there a reason you skipped it?

3. Retra Maxi burst: what’s the real ceiling without drama?

   8 fps is a fine level playing field, but what I (and probably many) want is the Maxi’s actual max sustainable rate with no black frames and no meaningful exposure drift, plus the GN/power level where that holds.

   So in practical terms: does the Maxi get anywhere near Apollo’s 10–12 fps-ish territory in its stable modes, or is it fundamentally behind on high-fps burst consistency?

Context: I already own HF-1 (brightest) + Apollo III 2.0 (fastest). I’m trying to figure out whether the Maxi adds a new capability or mostly overlaps.

Thanks in advance — genuinely curious, and I appreciate the effort you put into measuring this stuff.

PS: I’m not allergic to Retra winning - I just want any comparison to include the actual monsters in the room.

To be fair, if you read the post Kiliii notes that he didn't have the strobes you mention available to test. Sure it would be nice to include them if available, but Kiliii is doing the testing and using his time to provide you with test data free of charge. You can only make judgements on the equipment you actually test so of course the comments apply to the strobes as tested. So you are saying there are two versions of the Apollo III 2.0? Or is the strobe tested the Apollo III and the new version Apollo III 2.0? It's not immediately obvious if not familiar with the product line.

Hi everyone, I see there's been quite a bit of activity while I was away being horrified by the news...

@Dave_Hicks Thank you for the Retra knob issue, I often am annoyed by the knob designs, especially when power level and mode knobs are not enormously different. I too, shoot with strobes way out as a backlight and often find myself flipping the wrong knob. I guess we share the same dyslexia that way. If you have any desire to do the same more controlled testing with the Backscatter strobes, happy to share the Photoshop scripts!

@Architeuthis

I did indeed include the Retra Pro Max II, their latest high-end pro strobe. For some reason I wrote Pro Max 2 throughout but my brain can't keep track of how manufacturers write their numbers. mk2, mkII, v2, 2, TWO, II...

@Adventurer

1. The Apollo III 2.0 strobes are what I tested. They are the glass-domed ones, that came to me in early November 2025. I presume they are the very latest, although I did receive two slightly different versions, with minor different knob designs and other differences in packaging. Both designs however seemed to be the same as far as performance. They are quite pretty too.

2. I had to buy all the strobes I tested, so alas, no way to test the Backscatter unless someone wants to give me some. Seems like a pretty reasonable trade.

3. I would be happy to test the Retra Maxi and Apollo at higher frame rates, but the testing took A LOT of time, 2 full workdays with writing the scripts and all of that. I might find the time to do more testing but my personal curiosity is satisfied -for now- and I learned a lot.

@Chris Ross Thx mate.

Matthew and I have both been shooting the Retra Maxis here in Grand Cayman. We will talk about them on our show after the trip. Here are a few photos taken with them that I have processed out (for other reasons) so I can share easily.

h

Thanks Alex for the real-life images, the one thing I do notice is that in blue water, the Maxi's color temperature seems to make everything just that bit bluer and more crispy, which is not my favorite thing (tastes will vary one this a lot). The warming diffusers would seem to be important to me.

I also updated my strobe test review, after some great (minor) feedback from Oskar at Retra on testing methodology. I re-analyzed the the light quality of the strobes and the Pro Max II and Seacam you can now see are slightly better in falloff, although both Retras and the Seacam are quite close. The Apollo falls well behind.

Details here:

https://blog.kiliii.com/underwater-strobe-shootout-marelux-apollo-iii-2-0-retra-maxi-seacam-160d-retra-pro-ii/

Edited Sunday at 06:27 PM2 days by Kiliii Yuyan

30 minutes ago, Kiliii Yuyan said:

Thanks Alex for the real-life images, the one thing I do notice is that in blue water, the Maxi's color temperature seems to make everything just that bit bluer and more crispy, which is not my favorite thing (tastes will vary one this a lot). The warming diffusers would seem to be important to me.

