Retra Flash

Manufacturer: Retra UWT
Type: strobe
Year introduced: 2017 (original Flash); 2020 (Prime / Pro); 2021 (Pro X / Prime X)
Founder: Oskar Zupančič (Oskar@RetraUWT on Wetpixel)
Country of origin: Slovenia
Price at launch: €699 (original Flash); €799/€899 (Prime/Pro); €899/€999 (Prime X/Pro X)

Overview

The Retra Flash is a line of underwater strobes produced by Retra Underwater Technology (Retra UWT), a Slovenian company that entered the strobe market in 2017 after establishing itself as a maker of optical snoots and accessories beginning in 2011. The original Retra Flash was a 100W/s strobe that began shipping to pre-order customers on September 22, 2017 (^[1]). A new manufacturer entering the underwater strobe market is rare, and the Flash was positioned as a direct performance upgrade over the dominant Inon Z-240 and Sea & Sea YS-D series strobes.

Retra’s defining philosophy across all generations has been an emphasis on quality of light rather than raw guide number. As founder Oskar Zupančič explained: “Making the LSD taught us lots about existing light sources and different qualities of light. As underwater photographers we felt we could bring something new to the strobe market with, although it sounds slightly funny, a strobe fully focused on quality of light” (^[2]).

The company has iterated through four generations of strobes: the original Flash (2017), the Prime and Pro (2020), the Pro X and Prime X (2021), and the Pro Max, Prime, and Pure (announced 2023). Each generation retained the same body dimensions and A1 bayonet mount while improving internals.

Retra Before Strobes: The LSD and Accessories

Before entering the strobe market, Retra built its reputation through innovative lighting accessories:

• 2012-03: Released the Light Shaping Device (LSD), an optical snoot using custom-coated lenses to focus strobe output into shaped beams. Available for Seacam, Ikelite, Sea & Sea, Subtronic, and Inon strobes at €599 (^[3]). The company was founded by Oskar Music, Jure Novak, and Luka Mali (^[4]).
• 2012-08: Released third-generation LSD in three tiers (basic/pro/exclusive) with redesigned optics and patented optical elements, starting at €499 (^[5]).
• 2012-10: Announced the Pilot Light Enhancement (PLE) module for the Inon Z-240, straightening the aiming light beam for better LSD alignment at €48 (^[6]).
• 2012-12: Announced the eZoom, a motorized zoom system developed with Italian photographer Michele Davino for creating zoom-blur effects underwater (^[7]).
• 2013-02: Released the LSD Prime at €349, using the same lens technology as the LSD Pro but in a simpler housing. Alex Mustard reviewed it extensively, noting the LSD had already won a gold medal for Slovenia at the CMAS World Championship of Underwater Photography (^[8]).
• 2013-10: Announced the uTrigger, a wireless underwater remote trigger operating through housing walls at €245 (^[9]).
• 2015-12: Released the LSD Ultimate at €300, with lighter aluminum housing and modular design separating the optical tube from the mounting module, making it strobe-interchangeable (^[10]).

Generation 1: Original Retra Flash (2017)

Development and Preview

Alex Mustard first heard about the Retra Flash project in mid-2015, gave feedback on an early prototype in early 2016, and tested a working prototype alongside six other major strobes (Seacam 150, Subtronic 270, Sea & Sea YS 250, Ikelite DS161, Inon Z240, and Sea & Sea D1) in the Bahamas in early 2017 (^[11]). His preview was published on February 1, 2017, with the flash available for pre-order the same day at an early-bird price of €499 (rising to €699 after first shipment).

Specifications

(^[12], ^[13])

Design Philosophy

Mustard’s dry tests showed the Retra Flash matched the guide number of the Inon Z-240, Sea & Sea YS-250, and Ikelite DS161 (all GN 16 at ISO 100 in meters) while providing a wider, more even spread of light. The Sea & Sea D1 recorded a higher GN of 18 but had noticeably narrower coverage. Only the Seacam 150 (GN 22) and Subtronic 270 (GN 25) exceeded it in raw power, at considerably higher prices (^[14]).

Key design features included:

• Bayonet-mount diffuser system: The A1 bayonet allowed quick changes between wide angle diffuser (included), white diffuser, shark diffuser, protection ring, reduction ring, and LSD snoot (^[15]).
• Differentiated control knobs: Two knobs of different lengths for mode and power, distinguishable by touch (^[16]).
• Heat protection: Built-in heat fuses that temporarily disable the strobe if critical areas overheat, preventing damage from repeated full-power firing. Oskar stated they tested 1,000 full-power flashes at 2-second intervals without failure (^[17]).
• Sealed battery compartment: Isolated from electronics; flooding covered by warranty (^[18]).
• SOS mode: Emergency light signal capability (^[19]).

