Retra Underwater Technology

Type: Strobe and lighting accessory manufacturer
Founded: ~2010–2011, Slovenia
Founder: Oskar Marko Music (also known as Oskar Zupancic, General Manager)
Key people: Oskar Zupancic (founder/GM), Jure Novak, Luka Mali
Key products: Light Shaping Device (LSD) snoot, Retra Flash, Flash Pro/Prime, Pro X/Prime X, Supercharger, Reflector, uTrigger
Website: retra-uwt.com

Overview

Retra Underwater Technology (Retra UWT) is a Slovenian company that entered the underwater photography market around 2010–2011 with an innovative optical snoot — the Light Shaping Device (LSD) — and expanded into strobe manufacturing in 2017. Founded by Oskar Marko Music (who later used the name Oskar Zupancic in professional contexts), the company grew out of Slovenia’s strong underwater photography community, which borders both Austria and Italy. (^[1])

Retra’s origin story traces to 2010, when Music — then barely twenty years old — contacted Slovenian photographer Borut Furlan with an idea for projecting shaped light underwater from a distance, solving the limitations of conventional tube snoots. Music had already filed for patent protection. He and Furlan independently developed prototype LSDs on Seacam strobes, completing them by late October 2010. (^[2])

The company introduced several industry firsts over the following decade:

• World’s first underwater strobe with a fully circular flash tube (Flash Prime/Pro, 2020) (^[3])
• First underwater strobe with smartphone connectivity via Bluetooth (patent pending) (^[4])
• First with built-in leakage detection (patent pending) (^[5])
• Optical snoot (LSD) system using focused, collimated light projection rather than reductive tube snoots (^[6])

Zupancic was personally active on the Wetpixel forums and article comments throughout the company’s history, responding directly to customer questions, technical inquiries, and warranty disputes. (^[7])

Origins and the LSD

The LSD’s design differs fundamentally from conventional snoots. Traditional tube snoots block most of a strobe’s light output to create a small spotlight, requiring close proximity to the subject and wasting power. The LSD instead collects the strobe’s output through a light collector, passes it through interchangeable aperture plates (which shape the beam into circles, squares, or custom shapes), and then projects it through a coated lens — functioning as a miniature light projector. This produces a collimated beam that maintains focus at a working distance of approximately 166–246mm underwater (depending on lens), allowing photographers to illuminate subjects from much farther away without scaring them. (^[8])

Borut Furlan’s 2011 review for Wetpixel — the first detailed published assessment — found light loss of only one to two f-stops, far less than conventional snoots. The review confirmed the LSD could be used with both macro and fisheye wide-angle lenses. Furlan noted that while the device delivered on its theoretical advantages, it was suitable for experienced photographers only, requiring practice to master the positioning. (^[9])

Retra LSD snoots quickly gained a following in the European competition circuit. Slovenian photographer Rok Kovacic won a gold medal in the macro category of the official CMAS World Championship of Underwater Photography using an LSD. (^[10])

Key People

• Oskar Marko Music / Oskar Zupancic — Founder and General Manager. Invented the LSD as a teenager, filing patents before the age of twenty. Personally engaged with the Wetpixel community under the username “Oskar@RetraUWT,” answering technical questions, acknowledging warranty issues, and discussing product development. (^[11], ^[12])
• Jure Novak and Luka Mali — Co-founders listed in early company descriptions. (^[13])
• Alex Mustard — Associate editor of Wetpixel and prominent underwater photographer who collaborated with Retra for several years, providing feedback on prototypes from mid-2015 onward. Authored multiple Wetpixel reviews of Retra products. Disclosed his collaborative relationship but stated he was not paid and did not benefit from sales. (^[14], ^[15])
• Mike Bartick — Macro specialist who field-reviewed the Retra Reflector in 2020. (^[16])

Product Timeline

LSD Accessories (2011–2018)

