D-SLR: Digital Single Lens Reflex. Digital Single Lens Reflex. A digital camera that utilizes SLR technology. (See SLR)
EF: Electro Focus. Lens mount utilizing the bayonet style mount system to mount the lens to your camera. Focusing with EF lenses is handled via electronic motor housed within the lens itself. All information received by the lens is sent through to the camera via electronic contacts. The EF lens mount is the successor to the FD mount.
FD: Canon has not released a specific definition for the acronym FD. The FD mount is the predecessor to the EF mount. The FD mount utilizes the breech lock lens mount system and was created based upon the need to create a more accurate lens that allowed for less friction between lens and camera when removing and installing lenses. The FD lens mount is the successor to the FL mount.
Fisheye Lens: Fisheye Lenses have a very wide range of view (upwards of 180 degrees), more so than a standard wide angle lens. As such these lenses tend to give images a "barrel effect" or round distortion.
Focal Length: The measure of distance from the surface of your camera's lens to your subject or target of focus.
L Lens: Canon L lenses are Canon's high end, luxury line of lenses
Macro Lens: Macro lenses are fixed focal length lenses that allow a user to focus from infinity to very, very close using a short focal range. These lenses are typically used to capture very small objects.
Prime Lens: Prime lenses are usually fixed at one focal length and cannot magnify an object alone as a zoom lens can. Another type of prime lens would be a primary lens in a combination lens system.
SLR: Single Lens Reflex. A single lens reflex (SLR) camera takes photos by retracting a mirror when the shutter is released. Light coming into the lens is reflected onto either a ground glass screen (also known as viewing screen) above the mirror.
Telephoto Lens: Telephoto lenses use a fixed focal length unlike a zoom lens, but can bring objects at a distance into focus for framing purposes. The name is uses the same root as telescope and is similar in functionality.
Wide Angle Lens: Wide angle lenses have the opposite effect of a telephoto lens whereas you can effectively push an object further out as opposed to pulling the object closer to you. These lenses are great for indoor photography and confined spaces.
Zoom Lens: Zoom lenses can bring objects that are at a distance into focus via a series of mechanical lens elements. These elements in unison allow the user of the lens to apply variable focal lengths.