Port extensions can serve two purposes in underwater photography, one is purely physical in nature, it simply extends the length of a port to accommodate a longer lens or one equipped with accessories such as tele converter, as it is frequently the case with macro photographic configuration. The other has a direct influence on the optical performance of a lens, the extension ring being used, in this instance, for positioning a dome port as closely possible to a wide angle lens optical center. The wider the lens, the more critical this positioning will becomes, especially true of rectilinear type wide angle lenses covering field of views upward of 90 degrees.

Aquatica has gone to great extent to provide you with the best tools for your photographic needs, providing you with no less than thirteen port extension rings, including four with manual focusing knobs on them, ranging in size from 16.5mm /.65” to a full 97.5mm / 3.82”. This, along with the broad selection of ports at your disposition, makes Aquatica one of the, if not the most, comprehensive and accurate underwater photography system existing at the present.

Dimensions shown are (A) the actual length that the extension rings provides between a housing and a port, if you wish to know the overall physical dimension of an extension, add the bayonet length of .5″ /12.5mm (B) to the (A) measurement.

Every extension ring we manufacture is made of high grade 6061 T6 aluminum alloy, anodized to military specs and pressure tested to a depth in excess of 300ft / 90m. A sturdy, trouble free stainless steel locking mechanism insure that your port is reliably  locked to the extension ring, the latter being safely held in place by the housing own locking mechanism.

To learn how to properly measure for an extension, please refer to our Extension Dimension Chart (PDF).

The following extension rings have a manual focusing knob on their side, these require that a focusing gear be attached to the lens, note that these gears are sold separately. Please refer to your housing’s lens chart for compatibility and availability.