Strobe Review: Scubalamp D-Max and Retra Pro Flash

Retra Flash Pro:

Retra has been a household name in underwater lighting for 10 years now. While for a long time, their LSD snoot system was the poster child of the company, the release of the original Retra Flash meant a step forward for them from strobe accessory manufacturer to strobe manufacturer. In early 2020, after a series of delays, Retra then started shipping their second generation flash, which now came in two varieties: Prime and Pro. In this review, we will focus on the Pro model, as it is certainly the more exciting of the two, featuring a whopping 150Ws light output on the spec sheet (the Prime is 100Ws).

Retra Flash Pro front view with circular flash tube and central LED light.

Retra Flash Pro side view (with optional neoprene sleeve).

Below are the stated specifications of the Retra Flash Pro:

The second-generation Retra Flash, both Prime and Pro, feature what according to Retra is the world’s first fully circular flash tube, as opposed to the horseshoe design most other strobes use. Compared to other strobes with circular flash tubes, like the Scubalamp D-Max, we will be comparing it to in this review, the diameter of the flash tube is fairly small compared to the diameter of the chassis.

Both second-generation models feature some truly next-generation functionality. This includes Bluetooth connectivity with the companion app. The pairing process is as painless as it could be (we used the Android version of the app) and the app offers a range of useful features like firmware updates, a readout of the trigger count, and programming of the U1 and U2 modes. Retra has already released several firmware updates through the app, which have rectified a few early issues we had noticed when first using the strobe.

Both user-programmable modes can be set to pre-flash cancellation (Smart SL), Pilot light output adjusts, a low power mode which cuts the light output by about 1 stop for all power levels, and, perhaps most excitingly, a high-speed flash sync (HSS) mode. HSS allows for shutter speeds beyond the conventional sync speed of a camera, up to 1/8000th of a second, which unlocks a range of creative possibilities for the avid underwater photographer. It should be noted though, that due to its optical-only triggering, the Retra Flash requires a special HSS flash trigger board inside the housing. These are readily available from UWTechnics and other brands, but don’t come cheap so the extra cost will need to be factored in if HSS is an important feature to you.

The flash takes four standard AA rechargeable batteries. Its capacity can be doubled with the optional “Supercharger” battery extension. I (HK) personally consider this a must-have accessory for wide-angle shooting, as the strobes are otherwise slow to recycle at high power and often won’t last a full day of diving. Thankfully the Supercharger more than halves recycle time and more than doubles the number of flashes on a single charge, but also adds significant cost.

The Retra Flash Pro/Prime-only accepts fiber-optic connections in both the standard Sea&Sea and Inon style so your previous fiber-optic cables will likely be compatible. Retra also offers an optional E-Opto converter, which makes an electrical connection and converts it to the required fiber-optic signal. This option however only works in standard manual mode (no TTL and also no HSS).

What’s inside the package

Unboxing the flash is a joy, with almost all of the packaging made from cardboard and appears sturdy enough to inspire confidence in accident-free shipping around the globe. Included in the package are the flash itself, a standard ball-mount adapter, an extra set of battery compartment o-rings, and some o-ring grease. The flash does not come with any protective covers. These are, however, available as optional accessories. The user manual can be found on the Retra app. The box also includes a post-card-sized print of one of Alex Mustard’s images taken with the original Retra Flash, though this may vary from one unit to the other.

Rear controls

Retra Flash Pro rear panel with mode dial (left), battery compartment (top), pilot light switch and status LED (centre), power dial (right) and optical sensor (bottom)

Retra Flash Pro mode dial.

Retra Flash Pro power dial.

The back of the strobe features the mode and power dials, the optical sensor, battery compartment, pilot light button, and status LED. All labels are right-side-up when the strobe is hanging from the strobe arms, which is the usual way of using them for most underwater photographers. Power can be adjusted in 13 levels in ½ stop increments (+3 to -3). They also include a simple percentage label ranging from 1 to 100. The mode dial features the following positions: OFF, BATT/TEST, ON, TTL, U1, U2, and SOS. In the BATT/TEST position, the strobe gives a color-coded representation of the current battery level in four discrete levels (100-75%, 75-50%, 50-25%, and 25-0%). In this mode, it is also possible to trigger the strobe manually at the current power level by pressing the pilot light button, a very useful feature for testing the strobe as well as for people who enjoy creating long exposure photography underwater.