• 2011-09: First published review of the LSD by Borut Furlan on Wetpixel, documenting tests on a Seacam 250 strobe. LSD initially available for Seacam 150 and 250, with Inon Z-240 compatibility in development. Pre-order price: €995. (^[17])
• 2012-03: LSD formally released for purchase. Available for Seacam 150/250, Ikelite 125ds, Sea&Sea YS110/YS250Pro, Subtronic Pro 270, and Inon Z-240. Constructed of aluminum with AR-coated lens, supplied with 8 aperture plates. Price: €599. (^[18])
• 2012-08: Third-generation LSD released in three tiers (Basic, Pro, Exclusive). Redesigned optical system with newly patented elements, improved contrast, and argon-gas assembly environment for the Exclusive model. Starting price: €499. (^[19])
• 2012-10: Pilot Light Enhancement (PLE) module announced for use with Inon Z-240. Straightens the Z-240’s aiming light beam for better LSD alignment, at the cost of one stop of strobe power. Price: €48. (^[20])
• 2012-12: eZoom motorized zoom system announced, developed in conjunction with Italian photographer Michele Davino. An aluminum housing containing an electric motor to drive a lens zoom ring underwater, enabling zoom-blur effects. The community reception was skeptical, with one commenter suggesting it should have been saved for April 1st. Price and availability were not finalized. (^[21])
• 2013-02: LSD Prime released — lower-cost snoot using the same lens technology as the Pro model, with 13 standard light projection shapes. Compatible with Inon, Ikelite, Sea&Sea, Subtronic, and Seacam strobes. Price: €349. (^[22])
• 2013-02: LSD Prime field review published by Alex Mustard on Wetpixel. Mustard confirmed it was slightly less light-efficient than the Pro but “close to indestructible.” He demonstrated its use for macro spotlights, wide-angle isolation, creative backlighting, and “dark field” illumination techniques. (^[23])
• 2013-10: uTrigger wireless remote trigger announced. Works through housing walls (up to 20mm aluminum) via wireless signal, supporting both AF and manual focus modes, with bulb/lock functions for long exposures. Universal design works across camera/housing combinations. Price: €245. (^[24])
• 2015-12: LSD Ultimate released — lighter aluminum housing with separate, interchangeable optical tube and mounting module. Minor optical improvements over the Prime. Mounting modules available for Sea&Sea, Inon, Seacam, and Ikelite strobes (€80 each). LSD Ultimate price: €300. Three new mask packs (Standard, Creative, Circular) at €40 each. (^[25])
• 2018-04: LSD mounting kit released for Inon Z-330 strobe, available as complete unit (€299) or upgrade kit for existing Z-240 owners (€25). Retra noted the Z-330’s angled pilot light works better as an aiming light with the LSD than the Z-240. (^[26])

Retra Flash — 1st Generation (2017–2018)

