[Gray Angel Fish, Nikonos V with 28 mm lens and SB 103 Speedlight]
Introduction to Underwater Photography
By Paul Janosi
[Tiger Grouper, Nikonos V with 35 mm lens and SB 103 Speedlight]
Choosing an Underwater Camera
The most frequently asked question is what equipment do I need to take underwater pictures. The answer to that question largely depends on what you want to photograph. Close ups of marine life of fish require different equipment than reefscapes or shop wrecks do.
The Nikonos underwater camera system is one of the most versatile systems on the market today. It was designed as an add on system. You can start with an amphibious viewfinder camera with a 35 mm normal lens and get great pictures above or below. A next logical step is purchasing a speed light. As your skill progresses a multitude of lenses, flashes and accessories can be added on. Other lenses available include the 80 mm telephoto lens, 28 mm medium wide angle, 20 mm wide angle and 15 mm super wide angle lenses. There is a close up kit which can be used with the 80, 35 and 28 mm lenses to give magnifications of 1:2.2, 1:4.5 and 1:6 respectively.
There are two speed lights available. The Nikonos SB 103 is ideal for macro or standard lens photography. The more powerful Nikonos SB 102 is ideal for wide angle scenes. The system also has a double sync cord which enables two SB 102 or SB 103 speed lights to be used in TTL automatic flash mode.
Lets start with the basics of using the camera, with either 35 mm or 28 mm lenses and available light.
The Nikonos V with its TTL (through the lens) metering system works as well on land as it does underwater. Actually it has a dual metering system, one for TTL automatic exposure in ambient light, the other for automatic flash exposure. Parallax
The Nikonos is a view finder camera. That is when you look through the eyepiece, you are not seeing exactly what the lens is seeing but rather a view through a small window above the lens. For photography at distances grater than 3 feet the slight difference in view between the viewfinder and lens does not affect the composition. However, as the subject gets closer to the camera lens, the difference tn the field of view (Parallax) can be a problem if you dont take it into account.
Getting sharp, clean images underwater depends on accurately estimating camera to subject distance. This is hindered by refraction, the bending of light rays as they travel through the air/water interface. As a result of refraction objects/subjects appear 25% closer than they actually are. Since the camera lens perceives the object/subject distance the same way the eye does, whatever distance you estimate the subject to be from the camera that is the correct focus setting for the lens. Distances in feet are printed in read and are visible through the front of the lens. Adjust the silver focusing knob to the desired lens distance.
35 mm lens
The first lens most photographers purchase with the camera is the 35 mm standard lens this lens can be used both above and below the surface. It has apertures fro f2.5 to f22 and can be focused from 2.75 feet to infinity. Although the picture angle of the 35 mm lens is 62 degrees on land, underwater due to refraction it is only 44 degrees. That means that the distance of three apparent feet it covers an apparent picture area of about two by three feet. This is excellent for photographing fish, large anemones or a head and shoulder portrait of a diver.
Beginners sometimes get blurred pictures because of the limited depth of field. When set to 4 feet at f5.6 the depth of field extends from 3.5 feet to 5 feet. Depth of field can be increased by using a higher ISO film which allows the use of smaller apertures.
Aiming the 35 mm lens
The built in viewfinder in the Nikonos V was designed for the 35 mm lensens. The frame lines in the viewfinder show about 80% of the true picture area. To ensure that the subject will fill the frame completely move in until the subject appears too close to the frame lines. After seeing the results on the first roll of processed film composition can be fine tuned.
28 mm lens
When the photographer is ready to add the second lens with a wider angle of coverage, the 28 mm medium wide angle lens is most often selected. It has an aperture range of f3.5 to f22, focused to from 2 feet to infinity and has a greater depth of field than the 35 mm lens. When focused to 4 feet at f5.6 the depth of field extends from 3 feet to 5 feet. At f8 from 3 feet to 6 feet. This lens was designed exclusively for underwater use and has and angle of coverage of 59 degrees. At three apparent feet it covers a picture area of 2.5 by 3.75 feet. This allows you to photograph larger subjects with sharper detail. For smaller subjects it focuses to 2 feet as compared to 2.75 feet with the 35 mm lens. This lens is excellent for photographing subjects 2 apparent feet or larger such as barracudas, sharks, dolphins, rays, turtles, octopus or any other sea life that you can not get close to.
Aiming the 28 mm lens
Although the built in camera viewfinder can be used, the composition will be misleading because the picture area will be larger than what is seen. For best results the optical viewfinder designed for use with 20 mm lens should be used. It is supplied with a mask for 28 mm lens. For minimum distance (two feet) there are parallax correction markings on the mask. First compose the desired image in the viewfinder, than tilt the camera until the parallax indicating marks are at the top of the desired image.
Available Light Exposure
Automatic exposure control makes taking pictures underwater surprisingly easy. After film speed information is set into the camera via the ISO film speed dial and the film is loaded, the Nikonos V lets you select the f stop and it automatically picks the shutter speed from 1/30 sec to 1/1000 sec.
For available light photography 100, 200 or 400 ISO film is recommended with the 35 and 28 mm lenses in order to take advantage of the extended depth of field possible with the faster films.
Automatic Exposure Control
When you view your subject through the viewfinder and depress the shutter release partway on auto the exposure display inside the camera viewfinder show the shutter speed chosen by the camera. To prevent blur form camera shake select and aperture setting that will give a shutter speed greater than or equal to 1/60 sec. If the subject is too bright or too dark the arrow shaped led (light emitting diode) will blink indicating over or under exposure. For correct exposure you simply close down or open up the aperture until the blinking stops. The aperture selected is also visible through the front of the lens. They are printed in silver and controlled with the black focusing knob located on the side of the lens. When the aperture is rotated the red indicating arrows above the focus scale will move indicating the depth of field at any distance focused and aperture set.
Manual Exposure Control
For subjects that have too much contrast manual exposure is recommended. Select desired shutter speed such as 1/60, 1/125 or 1/250 sec. Look through the viewfinder of the camera and partly depress shutter release. The shutter speed manually selected will light up and the shutter speed the camera would automatically select for the given f stop will start to blink. Simply adjust the f stop or change the shutter speed until the blinking stops or the desired exposure compensation has been achieved.
Available light photographs will be colourful if they are taken in shallow, clear brightly lit water. The best time of the day for available light pictures is midday from 11 a.m. to 2 p.m. when the sun is directly overhead (maximum light penetration). The position of the sun relative to the subject is important.
Make sure there is separation between the subject and the background. If you want your subject to appear relatively light against a darker background of deep blue water than have the sun behind your back. Position yourself lower than your subject and take a light meter reading on the water behind the subject.
If you want to accentuate the sun rays and the subject to appear dark (a silhouette) then the sun should be positioned in front of the lens and behind the subject. Since sun streaks move rapidly it is best to shoot at 1/125 sec or faster.
The center of the pool of light is always extremely bright, therefore it may fool auto exposure. Use a manual setting and take the exposure reading to one side of the sun. Under most clear water conditions where the surface is visible and you are aiming into the sun your exposure will guarantee that at least one of the images will be perfectly exposed.