Retra Flash Pro battery compartment.

The battery compartment knob is easily operated even with wet or cold fingers (which you should probably dry before opening the battery compartment) and the cap itself is sealed with a double o-ring. Battery contacts are very sturdy. As is standard with most strobes these days (interestingly NOT for the D-Max though), the battery compartment is sealed from the rest of the strobe, so a flood should not result in loss of the entire strobe. Both the Prime and Pro flashes come with a built-in leakage detector. However, this is not to be confused with a vacuum system. It’s a simple moisture alarm that alerts the user through the status LED.

Speaking of the status LED: It is fantastic. It is bright and protrudes from the chassis, which makes it very easy to see even when glanced at from the side. It changes color depending on which mode the strobe is in. In a recent firmware update Retra have added a “breathing” effect, which looks pleasing, but in my opinion, takes away a little bit of the immediacy of the status LED as it cycles through levels of intensity from off to on periodically and will therefore sometimes make you wait a moment to clearly see which color it’s displaying. It’s not a big inconvenience, but personally, I’d like this effect to be an option to switch on or off in the app. Through a firmware update they have also added an option to constantly show the battery level in any mode, which sounds quite useful but in reality, often gives battery readings that are far lower than the actual remaining charge. During the battery endurance testing, we did as part of this review the strobe showed a flashing red light, which indicates a charge below 25%, at only 50% of the number of flashes it would eventually produce. Retra’s own manual states that you should wait at least 30 seconds before switching to BATT/TEST to get an accurate reading of the remaining battery charge. This makes me somewhat question the real-life benefit of this feature, but since it remains switched off by default and has to be specifically enabled in the app this is a minor complaint.

Build quality

The flash is built superbly well. All parts give a strong impression of durability. The aluminum chassis is very sturdy and dare I say quite sexy!

The physical dimensions of the strobe are remarkable considering its powerful interiors. They are almost identical in size to my old Inon Z-240 strobes, which makes them ideal for travel and for lighting macro shots or close-focus wide-angle images. The slightly longer body makes this a little bit more difficult than with the Z-240 though, at least with a short macro port.

Reliability has been excellent so far. My two flashes have reached a trigger count of around 8000 at the time of writing this review and have not failed me since the first firmware update. In the initial firmware version, the strobe would occasionally fail to switch on properly, requiring for it to be switched off and on again to function correctly, and was very picky with older batteries. Sometimes the strobe would simply show a flashing red light and wouldn’t charge its capacitors, even though the batteries were fully charged, tested, and conditioned. This hasn’t been an issue for me since so Retra at least appears to have done a good job at improving their firmware.


At the front of the strobe, Retra uses a proprietary bayonet mounting system for accessories. All accessories for the original Retra Flash are compatible. The bayonet system works extremely well and is easy to operate and Retra offers a wide range of accessories to modify the quality of light and beam angle. The reduction ring produces a sharper beam edge and is great for eliminating backscatter in low visibility situations. The beam angle can be further reduced with the two macro rings, which can also serve as a wide-angle snoot. I have personally used two different diffusers: the standard wide-angle diffuser and the shark diffuser. While the wide-angle diffuser features a very grippy outer ring for mounting to the bayonet system, the shark diffuser appears to be of an older style and is much more finicky to attach and detach. Apparently, Retra has now updated the shark diffuser to the new design with the outer ring as well, so this should not be an issue anymore. Given the exceptional quality of light without any diffusers, I personally use mine without any accessories in most situations. Of course, Retra’s own LSD snoot is also compatible with both the Retra Flash Prime and Pro. Retra also offers some neoprene sleeves to protect the strobe. The ones are shown here apparently are not made anymore as they kept sliding off the strobe at either the front or the back (hence the zip ties). Retra instead now offers a shorter neoprene sleeve that works well when combined with the more rigid bumpers.

Front bayonet mount for accessories.

Supercharger mounted to Retra Flash Pro.

  1. Introduction
  2. Scubalamp D-Max
  3. Retra Flash Pro
  4. Underwater review and strobe comparison
  5. Comparison and Conclusion