The Ikelite 6441.71 Green Water Filter is a push-on, color-correction filter that is designed for use with Ikelite underwater camera housings with 2.2" short ports.
High concentrations of chlorophyll-containing phytoplankton within a body of fresh or salt water can absorb and scatter sunlight entering from above. This can cause the water to appear green and obscure the colors of objects as well as fish, coral, or other underwater life within it. Due to its density, water alone naturally attenuates radiation, including visible light. Lower-energy wavelengths of visible light that are apparent as red, orange, and yellow colors are attenuated more than higher-energy wavelengths of visible light that are apparent as blue, indigo, and violet colors. This further obscures the ability to see red to yellow hues, and can otherwise limit underwater life or objects to appearing only in shades of blue to violet.
To help balance the levels of visible light while photographing in green-colored fresh or salt water, the Ikelite 6441.71 Green Water Filter suppresses ambient green, blue, indigo, and violet light while allowing available red, orange, and yellow colors into an underwater housing and camera. This filter is most effective while under bright sunlight from directly overhead, and under those conditions is useful for subjects that are up to 80' away. When an image is taken underneath green water using the Ikelite 6441.71 Green Water Filter, elements within the frame that are progressively closer to the camera and have red, orange, and yellow hues will show a corresponding increase in color accuracy. This is due to the decreased distance needed for the wavelengths of visible light responsible for those colors to reach the camera, which reduces their risk of being absorbed by the surrounding water.
This filter is constructed from optical plastic for clarity, with a front anti-scratch coating and features a durable rubber ring that maintains a reliable grip on a compatible port. To prevent loss when not in use, a nylon lanyard is also included so that the Ikelite 6441.71 Green Water Filter can be slipped over the wrist or fastened to a separate retaining device. Should itself or an attached filter become entangled with a fixed underwater object, the lanyard's break-away design allows the user to easily separate themselves from it.