I think you misunderstood the effect of warm flashes. With warm flashes, the foreground is colored by the warm lights, making it necessary to correct the white balance of the whole pic a little bit to the blue - which renders the background which is out of the reach of the flash more blueish. The warmer the flash, the more blue the water becomes in wide angle photography.

Just now, Jens H said:

I think you misunderstood the effect of warm flashes. With warm flashes, the foreground is colored by the warm lights, making it necessary to correct the white balance of the whole pic a little bit to the blue - which renders the background which is out of the reach of the flash more blueish. The warmer the flash, the more blue the water becomes in wide angle photography.

I do understand how the relative shift of color temperature underwater works. What I am saying, though, is that despite that, what I can see is that the strobe light has a quality that is more penetrating, which appears to give more contrast and clarity, and overpowers the ambient a bit more. I don't know why this is the case- other people have mentioned this before as well. It may well be cognitive bias, it could be the visibility.

If I am correct, however, I would guess the effect is due to the fact that that the wavelengths of blue light travel further underwater than warmer wavelengths (water absorbs wavelengths increasingly towards red)- in both directions to and from the subject.

While you can adjust the global warmth of an image in Lightroom, say, you can't adjust the color temperature differences coming from the same light source hitting different parts of the subject. There are probably other subtle effects going on as well, such as the scattering of different color wavelengths and the interference with existing light.

One other possibility is simpler- perhaps the camera or Lightroom's automatic white balance adjustment treats the scene differently depending on the color temperature of the strobe, and does not compensate as much towards warmth. The algorithms I assume are complex and probably not just trying to neutralize the subject's color temperature.

Edited Sunday at 06:54 PM2 days by Kiliii Yuyan

The Maxis have been thoroughly enjoying thus far for both macro and wide angle. The Pro maxes have an edge in light quality, especially without diffusers, but i have zero complaints about maxi quality of light and the power and speed are hugely enjoyable

Edited Sunday at 06:56 PM2 days by MatthewSullivan

@Dave_Hicks Just measured the Retra Pro Max II knobs, the mode dial is 18.8mm at the base diameter, 25.5mm high. Power dial is also 18.8mm at base diameter, 33.5mm high.

Custom Retra Power Level and Mode Knobs

5 minutes ago, Kiliii Yuyan said:

@Dave_Hicks Just measured the Retra Pro Max II knobs, the mode dial is 18.8mm at the base diameter, 25.5mm high. Power dial is also 18.8mm at base diameter, 33.5mm high.

Oskar says they are not removable on the Pro strobes. But I will bring you a set of Maxi knobs if you still plan on diving Three Tree in a couple of hours.

Oh hell yes, that would be amazing. I owe ya one. See you there! I'll be diving my new and improved EMWL setup so there may be some hallelujahs or some cursing. Or both.

I've been diving with the Maxi's for a few weeks now and taken them on about a dozen dives with a mixture of Wide and Macro experiences. They have been performing like champs with great reliability, performance, and battery life.

More Maxi Cold Water Sample Images:

Edited Sunday at 08:10 PM2 days by Dave_Hicks

On 1/9/2026 at 2:03 PM, Michi said:

I just need very fast recyce times but never more strobe fire than for around 10/15 shots…

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:

DivePhotoGuide

First Impressions of the Marelux Apollo III 2.0 Strobe

Both 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.

Continuation of the Pre-Review of the Retra Maxi Strobe....

Studio Comparison Shots with Retra Maxi, Backscatter HF-1, and Atom Strobes

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

These specs include:

• High power, Wide Angle capable

• Lithium Ion powered, two cells per strobe

• Rapid recycling times

• $800-1300 USD price range

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.

Unfortunately, it’s not an exact apples-to-apples comparison. The Retra does not have precise gradations at these power levels. It uses a 17-level scale from -4 to +4 “units” in .5-unit increments. The units don’t equate to F-stops exactly, but Retra reports the +3 and +2 are close to Half and Quarter power, so I went with that approximation.

The HF-1 does have a Full setting with Half, Quarter, and Eighth levels, but it also has two higher “Boost Levels” beyond F on the power dial. I found that the “F+1” or “11” setting was very close to the Retra Maxi at Full Power.

