Choosing DSLR Lenses

CHOOSING THE RIGHT LENS

The golden rule of underwater photography is to get as close as possible to the subject to reduce the degrading effects of water. With that in mind it is important to use a lens that allows you to fill the frame with a pleasing composition, working within a few feet if possible.

Ideally you should use a prime (non-zoom) wide angle lens for large subjects or scenic panoramas, macro lenses for extreme closeups, and telephoto lenses for small skittish critters. A zoom lens allows you to switch from wide to telephoto while underwater but image quality & low-light performance may not be as good as a prime lens.

Point & Shoot cameras can take advantage of accessory wet lenses for macro and wide angle. Epoque makes universal adapter rings, lenses, and trays.

If you intend to buy a full-frame DSLR at some point you cannot use any lenses designated as 'digital-only'. Most affordable DSLR's are APS-C format, a cropped sensor 40 percent smaller than traditional 35 x 24mm film. Full-frame lenses will work on both types while APS-C-only models will only work on those bodies. One must also recognize that the angle of view for a full-frame lens is decreased by roughly 40 percent when used on an APS-C camera.

Macro lenses are best used with flat lens ports and wide angle lenses & zooms are used with dome ports as the dome preserves the angle of view. Zoom lenses must be able to focus to about 12 inches or a closeup filter will have to be attached to work properly underwater. Note that the closeup lens will make it impossible to focus above water and reduce image quality to some extent.

EPOQUE WET LENSES

Yuko switching from macro to wide angle lens

Epoque Wide Angle Lens on Canon G9

Epoque 2X Macro Lens, same dive

FISHEYE LENSES

	Sigma 15mm Fisheye

WIDE ANGLE LENSES

	24mm f/2.8
	5 feet from subject
	3.5 feet from subject
	2 feet from subject
	1.5 feet from subject

STANDARD MACRO LENSES

	50mm f/2.8 Macro
	3 feet from subject
	1 foot from subject
	6 inches from subject

Good for working close to subjects in murky water and for medium-sized subjects with clear water. Most models are designed to produce 1:1 or life-size magnification with a working distance of a couple of inches. These are among the sharpest of lenses. When focusing very close, this focal length makes lighting the subject difficult without creating strong shadows. Not good for skittish subjects.

TELEPHOTO MACRO LENSES

	90mm 1:2 Macro
	1.5 feet from subject
	2.5 feet from subject
	14 inches from subject 1:2

The ideal lens for small and medium sized subjects, namely tropical fish, portraits, and most closeup work. The narrow field of view and minimum working distance of nearly 1 foot allow better frontal lighting and the ability to work with subjects that may be somewhat skittish.

Today most lenses in this category will produce 1:1 or life-size macro magnifications. Somewhat greater magnification can be achieved by attaching a closeup diopter to the filter threads or to the outside of the lens port underwater without losing autofocus capability.

ZOOM LENSES

	28-70mm f/3.5 - 5.6 +4 closeup lens

	70mm zoom @ 2 feet
	28mm zoom @ 4 feet

Good for situations where one cannot decide between a wide angle and short telephoto lens. In most cases a +3 or +4 closeup lens will need to be attached to the filter threads when used with a dome port to enable focusing underwater. Check the housing/port instruction manual. Unfortunately this configuration will prevent it from focusing to infinity above water.

Since most zoom lenses small enough to fit underwater housings have minimum apertures of f/3.5, the viewfinder image is darker than with most 'prime' lenses. Rotating the zoom knob can be a nuisance. Zoom lenses are also not as sharp as prime lenses. If you are on a budget, you'll probably get the standard zoom lens and body as a kit.

TELECONVERTERS

2x Teleconverter Doubles focal length/magnification of any lens	2x Teleconverter stacked on 90mm 1:2 Macro Equivalent to 180mm 1:1 Macro Retains full-range autofocus
1 foot from subject	1.5 feet from subject
8 inches from subject with closeup lens on port	1.5 feet from subject

Ideal for situations where the subject is small and/or difficult to approach. Best used with a 100mm f/2.8 macro lens, especially one that only produces 1:2 maximum magnification to maintain AF function. Ideal working distance is about 15 inches from the lens port. Due to the extremely narrow field of view, it is very difficult to follow moving subjects and contend with water motion.

Due to the amount of glass involved, sharpness and resolution will be less than perfect depending upon the aperture selected. A 2x converter reduces the amount of light received by two f/stops resulting in a darker viewfinder image.

Adding a closeup lens to the front of the port allows the system to focus within 8 inches. Sharpness is reduced at the edges but magnification greater than 1:1 is possible.