Auxiliary/Conversion Camera Lenses
A dedicated flash, additional battery, camera bag and extra memory card may be the obvious accessories to buy for your camera, but the list of useful add-ons does not end there. Conversion camera lenses widen your horizons and allow you to take better photos. The auxiliary lenses attach to a screw or bayonet mount around the camera's lens or, in the case of extension tubes and teleconverters, between the lens and the camera. By and large, there are four main categories of auxiliary lenses that enhance your photographic skills.SLR Teleconverters
The SLR teleconverters allow your magnificent telephoto lenses reach even further. The converters fit between the camera and the lens. The number next to the lens indicates how much closer it brings the objects. For example, a 1.4x converter extends the focal length by 140 percent. You do lose some light when using the converter, but it is worth the trouble if you want to capture wild animals or some other objects that are far from you and that you could not get closer to physically.SLR Extension Tubes
The single-lens reflex extension tubes add close-focusing capability to SLR lenses. They add some distance between the camera's sensor and the rear end of the lens. This means the lens can focus much closer, but when the extension tube attaches, you actually cannot focus on faraway objects. You can achieve best results with the extension tubes when using a digital SLR.Macro and Telephoto Adapters
A telephoto adapter allows you to reach further, bringing distant objects closer. The number next to the telephoto adapter indicates how much closer the object is. On the other hand, macro lenses improve your camera's ability to capture objects that are extremely close.Fisheye and Wide-Angle Adapters
Fisheye camera lenses create the fisheye effect, allowing you to take unique photos with an exaggerated depth of field. The higher the number next to the fisheye lens, the subtler the effect. For instance, a 0.40x fisheye adapter lens creates a more modest fisheye effect than a 0.18x fisheye adapter. Wide-angle camera lenses expand your field of view. The magnification factor determines how much wider the field gets once you adapt the lens. For example, attaching a 0.5x adapter to a 50 mm lens results in a field of view equal to that of a 25 mm lens.