Field Review

The full field review was published September 20, 2017, with images from Mustard and six other photographers tested in the Red Sea, Grand Cayman, and Cuba. Mustard distributed strobes to Valerie Reid, Horacio Martinez, Robert Smits, Peter Berndt, Josef Litt, and Nick More on his workshops. Feedback included:

• Josef Litt: “I used the Retra’s on half power, while I had to use the INONs on 11 or full to light a reef scene”
• Nick More: “I was impressed with the power and quality of light, even shooting into a bright sunball”
• Valerie Reid: “Retra Flashes will be my next new strobes, I am so impressed that I will purchase them”
• Peter Berndt: “they were more powerful and had a faster recycling time than my INONs”

Battery compartment ergonomics were noted as a weak point by multiple testers. Mustard fully disclosed his collaborative relationship with Retra throughout (^[20]).

Production Crisis and Discontinuation

Despite strong demand, Retra could not scale production. Average delivery times stretched to 10-12 weeks. In April 2018, Retra ceased production of the original Flash, with Backscatter informing customers that “these plans do not include production of any strobes in 2018” (^[21]). Oskar explained the company had to choose between production/sales and development, opting to “focus solely on development of a new Retra Flash” (^[22], ^[23]). Retra emphasized that all warranty and servicing obligations would continue to be honored.

Comparative Testing (2018)

Wetpixel Editor Adam Hanlon published a three-way strobe comparison test in February 2018, pitting the Retra Flash against the Inon Z-330 and Symbiosis SS-2 in the Red Sea at Emperor Divers, Marsa Alam. The strobes were loaned by their respective manufacturers/distributors (^[24]).

Generation 2: Prime and Pro (2018 announcement, 2020 shipping)

Announcement

In November 2018, Retra announced two new strobes: the Flash Prime (100 W/s, €599) and Flash Pro (150 W/s, €739), with a planned shipping date of May/June 2019 (^[25]). These represented major advances over the original Flash while retaining the same body dimensions and A1 bayonet mount.

Key Improvements Over Original

(^[26])

The most significant innovations were:

• Fully circular flash tube: A world first for underwater strobes, producing smoother, more even light output (^[27]).
• Bluetooth smartphone connectivity: The first underwater strobe with smartphone app connectivity (patent pending) for configuring HSS, Smart SL mode, and firmware updates via the Retra UWT App (^[28]).
• High-Speed Sync (HSS): Enabling shutter speeds up to 1/8000s for creative ambient light control (^[29]).
• Leakage detector (patent pending): Active flood warning system (^[30]).
• Fiber-optic-only triggering: Electrical sync moved to an optional external electro-optical converter (^[31]).

Shipping and Testing

After significant delays (originally planned for mid-2019), the Prime and Pro began shipping in January 2020 at revised prices of €799 and €899 respectively (^[32]). Retra stated the strobes underwent 1.4 million combined test shots during development.

The Pro’s 3-second recycle time at full power drew criticism. Commenter Alex Ribeiro called it “a deal breaker.” Oskar responded that the strobe would fire even if recycling was not complete, a feature designed for action photography, and that an extended battery pack would halve recycle times (^[33]).

TTL and HSS Support

In February 2020, UW Technics announced updated firmware for their Nauticam-mounted Sony TTL converters supporting the Retra Pro, including HSS capability. The converter could drive HSS shutter speeds from 1/320 to 1/8000s with the Retra Pro, with the strobe itself generating the pulsating flash pattern. TTL profiles for the Retra Pro were set via position 7 on the converter’s rotary switch (^[34], ^[35]).

Comparative Review with Scubalamp D-Max

In April 2021, photographers Hannes Klostermann and Giacomo Rossi published a comparative review of the Retra Pro and Scubalamp D-Max on Wetpixel. Both purchased strobes for personal use (Klostermann at full price, Rossi at a discount). The review was conducted in La Paz, Mexico (^[36]). Community feedback noted that the Retras required Eneloop Pro batteries specifically; older or other-brand rechargeable AAs could cause reliability issues (^[37]).

Supercharger Battery Pack

Original Battery Extender

The original Flash offered a battery compartment extender that replaced the standard battery door, increasing capacity from 4 to 8 AA batteries (^[38]).

Supercharger for Prime/Pro

In June 2020, Retra announced the Supercharger, a redesigned external battery pack for the Prime and Pro (not compatible with original Flash units). Pre-order price was €199, rising to €239 (^[39]).

The Supercharger added 4 more AA batteries (8 total), featuring double O-ring seals on all surfaces and a robust threaded-rod attachment mechanism. It reduced Pro recycle time by more than 50% and doubled battery life. With Supercharger, purchasing one also extended the warranty by 6 months (^[40]).

