When photographing handheld at slow shutter speeds there is an inherent danger that a certain amount of camera shake will record on film. The degree of shake is dependent upon just how slow the shutter speed is, how long a lens is mounted on the camera, and how steadily the camera is held. Generally, with moderate or short focal length lenses, camera shake becomes a factor at 1/60 or 1/30 second, although some photographers claim that they can handhold without shake at speeds as slow as 1/15 second.
The problem becomes multiplied as focal length increases; as the lens becomes heavier or longer, even the steadiest photographer needs help. As a guideline, follow the reciprocal focal length rule: put a 1/ over the focal length in use, and that's the minimum shutter speed that will usually guarantee a steady picture. For example, if shooting with a 250mm lens, 1/250 second is probably the slowest speed to shoot handheld.
Camera shake is virtually eliminated with the use of a tripod, a three-legged device with camera-mounting platform, and is reduced somewhat with a monopod, a single-legged version. The camera is attached to the tripod or monopod on a platform via a screw that fits the recessed bushing on the bottom plate of the camera. Certain long lenses also have recessed bushings on a ring mount around the lens barrel. The lens mount shifts the weight from the camera body to the often heavier telephoto lens. Quick-release plates attach to both camera and tripod, and allow for mounting and disengaging without having to screw or unscrew the camera from the platform.
Here are some matters to consider when looking for a tripod:
The height of the tripod can be adjusted for different users or points of view. Each leg of the tripod can be extended two or three times the compacted height via a telescoping tube system. Once extended, the legs are made fast by tightening a bolt or snapping closed a swiveled lock. At the base of each leg is a rubber pad, which both protects flooring and carpeting and creates a non-skid contact. On many tripods these pads can be removed and replaced with points, more suited to working in the great outdoors, where it can be secured by literally sticking it into the ground. Match tripod height to your own and to others who might be using the equipment. Make sure that a comfortable viewing height does not require full extension of the legs. This may cause instability and the danger of tipping.
In general, thick-legged tripods are both heavier and more secure, although more expensive pro tripods use lightweight metal to cut down on the weight. When considering a tripod, this weight/security tradeoff must be taken into account. The use of the tripod--for field shooting or in the studio--will often determine which is more important.
Tripod Capability - Camera Size:
The size and weight of the camera will also play a role in this choice; make sure the tripod is designed for the camera at hand. But be aware of the overall weight and what it will mean--trudging through the woods with a very heavy tripod will dampen anyone's enthusiasm for photography before long. If a lightweight tripod is used avoid extending the legs to their maximum height, as this may result in a top-heavy condition, causing the setup to topple with the slightest touch or breeze. Take note of this when buying such a tripod, and be aware that this may reduce its useful extension-length by as much as a third. The top plate, or tripod head must be able to handle the size and weight of the camera. It also should swivel and lock for shooting in both vertical and horizontal positions. Nearly all tripods have this feature, but less lightweight models tend to give less support on the vertical plane.
Very compact tripods, which telescope down to a foot or less for easy carrying, are available in both thin- and thick-legged versions. Their compactness limits their extension length, but they can be useful for working close to the ground or on a table top. They can also be stood up on a car hood or roof, or even on a flat rock for general outdoor work. Their size makes them a constant and unobtrusive part of most every camera bag.
Center Post Extensions:
While the leg extensions are one way to raise and lower the camera level, many tripods also have a center post extensions. This post may be raised with a hand crank located near the tripod "neck" or via a push/pull air-cushion system. Generally, use center post extensions for fine tuning levels--raising them to their maximum height can effect overall stability, particularly with heavier cameras. Once the desired level is attained, with leg and/or center post extensions, always lock-in the adjustments--slippage can be disastrous.
Tripods have either fixed legs (they can only be spread so far) or legs that splay in any number of configurations, even at different extensions. If working indoors a fixed leg model is fine; if shooting on rough terrain a more flexible tripod can be leveled to match any topography, even uphill. Working with a bubble level will help in evening out horizon lines.
Quality tripods allow for interchangeable heads. For example, switching to a so-called panning head allows rotation of the camera with a handle along a horizontal or vertical plane. This is more useful for motion than still pictures, but can be used to "pan" along with a subject as it goes by--great for sports or wildlife--or merely to swing around the scene to find the best composition. A ball head allows rotation to any angle; this ball and socket arrangement also has a threaded camera screw. Ball heads need some getting used to, but in many ways are the most versatile heads, as they allow virtually any camera position.
Monopods, as the name implies, are one-legged camera supports that usually come with a simple threaded screw platform head, although many allow for interchangeable heads as well. A favorite of sports photographers--who often must move quickly to follow the action or avoid it--they are often utilized for working with long telephoto lenses. Monopods are extended by the same telescoping leg system as tripods. Though not as stable as their tri-legged cousins for very long exposures, they do give more stability than handheld shooting in the 1/30 to 1/8 second range. The charm of a monopod is that it takes up very little space and can be used as a substitute for a tripod in many situations.
One small accessory that is a natural mate to a tripod or monopod is a cable release. Available in lengths that range from 6-inches to a few feet, the release allows shutter firing without the need to touch the camera. This comes in handy for long exposures, as it eliminates the danger of accidental camera shake caused by the pressure of the finger as it hits the release button. In fact, lack of a cable release may actually defeat the purpose of a tripod.
A cable release is a long wire inside a cloth or metallic binding; when a plunger on one end of the wire is pressed a pin on the other injects into the threaded shutter release socket to fire the shutter. Some cameras have electronic cable releases, which generate a small charge which sets off the shutter. Radio or remote control releases allow for firing from as far as 200 feet away.
There's no question a tripod is necessary, regardless of the camera format, for macro photography, with long telephoto lenses and for night or low light photography. That's why buying the best tripod one can afford is an excellent investment; an unsteady, unwieldy tripod is next to useless.