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While wearing a flat scuba mask or goggles, objects underwater will appear 33% bigger (34% bigger in salt water) or 25% closer than they actually are. [2] Also pincushion distortion and lateral chromatic aberration are noticeable. Double-dome masks restore natural sized underwater vision and field of view, with certain limitations. [2] [9]
A diver in a pool wearing an AGA full face mask A diver wearing an Ocean Reef full face mask Head protection helmet for use with Ocean Reef full face diving mask. A full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece, demand valve or constant flow gas supply that provides the diver with breathing gas. [1]
A diving mask (also half mask, dive mask or scuba mask) is an item of diving equipment that allows underwater divers, including scuba divers, free-divers, and snorkelers, to see clearly underwater. [ 1 ] [ 2 ] Surface supplied divers usually use a full face mask or diving helmet , but in some systems the half mask may be used. [ 2 ]
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Snell's window (also called Snell's circle [1] or optical man-hole [2]) is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees. [3] This phenomenon is caused by refraction of light entering water, and is governed by Snell's Law. [4]
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In a few models of full face mask a mouthpiece like those used on diving regulators is fitted, which has the same function as an oro-nasal mask, but can further reduce the volume of the external dead space, at the cost of forcing mouth-breathing. A smaller volume around the mouth increases distortion of speech.
These may be worn with a full-face mask or half mask to provide impact protection when diving under an overhead, and may also be used to mount lights and video cameras. [3] [4] An alternative to the diving helmet that allows communication with the surface is the full-face diving mask. These cover most of the diver's face, specifically including ...