Finding the Right Lens Port for Your Underwater Casing
If you are interested in underwater photography, it can be very confusing to pick the correct lens port. Typically, underwater camera housings from all manufacturers have interchangeable lens ports. The two most common types of lens ports are flat ports and dome ports.
The air-water boundary causes flat ports to work as a lens. The main function of a flat port is to reduce the angle of coverage and increase the magnification of the main camera lens. Flat ports are often called macro ports because the extra magnification comes in very handy if you are using a macro lens. Flat ports should not be used in conjunction with a wide angle lens, because these ports have a tendency to cut off the picture at the corners.
The purpose of a dome port is to correct the reduction in angle of coverage that is caused by the air-water boundary of the camera and underwater camera housing. By placing the dome port over a wide angle lens, no refraction will occur when light heads for the entrance pupil, which conserves the angle of coverage that is provided by a wide angle lens. If you are using a dome lens with a standard lens, you will need to add a close-up lens, as well.Popular Lenses: