Properties of Water which effect Underwater Photography. On this planet of water, the natural elements of air, water and minerals cause certain effects which divers become aware of once they descend below the surface. Magnification is a result of refraction of light energy waves which can be seen if one would place a pencil in a glass of water. This is the result of these energy waves being bent as it passes from one medium to another. Examples are sunlight entering the atmosphere being bent like a prism. Where some are reflected and results in a blue sky. Then as these energy waves enter water, which is denser than air, the sunlight gets refracted again. Once reflected off a subject it then passes the glass of a mask and is bent again. Resulting in an increase of 25% in how close and how larger objects appear underwater. Another way of saying this, objects that are four feet away, will appear three feet. For the photographer the way objects appear is the same as how distance is set on the lens. Another effect of refraction is that the energy waves start to be consumed by water molecules, plankton, and algae as the depth of the water increase. It begins at the red end of the color spectrum, and as one descends to ninety feet the remaining colors are blue gray and black. This is why diver uses under water light to restore the light rays lost and uses a strobe to flash the subject and area with a comparable flash of light like sunlight. Learning the balance of flash and ambient sunlight take practice, practice, practice. Discussions on the blending of light sources are under the strobes article. Turbidity can also cause problems underwater while trying to capture a reef scene. This can be from movement of water or from high dissolved minerals, or high plankton suspended in the water. This results in light waves having to bend around the matter and distorts the received reflection of an image as seen underwater. Parallaxing is how a diver will see a subject on one plan of perspective and the camera lens will see the image on a different plan of view. Learning to keep the lens of the camera and a divers mask on a parallel plan and keeping the camera close to the eyes is the best way to obtain pictures with a range finder type camera system. The through the viewer single reflection lens (SRL) allows a diver to look via a mirror through the viewer and see the actual composition as composed. This eliminates parallaxing if a magnifier is placed on the small viewfinder. Some cameras are designed with larger windows to see through such as the Nikonus RS System. Others have grids or guide lines on the viewers to help compensate for distance such as the Nikonus range finder camera. Housed cameras have an attachment for the viewer which can magnify the SRL image, however you need to keep it close where distortion of seeing the presumed picture at a slight angle. Practicing to keep the subject matter at three feet away from the lens and keeping the viewer close to the eye where the image seen will be the same in print. If images are not in the same quadrant as you visualized or a fish, diver and other subjects get cut off the picture, then you know parallaxing has occurred. Remember Underwater Photography starts as skill development, then composition followed by technique and finely artistic realization.