(^[41])

Adam Hanlon reviewed a prototype Supercharger in June 2020, conducting surface and underwater recycle tests during COVID-restricted UK diving conditions. His testing confirmed Retra’s claims: the Supercharger roughly doubled recycling rate and flash count (172 vs 362 average full-power flashes). He noted the Supercharger felt “very much like an integrated component” with zero wobble, but added that it made tucking strobes close to the port more difficult and introduced additional O-ring maintenance (^[42]).

Retra Reflector

In October 2020, Retra introduced the Reflector, a machined aluminum accessory with a reflective coating that snaps onto the strobe head. Priced at €99, it boosted light output by approximately 2/3 to one full stop while narrowing beam spread, allowing photographers to shoot at lower power levels with faster recycle times (^[43]).

Reviewer Mike Bartick tested it in Anilao, Philippines with a Nikon D850, shooting macro, wide angle, close-focus wide angle, and blackwater subjects. He found the light quality “rich with natural contrast” with no hot spots or unnatural patterns. Combined with the Supercharger, he reported 500+ exposures per day with no battery concerns (^[44]). Alex Mustard and Adam Hanlon discussed the Reflector on Wetpixel Live the same day (^[45]).

Firmware and Warranty Updates

In February 2021, Retra released firmware version 3.6 and reset warranties for all Prime/Pro owners who received strobes before December 1, 2020, acknowledging that COVID-19 had limited diving opportunities. Key firmware improvements included:

• Faster recycle times and lower power consumption in HSS mode below 50%
• Fix for uneven HSS illumination bug causing black/white stripes with some cameras
• New “always batt” mode for continuous battery level display
• Error override function for false alarms
• Resolved optical signal processing bug in TTL mode with Supercharger that caused false triggers
• Adjustable pilot light intensity (Pro only) saved per power level

A follow-up firmware 3.12 was released days later to fix unwanted TTL flashes with Supercharger and fully charged batteries (^[46]).

Generation 3: Pro X and Prime X (2021)

Announced in March 2021 to celebrate Retra’s 10th anniversary, the Pro X and Prime X offered incremental improvements while maintaining full backward compatibility with all existing accessories:

• 25% faster recycle times via optimized flash triggering
• 20% more flashes per battery charge
• 8% lighter housing
• Redesigned optical sensing module with improved signal processing
• Direct mounting for E-Opto converter (no cable needed)
• Improved TTL accuracy and maximum power output
• Reinforced mode and power dials
• Dedicated HSS mode on control panel
• New Supercharger X, 25% lighter than predecessor

Prices were €899 (Prime X) and €999 (Pro X), shipping from early May 2021 (^[47]). The announcement was accompanied by a Wetpixel Live episode in which Adam Hanlon interviewed Oskar about Retra’s first decade (^[48]).

Adam Hanlon used the Pro X extensively during a two-week Wetpixel Red Sea Photographic Odyssey and provided a video review in June 2022 (^[49]). User Peter Korn reported success with the macro/super-macro reduction accessories but found the LSD difficult to use, describing it as “best suited for super-macro only” (^[50]).

Generation 4: Pro Max, Prime, and Pure (2023)

By mid-2023, Retra announced fourth-generation strobes. The Pro Max (190 W/s) was a significant power increase over the Pro X (150 W/s), and crucially redesigned the battery system to accept 8 AA batteries natively rather than requiring a separate Supercharger module. Forum contributor Walt Stearns, who had owned every Retra generation, noted: “The game changer for me is not because they are 40 Ws more powerful at full power, its that Retra has changed the solution to being able use 8 AA’s straight away with a cleaner easier system” (^[51]).

The new Pure model was introduced as an entry-level offering. Some Pro X owners expressed frustration at the rapid product cycle; the Pro X had only been available for roughly two years before being superseded (^[52]).

Note: The April 1, 2023 article “Retra Announces Voice Control Firmware” was an April Fools’ joke, though it teased the upcoming 4th generation: “the new Retra Flash series will not have voice recognition but it will have cutting-edge underwater strobe technology” (^[53]).

LSD Compatibility

The Retra LSD snoot was a key differentiator for the Flash system. In April 2018, Retra released a mounting kit for the LSD to work with the Inon Z-330 strobe, available as a complete unit or upgrade kit (€25) for existing LSD owners. Retra noted that the Z-330’s angled pilot light worked better as an aiming light with the LSD than the Z-240’s (^[54]).

Known Issues

Battery Sensitivity

Multiple users reported that the Prime/Pro strobes were sensitive to battery quality and required Eneloop Pro batteries specifically. Older rechargeable AAs or other brands could cause the strobe to switch off or behave erratically. Josef Litt noted during the original Flash testing: “I had one battery set that was not top notch and the strobe kept switching off” (^[55]). Andrea Severino reported with the Pro: “I had to use Eneloop Pros and buy them new” (^[56]).