The Maxi also has single 30% boost level, but it is hidden behind a 3 second press of a button and then active for exactly 5 shots. I suspect this 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 1/32 to Full. Additional even lower power levels of 1/64 to 1/1024 are available under a Low Power Mode accessible via the Mode button.

 

Power Level Test Suite

Findings: The Retra Maxi is a little brighter at each level. Partially this is due to the variance of the power level scales. One-click higher on the HF-1 evens it up with the Maxi. Since this HF-1 has those two additional clicks beyond Full, this is easily achieved.  I included an extra comparison row with the HF-1 turned to 11. (Full power plus one more click)

Backscatter advertises that the Atom at Full is equivalent to the HF-1 at Full, and the comparison shots support this claim. The HF-1 does have it’s +1 & +2 modes, so there is more headroom on the bigger strobe vs the Atom.

The Maxi is the brightest at Full, but I don’t think anyone is going to be lacking power with any of these strobes.

Summary Notes:

• The HF-1 at Full +1 click is very similar to the Maxi, just a .03 f-stop delta.

• 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 0.07 f-stops brighter than the Atom at full power.

Edited 15 minutes ago15 min by Dave_Hicks
Fixed bullet list formatting

Coverage at Common Power Levels (Diffuser 4500k)

 

Summary Notes:

• All three of these strobes are probably best configured with a warming filter due to their very cold outputs of 6400-6500 kelvin.

• The diffuser for the Retra Maxi is their Wide-Angle Dome Diffuser delivering a 4500K output. Retra does not offer a flat diffuser.

• The Backscatter HF-1 and Atom strobes were tested with their respective 4500K flat diffusers.

• The fall off in power from Full was around 0.50 f-stops for all three strobes.

• The Atom had the least reduction at 0.40 f-stops, and the HF-1 had the most at 0.50 f-stops.

Edited 11 minutes ago11 min by Dave_Hicks

Burst Shooting Results at Common Power Levels

(10 frames at 3 frames per second)

 

Summary Notes:

• The Retra Maxi clearly has a design priority of delivering a flash with every frame shot, even if that flash is severely under powered.

• The Backscatter HF-1 and Atom have a different design priority where they attempt to flash only if they are close to the requested power level, resulting in black frames while the capacitor recharges.

• Both designs have their own valid logic, and reasonable photographer might prefer one over the other.

• The Retra Maxi will only deliver properly exposed frames at the start of the burst using Full or Half power. Subsequent shots will be very underexposed and may not be usable.

• The Retra Maxi delivered just 1 fully exposed frame in a 10-shot burst at Full Power.

• The Backscatter HF-1 delivered 5 fully exposed frames across the full span of the 10-shot burst at Full Power.

• The Backscatter Atom delivered 3 fully exposed frames across the full span of the 10-shot burst at Full Power.

• At Half Power the Maxi and HF-1 both delivered usable exposures across 10 shots, with the HF-1 being more consistent.

• At Quarter Power all three strobes delivered the expected exposures across the full 10 shot burst.

• Realistically, one should probably consider Half Power to be the ceiling for taking Burst Mode images with any of these strobes.

Edited 12 minutes ago12 min by Dave_Hicks

Coverage delivered with Reduction Rings

Summary Notes:

• Retra’s stock reduction ring is 88mm wide.

• The Retra 88mm reduction ring provides a more defined edge that is only slightly smaller than the naked strobe.

• Backscatter does not currently provide any reduction rings for the HF-1 and Atom strobes.

• I have made my own set of custom reduction rings for all three strobes with a consistent 78mm aperture. (Available for free on MakerWorld)

• The 78mm reduction rings provide a sharp edge with about 90-100 deg width.

• Additional 60mm and 38mm Macro & Super macro rings are available for all three strobes.

• The Retra reduction ring does not allow for the use of a warming filter.

• My custom HF-1 reduction ring fits over the 4500k flat filter allowing the use of both modifiers at once.