Diopters

Diopters for Lens Port Compatibility and Close Focus underwater

An underwater diopter is a corrective lens element placed inside the housing, behind the port and in front of the camera lens. It compensates for refraction that shifts the apparent focus distance underwater, enabling accurate close-range focusing in conditions where standard optics cannot maintain sharpness.

These correction lenses are only needed when a particular lens–port combination cannot achieve focus without one. Required diopter strengths are specified in the lens port tables to ensure compatibility and reliable autofocus operation underwater.

Optical Correction Strength and Installation Details

The diopter power must correspond precisely to the lens and port combination for correct optical behaviour underwater.

• Typical correction values range from +2 to +4, depending on focal length and port type.
• Mounted directly on the lens inside the underwater housing, behind the port glass.

Function and Selection of Recommended Underwater Diopters

Refraction alters focus distance and field of view when light travels through water and glass. A diopter corrects this by shortening the effective focusing distance, restoring image sharpness in supported lens–port setups.

Only install a diopter when specified by the housing manufacturer. This category includes only diopters explicitly recommended by de manufacturerd of hosuings and ports. Many diopters exist, but only those relevant for underwater photography are listed here for precise optical correction.

• Mounted behind the port inside the housing
• Used only when listed as required in port charts
• Correction strengths typically between +2 and +4
• Ensures focus accuracy for specific lens–port combinations
• Only models relevant for underwater photography included