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Sea&Sea Announces Sony Alpha Universal Housing
By Ian Bongso-Seldrup, July 31, 2022 @ 11:00 PM (EST)

Sea&Sea has announced a new housing offering “universal compatibility” with the current full-frame cameras in Sony’s Alpha series. According to Sea&Sea, the MDX-αU supports the “entry-level” a7 Mark IV, “high-resolution” a7R Mark IV, “video-centric” a7S Mark III, “pro sports” a9 Mark II, and “8K-capable” a1. The company says the housing is “a sustainable design that can be used with new cameras in the future with minimal parts replacement.” As a result of the “universal” design, initial mounting of the camera is a little more involved, there are some functional limitations that require workarounds, and optional additional kits are needed to enhance compatibility with certain models. (See the product information below for more details.)

The new “future-oriented” housing looks very similar to Sea&Sea’s dedicated a7R Mark IV housing—including the eye-catching yellow accents—but it boasts a number of improvements. First, the housing features a much larger acrylic back panel, which reduces weight and aims to provide better visibility of the LCD. Second, there’s a new fiber-optic cable cover, which is designed to protect the connectors and prevent them from falling out. Third, the company’s Leak Alarm Unit is now included as standard equipment rather than as an option. Also, unusually for the Japanese company, the housing is available in a silver finish as well as the tradtional black.

The MDX-αU supports fiber-optic connectivity with compatible Sea&Sea YS strobes in TTL or manual modes via the optional Optical YS Converter S1 or Manual Flash Trigger, respectively. If you trigger your YS strobes via sync cords, you also have the option of an electrical connection.

Consult your local dealer for pricing and availability. Backscatter is currently taking pre-orders.

When purchasing underwater photography equipment like the product mentioned in this article, please support DPG by supporting our retail partner—Backscatter.com.


Sea&Sea MDX-αU Underwater Housing for Sony α1/α9II/α7sIII/α7RIV/α7IV
Universal compatibility with Sony Alpha series. The future-oriented mirrorless SLR compatible housing is now fully loaded


Universal design for the future. The back panel is designed to be large

The back acrylic panel is more than twice as large as before to improve visibility of the monitor and reduce the underwater weight. Furthermore, it is a sustainable design that can be used with new cameras in the future with minimal parts replacement.

Newly designed fiber-optic cable cover Newly designed optical fiber cable cover

Newly designed fiber-optic cable cover included. Prevents optical cable terminals from falling out and smartly protects light-emitting panels and cable terminals. Includes a strap to prevent loss of the cover.

Leak Alarm Unit as standard equipment

The Leak Alarm Unit, which was previously available as an option, is now included as standard equipment. It is effective not only for early detection of underwater flooding accidents, but also for protection of equipment by checking its waterproof performance before entry. CR2032 lithium battery included.

Strobe Synchro System

Three optional strobe connection methods are available.

1. Optical TTL connection
[Product No.50139]  Optical YS Converter S1

Compatible with SEA&SEA “Optical YS Converter S1” which converts the strobe light emission signal of the camera to LED light and synchronizes with the SEA&SEA YS strobe. It is a high-performance converter that does not just emit simple light-emitting signals, but also performs TTL auto light control.
*Sony original adapter “ADP-MAA” is required separately for connecting camera and optical YS converter.

2. Optical manual connection
[Product No.50146]  Manual flash trigger

For those who do not need TTL photography, the fiber-optic cable connection enables manual firing of the YS strobe.

3. Electrical connection
[Product No.50147]  Strobe connector/N
[Product No.50122]  Optional Sync Cord 2-pin Connector

YS strobes can be electrically connected with a sync cord.

Full range of standard equipment

  • Grip Plus made of silicone material
  • Robust yet secure fit to hold the housing in place
  • Lighting can be deployed as desired from the SA8 fixed ball base
  • Pre-equipped with lanyard hooks for convenient transportation

Functional Limitations and Enhancement Customization Kit

Common to all models

  • Up/down/left/right buttons on the multi selector cannot be used
  • Use the up/down/left/right buttons on the control wheel instead
  • The up/down/left/right buttons on the control wheel cannot be used to move the focus point
  • Focus point can be moved with the front and rear dials using the camera’s dial customization function

α1/α9II camera

  • Drive mode/focus mode dials are not available as standard
  • It can be supported by using the optional kit
  • If you want to change the drive mode etc. without modification, you can temporarily use it by registering the camera’s custom shooting setting in advance and calling up the function, but it is not a perfect substitute

α7IV camera

  • The shooting mode lever cannot be used
  • This can be handled by using an optional kit
  • S&Q cannot be used

[Product No.50148] α1 customize kit for MDX-αU
Compatible with drive mode dial/focus mode switching lever.

[Product No.50149] α9II Customize Kit for MDX-αU
Compatible with drive mode dial and focus mode selection lever.

[Product No.50150] α7IV Customize Kit for MDX-αU
Compatible with shooting mode selection lever.

MDX-αU Other Features


  • The Port Lock prevents the port from turning or loosening and the Port Lock lever is specifically located to avoid being unlocked accidentally
  • The housing is equipped with a lens-lock release button which makes it possible to change lenses easily, without opening the housing
  • Pulling out the Focus/Zoom Dial gives sufficient room inside the housing to easily accommodate larger diameter lenses
  • Equipped with the Optical Viewfinder 0.5x as standard. Other optional viewfinders such as the VF180 1.2x, VF45 1.2x and Optical Viewfinder 0.66x, 0.8x can be used
    ※Some vignetting occurs.When the VF180 1.2x is mounted on housing, the uper part of the camera's viewfinder cannot be viewed due to vignetting
  • Equipped with two sacrificial zinc diodes (one on the front case and the other on the rear) to prevent electrolysis damage
  • Tripod screw mount is located on the centre underside of the housing



[Construction] Body: corrosion-resistant aluminum alloy (machined)
  Grip: corrosion-resistant die-cast aluminum alloy
[Depth rating] 100m / 330ft
[Dimensions (WxHxD)] 330 x 169 x 137 mm / 12.9 x 6.6 x  5.4 inches
[Weight] Approx. 2,900g / 102.3oz (Housing only)

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