• 2017-02-01: Retra Flash previewed by Alex Mustard on Wetpixel. Mustard disclosed he first heard about the strobe in mid-2015 and gave feedback on prototypes in early 2016. He field-tested a working prototype in the Bahamas alongside Seacam 150, Subtronic 270, Sea&Sea YS-250, Ikelite DS161, Inon Z-240, and Sea & Sea D1. The Retra matched the guide number (GN 16 at ISO 100) of the Z-240, YS-250, and DS161 while providing wider, more even coverage. Specs: 100Ws, 5500K (4700K with diffuser), 95deg beam (110deg with diffuser), 4xAA, 2.5s recycle time, 9 power levels, Sea&Sea 5-pin electronic sync + dual optical connector. Pre-order price: €699 (early-bird discounts from €499). (^[27])
• 2017-02-01: Oskar Zupancic posted directly in the Wetpixel comments, identifying himself as “founder and managing director at Retra” and fielding dozens of technical questions. He confirmed: sealed battery compartment separate from electronics, heat fuses for overheating protection, battery pack accessory planned at ~€99, and that the Nauticam compatibility issue was prototype-only. (^[28])
• 2017-02-02: Full specifications published. (^[29])
• 2017-09: Retra Flash field review published by Alex Mustard, with contributions from six other photographers who tested the strobes on workshops in the Caribbean and Red Sea. Nine photographers used the strobes across different Nikon and Canon bodies, triggered both electronically and via fiber optic. Mustard and contributors praised the power, warm light quality (4500K with wide diffuser), and intuitive controls. Minor issues: tight battery compartment, sensitivity to old batteries. The bayonet-mount diffuser system was highlighted as a major advantage, enabling quick changes between Wide Angle Diffuser, White Diffuser (for green water), Shark Diffuser (warm, less diffused for distant subjects), Protection Ring, Reduction Ring, and LSD. Shipping began September 22, 2017, at €699. (^[30])
• 2018-02: Wetpixel editor Adam Hanlon published a comparative strobe test of the Inon Z-330, Retra Flash, and Symbiosis SS2 in the Red Sea. The review used Emperor Divers in Port Ghalib as a base. (^[31], ^[32])
• 2018-04: Retra ceases production of the original Flash. The company cited inability to keep up with demand due to production time constraints, deciding to halt production and refine their manufacturing process. Retra emphasized continued production of LSD accessories and honoring of all warranties and servicing. (^[33])

Flash Prime & Pro — 2nd Generation (2018–2021)

• 2018-11: Flash Prime (100Ws, €599) and Flash Pro (150Ws, €739) announced as a complete redesign. Key changes from the original: color temperature shifted from 5400K to 4900K, beam angle widened from 110deg to 130deg, power levels increased from 9 to 13, HSS-ready, optional leakage detector (standard on Pro), fiber optic triggering as standard (electrical via optional converter rather than built-in). Housing dimensions retained for accessory compatibility. Pre-orders opened with May/June 2019 planned shipping. (^[34])
• 2020-01: Flash Prime (€799) and Flash Pro (€899) begin shipping — significantly delayed from the original May/June 2019 target. Marketing highlighted the world’s first fully circular flash tube in an underwater strobe, smartphone connectivity via Bluetooth (patent pending), and built-in leakage detection (patent pending). Retra claimed 1.4 million combined test shots during development. The Pro offered 150Ws with 500-lumen pilot light; the Prime offered 100Ws with 300-lumen pilot light. Both used 4xAA batteries with fiber optic triggering. (^[35])
• 2020-02: UW Technics released firmware for their Nauticam-mounted Sony TTL converters supporting Retra Pro Flash TTL and HSS. The firmware was developed in cooperation with Retra and supported HSS shutter speeds up to 1/8000s with manual strobe power adjustment. (^[36])
• 2020-06: Supercharger battery pack announced for pre-order (€199, rising to €239 after June 30). Uses 4 additional AA batteries (8 total), double O-ring seals, reduces recycle time by more than 50% and more than doubles battery life. Pro with Supercharger: 0.7s recycle to 40% power, 350+ full-power flashes. Purchasing a Supercharger extended the flash warranty by 6 months. (^[37])
• 2020-06: Supercharger prototype reviewed by Wetpixel editor Adam Hanlon. Testing confirmed approximately doubled recycling rate and battery life (172 vs 362 average full-power flashes). The Supercharger was praised as “beautifully engineered” with zero lateral play. Hanlon noted the Supercharger makes it harder to tuck strobes close to the port for macro, and adds O-ring maintenance burden. (^[38])
• 2020-10: Retra Reflector previewed on Wetpixel Live and field-reviewed by Mike Bartick. A polished aluminum attachment that decreases beam spread but intensifies power by approximately 2/3 to one full stop. Bartick found it suitable for macro, wide angle, close focus wide angle, and blackwater photography, with no hot spots or unnatural light patterns. The power boost allowed shooting at lower strobe power, extending battery life and reducing recycle times. Price: €99. (^[39], ^[40])
• 2021-02: Warranty extension and firmware update (v3.6) announced. Due to limited diving opportunities during COVID-19, Retra reset warranties for all strobes delivered before December 31, 2020, with the new warranty period starting January 1, 2021. Firmware v3.6 included: faster HSS recycle times, resolved HSS uneven illumination bug, new “always batt” battery indicator mode, error override function, improved pilot light adjustment (Pro), resolved TTL/Supercharger false trigger bug. A follow-up firmware v3.12 was released days later to fix additional TTL issues. (^[41])
• 2021-04: Comparative review of Scubalamp D-Max and Retra Flash Pro published by Hannes Klostermann and Giacomo Rossi, who purchased the strobes independently. (^[42])