Deep Diving Flood Incident

In September 2023, a diver reported both Retra Pro X strobes with Superchargers flooding simultaneously at 89 meters (293 feet) — within the 100m rated depth. Both strobes had worked at 45 meters the previous week and had not been opened between dives. Retra’s initial response was that “any flooding in the battery compartment is not covered under warranty” since the sealing is user-operated, and that the leakage detector only works when the strobe is turned on. The diver pushed back, arguing that simultaneous failure of four O-rings indicated a manufacturing defect. The incident generated 96 replies and significant community discussion about warranty obligations (^[57]).

Community Discussion

• RETRA Strobe Thread (707 replies) — The primary community thread for Retra strobe owners, started February 2017 by guyharrisonphoto. Oskar from Retra actively participated, answering technical questions about battery compatibility, sync cables, and accessories. The thread spans the full product lifecycle from pre-order through multiple generations (^[58]).
• RETRA Discontinued? (26 replies) — Community reaction to the April 2018 production halt, with Oskar explaining the decision and reassuring warranty coverage (^[59]).
• Inon Z330 vs Retra Pro (52 replies) — Detailed comparison discussion. Users praised the Retra’s build quality (“tank-like”), circular flash tube, and easy O-ring maintenance, while noting battery consumption and the company’s “hibernation” period as concerns (^[60]).
• HSS Retra Strobe (51 replies) — Technical discussion of HSS implementation with UW Technics converter and Sony cameras. Pavel Kolpakov from UW Technics confirmed HSS pulsating flash is generated by the Retra strobe itself (^[61]).
• New Retra Strobes…Regrets? (12 replies) — Pro X owners discussing the rapid product cycle after 4th generation announcement. Community consensus was pragmatic: the Pro X remained fully capable (^[62]).
• Both Retra Strobes Flood at 89 Meters (96 replies) — Detailed incident report and warranty dispute over simultaneous deep-water flooding (^[63]).
• Review: Retra Flash Pro and Scubalamp D-Max (9 replies) — Forum discussion of the Klostermann/Rossi comparative review (^[64]).
• Snoot aiming advice - Retra LSD (13 replies) — Practical tips for aiming the Retra LSD snoot, including infrared aiming light techniques (forum thread, topic 64210).
• Retra LSD Prime (4 replies) — Early user images and impressions of the LSD Prime snoot (forum thread, topic 50249).

Timeline

• 2011: Retra Underwater Technology founded in Slovenia (^[65]).
• 2012-03: LSD (Light Shaping Device) optical snoot released at €599 (^[66]).
• 2012-08: Third-generation LSD in three tiers released (^[67]).
• 2012-10: Pilot Light Enhancement (PLE) module announced (^[68]).
• 2012-12: eZoom motorized zoom system announced (^[69]).
• 2013-02: LSD Prime released at €349; field reviewed by Alex Mustard (^[70], ^[71]).
• 2013-10: uTrigger wireless remote release announced at €245 (^[72]).
• 2015-12: LSD Ultimate released at €300 with modular design (^[73]).
• 2017-02: Retra Flash previewed by Alex Mustard; pre-orders open at €499 (^[74], ^[75]).
• 2017-09: Retra Flash field reviewed and begins shipping at €699 (^[76]).
• 2018-02: Three-way strobe comparison test published (Retra Flash vs Inon Z-330 vs Symbiosis SS-2) (^[77]).
• 2018-04: Retra ceases original Flash production due to inability to meet demand (^[78]). LSD mounting kit released for Inon Z-330 (^[79]).
• 2018-11: Retra Flash Prime (100 W/s) and Pro (150 W/s) announced with circular flash tube, Bluetooth, HSS, and leakage detector (^[80]).
• 2020-01: Prime and Pro begin shipping at €799/€899 after extended delays (^[81]).
• 2020-02: UW Technics releases TTL/HSS firmware for Retra Pro with Sony cameras (^[82]).
• 2020-06: Supercharger battery pack announced at €199 (^[83]); reviewed by Adam Hanlon (^[84]).
• 2020-10: Reflector accessory released at €99; field reviewed by Mike Bartick (^[85], ^[86]).
• 2021-02: Firmware 3.6 released; COVID warranty extension for existing owners (^[87]).
• 2021-03: Pro X and Prime X announced for Retra’s 10th anniversary (^[88], ^[89]).
• 2021-04: Comparative review with Scubalamp D-Max published (^[90]).
• 2022-06: Adam Hanlon publishes Wetpixel Live Pro X review after Red Sea trip (^[91]).
• 2023: Fourth-generation strobes (Pro Max, Prime, Pure) announced with integrated 8-AA battery system (^[92]).
• 2023-09: Dual flooding incident at 89m reported (^[93]).

References

Wetpixel Live