Underwater Technics upgrades older Sea&Sea Canon housings to TTL.

Underwater Technics releases a TTL converter for Sea&Sea MDX Canon housings. Compatible with Retra, Ikelite, and Marelux systems. A second life at an affordable price.

Underwater Technics Enables Older Sea&Sea Canon Housings to Use TTL

A well-maintained Sea&Sea housing can last longer than three generations of camera bodies. The problem is that the original flash exposure mode ages less gracefully than the housing itself. Underwater Technics has just released a solution to fix this without requiring you to buy a new housing.

The Small Device That Changes the Exposure Mode

The Underwater Technics converter replaces the original Sea&Sea "Optical YS-Converter" located at the top of the front of a Canon MDX housing. It is an optoelectronic component powered by a CR2332 battery, rated for 5000 activations. Installation requires no modification to the housing itself, just a simple part replacement.

Once installed, the housing switches from manual mode only to true automatic TTL exposure, with compatibility announced for Sea&Sea, Inon, Ikelite, Retra, Marelux, and Subtronic flashes. On certain models (Sea&Sea YS-D130R, Retra Flash Pro Max II, Marelux Apollo III V2), high-speed synchronization up to 1/8000th of a second also becomes available, with support for burst shooting and front and rear curtain sync.

The listed price is approximately €450, converted from $520, which is the official price on the manufacturer's website.

A Key Question Before Buying: Is TTL Right For Your Diving Style?This type of accessory raises a question that I often ask in my training courses: does TTL solve a problem you actually have, or is it just the option that seems most modern on paper? For a moving subject, in changing visibility, or for a beginner who is still learning to read their light, TTL can be helpful. Once you master manual exposure on a stationary subject, the benefit is sometimes marginal, and some photographers deliberately switch back to manual mode for the predictability of the results.

What I mainly take away from this type of converter is the principle behind it: instead of encouraging people to buy a new housing to gain a function, we can sometimes update the part that really matters. For a Sea&Sea housing owner who was hesitating between keeping their equipment or switching to another manufacturer, this converter changes the equation.

It doesn't replace the fundamental work on when to actually use flash underwater, whether TTL or manual. The basic technique remains the same, only the tool changes.

The AquaExposure training course specifically addresses this choice between natural light and flash, TTL or manual. discover the AquaExposure training course.

Price converted from the official dollar price (current exchange rate). The actual VAT-inclusive price charged by European retailers may vary.

To learn more- Underwater Lighting: Strobes and Lights - Choosing the Right Ones in 2026 - When to Use a Flash in Underwater Photography: The Real Exceptions - Sea&Sea Rig System: Housings for TG and Action Cams - Access the AquaExposure Underwater Photography and Videography Training

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01The Small Device That Changes the Exposure Mode
02A Key Question Before Buying: Is TTL Right For Your Diving Style?This type of accessory raises a question that I often ask in my training courses: does TTL solve a problem you actually have, or is it just the option that seems most modern on paper? For a moving subject, in changing visibility, or for a beginner who is still learning to read their light, TTL can be helpful. Once you master manual exposure on a stationary subject, the benefit is sometimes marginal, and some photographers deliberately switch back to manual mode for the predictability of the results.
03To learn more- [Underwater Lighting: Strobes and Lights - Choosing the Right Ones in 2026](/en/blog/eclairage-sous-marin-strobes-phares-2026) - [When to Use a Flash in Underwater Photography: The Real Exceptions](/en/blog/quand-utiliser-flash-photo-sous-marine-exceptions) - [Sea&Sea Rig System: Housings for TG and Action Cams](/en/blog/sea-sea-rig-system-caisson-tg-action-cam-2026) - [Access the AquaExposure Underwater Photography and Videography Training](/lms)

Questions about the Journal

What is the purpose of the TTL converter from Underwater Technics?

It replaces the original optical converter ("Optical YS-Converter") that is installed at the top of the front housing of a Sea&Sea MDX Canon underwater housing. This allows for automatic flash exposure in TTL mode instead of manual mode only.

With which strobes is this converter compatible?

Sea&Sea, Inon, Ikelite, Retra, Marelux, and Subtronic are all reputable brands. Some models, such as the Sea&Sea YS-D130R, the Retra Flash Pro Max II, or the Marelux Apollo III V2, also offer high-speed sync (HSS) capabilities up to 1/8000th of a second.

What is the price of this converter?

Approximately €450 (converted from $520, the official price listed on the Underwater Technics website). The actual all-inclusive price may vary depending on the retailer.

Do you really need to shoot in TTL mode underwater?

No, it is not mandatory. TTL (Through-The-Lens metering) can be useful for subjects that are moving or in changing conditions, but manual mode often provides more predictable results once you have mastered controlling your lighting. This converter gives you a choice, it doesn't impose a specific method.