Pro X & Prime X — 3rd Generation (2021–2023)

• 2021-03: Pro X (€999) and Prime X (€899) announced to celebrate Retra’s 10th anniversary. Improvements: up to 25% faster recycle times, up to 20% more flashes per battery charge, 8% lighter housing, redesigned optical sensing module, direct mounting for E-Opto converter (no cable needed), improved TTL accuracy, reinforced control dials, and dedicated HSS mode switch. All existing accessories remained compatible. A lighter Supercharger X (25% weight reduction) was also introduced. Shipping began early May 2021. (^[43])
• 2021-03: Wetpixel Live episode featured Zupancic discussing Retra’s first ten years with Adam Hanlon. (^[44])
• 2022-06: Wetpixel Live review of Pro X flash by Adam Hanlon, based on a two-week Red Sea Photographic Odyssey trip. Retra loaned the strobes and accessories. (^[45])
• 2023-04-01: Retra published an April Fools’ article announcing “Siri Flash Voice Control” firmware, joking about voice-controlled strobe settings. The prank included a reveal that a genuine new strobe series was forthcoming. (^[46])

Pro Max — 4th Generation (2023)

• 2023-06: 4th-generation Pro Max, Prime, and Pure models announced. Key change: integrated 8xAA battery compartment eliminated the need for the separate Supercharger module, removing failure points and O-rings. A status display was added. Zupancic confirmed the 4th generation implemented additional systems to detect which battery compartment is mounted regardless of voltage levels. Community discussion on the Wetpixel forums revealed mixed feelings — some Pro X owners felt their recently purchased strobes were obsoleted too quickly, while others noted the incremental nature of the improvements. Walt Stearns, who owned three Prime (2nd gen) strobes, described the 8xAA integrated design as the “game changer” justifying the upgrade. (^[47])

Community Reception

Praise

Retra strobes earned strong community endorsements from professional and amateur underwater photographers alike. The circular flash tube design was widely praised for producing more even illumination than conventional straight-tube strobes, reducing hot spots and edge backscatter. (^[48])

Alex Mustard’s detailed 2017 field review, which included testimonials from six other photographers, established the brand’s reputation. Community reactions were overwhelmingly positive. Valerie Reid: “Retra Flashes will be my next new strobes, I am so impressed that I will purchase them.” Josef Litt: “I would not upgrade to them, but I would choose them over my INON Z240s.” (^[49])

The bayonet-mount accessory system — enabling quick swaps between wide angle diffusers, shark diffusers, white diffusers, protection rings, reduction rings, reflectors, and LSD snoots — was seen as a significant innovation, giving photographers field-adjustable light quality. (^[50])

Color Temperature Debate (~4900K)

A persistent community concern involved the 4900K color temperature of the 2nd and 3rd generation strobes, significantly warmer than Inon strobes (~5500K). Forum user Michael T. reported persistent yellowish tint in green water conditions, particularly noticeable in European waters (Grevelingen, Oosterschelde). Another user (TheOcean) confirmed the same issue with Pro X strobes, describing the result as “Coca-Cola” colored. Retra’s official recommendation was to correct in post-processing. (^[51])

Community workarounds included using Lee filter color gels behind diffusers, using Retra’s White Diffuser (designed for green water), and camera white balance shift functions. Some competition photographers found the color temperature particularly problematic because they needed correct white balance straight from the camera. Multiple users noted the issue was most pronounced in green water and less apparent in blue tropical water. (^[52])

89m Flood Incident (2023)

In September 2023, a diver (forum user “serpentara,” identified as Steven “Drew” Wilson) reported both Retra Pro X strobes with Superchargers flooding simultaneously on a dive to 89 meters (293 feet) — within the strobes’ rated depth of 100 meters. The strobes had been used successfully the previous week to 45 meters and were not opened between dives. The battery compartment caps had popped open, venting battery electrolyte. (^[53])

Zupancic responded publicly on the same forum thread, posting the user’s correspondence for transparency. He emphasized that: the strobes were not turned on during the dive (disabling the leakage detector); the battery compartment sealing is user-operated and excluded from warranty; the main strobe compartment remains sealed and warranted; and Retra had tested Superchargers at depths above 100m even with single/damaged O-rings. (^[54])

The thread generated 96 replies and significant debate. Forum user makar0n questioned the legality of the warranty exclusion under EU law (which mandates a 2-year minimum warranty) and noted that Retra’s public warranty page mentioned coverage for “any issues” without listing exclusions. Other community members debated whether the user’s maintenance practices (not opening battery compartments between deep dives, not rinsing immediately) may have contributed. The incident highlighted the gap between marketing language and warranty fine print, and Retra’s later 4th-generation design addressed some concerns by integrating the battery compartment and eliminating the Supercharger’s additional O-ring sealing surfaces. (^[55])

Rapid Product Cycles

Some community members expressed frustration with Retra’s pace of product releases. When the 4th-generation models were announced in mid-2023, Pro X owners who had purchased less than a year earlier felt their strobes were prematurely obsoleted. However, multiple users noted the improvements were incremental and that existing strobes continued to perform well. One user who had owned original Retra Pro strobes since early 2020 felt “no pull towards the new models.” (^[56])

Technical Specifications Summary

Competition Photography

Retra’s LSD snoots became dominant in European fotosub (on-the-day) competitions, where creative lighting techniques score highly with judges. The LSD Pro was used by Rok Kovacic to win gold in macro at the CMAS World Championship of Underwater Photography. (^[57])

Retra strobes appeared in Wildlife Photographer of the Year 2021 winning images: Jennifer Hayes’ “Nursery meltdown” (Winner, Oceans: The Bigger Picture) was shot with “two Retra strobes.” (editorial)

Wetpixel Live

Retra was featured in two dedicated Wetpixel Live episodes. Episode 186, “Retra UWT Celebrates its 10 Year Anniversary,” featured Adam Hanlon interviewing Oskar Zupancic about the company’s first decade, from the original LSD snoot through four generations of strobes (^[58]). Episode 244, “Field Review: Retra Pro X Flash and Accessories,” presented Hanlon’s detailed assessment of the Pro X strobe after extended Red Sea use (^[59]).

Industry Relationships

• Inon: Retra’s LSD snoots were designed to be compatible with Inon strobes (Z-240, Z-330, S-2000), making Inon the most common base strobe for LSD users before Retra made its own flash. Retra promptly released Z-330 compatibility when Inon updated its strobe line. (^[60])
• UW Technics: Collaborated on TTL converter firmware supporting Retra Pro Flash TTL and HSS for Sony cameras. (^[61])
• Marelux: Third-party compatibility — Marelux SOFT Pro Snoot listed Retra Flash Pro X among compatible strobes. (editorial)
• Sea & Sea: Retra’s original Flash used Sea&Sea 5-pin electronic sync cables as standard, lowering the barrier for upgraders from Sea&Sea and Inon systems. (^[62])

References