Digital Only vs Full Frames Lenses:
Just like camera bodies, camera lenses come designed for full-frame, APS-C-sized, or Four-Thirds-sized sensors. It is important to understand this distinction to ensure compatibility between lenses and a camera.

A full-frame sensor is generally 1.5x the size of an APS-C-sized sensor and 2x the size of Four Thirds-sized sensors. For the most part, cameras with APS-C- sized sensors can use both digital-only and full-frame lenses. However, some full-frame cameras (notably Canons) can use ONLY full-frame lenses.

When using a full-frame lens on a smaller-sized sensor it is important to remember that the field of view of the lens changes because the sensor is not utilizing the entirety of the lens’ coverage. Because full-frame sensors are about 1.5-1.6x times the size of digital sensors, multiply a full-frame lens’ focal length by 1.5 to determine the equivalent focal length on a digital-only camera. For example, if you were using a APS-C-sized sensor camera with a full-frame 17-35mm lens on it, the restricted field of view of the lens would make it equivalent to about 25.5mm-52.5mm on the full-framer.

If you are investing in camera equipment, but can afford only an APS-C-sized sensor camera, it may behoove you to purchase some full-frame lenses so that down the road, they will work with newer full-frame equipment you may get.

Prime Vs Zoom Lenses:
Prime lenses are only one focal length, such as 24mm or 50mm. Because these lenses have fewer moving parts, and are often less-complicated optical designs, they can be considerably smaller than zoom lenses. They also often have a wider maximum aperture (a lower f-number), which allows the lens to admit more light.

Zoom lenses, on the other hand are capable of a range of focal lengths, such as 17-35mm, or 70-200mm. Because of this range, these lenses can be more versatile than prime lenses, but are often larger, and are almost always “slower”—that is, they admit less light because of smaller maximum apertures.

Super Wide and Wide-Angle Lenses:
The super wide-angle lens category generally refers to lenses that have a focal length between 8-14mm (digital-only) or 12-20mm (full-frame), while the wide-angle category generally refers to lenses that have a focal length between 14-24mm (digital-only) or 20-35mm (full-frame). The price for lenses in both of these categories can vary widely, depending on the quality of the glass and the maximum apertures. A lens that has a contant f-stop of f/2.8 will be far more expensive than a similar lens that has a lowest f-number of f/3.5-5.6 across its zoom range.

These lenses are great for candid photography and photojournalism, concert photography and architectural photography. They allow one to be very close to a subject and still capture a large slice of the scene. At shorter focal lengths, these lenses can and will distort an image, usually barreling it outward from the center.

Normal Lenses:
The original normal lens was a prime—50mm on a full-frame camera. Today many kit lenses are referred to as normal zoom lenses. They generally feature a focal length of around 18-55mm (digital-only) or 24-80mm (full-frame).

Like wide and super wide-angle lenses, these lenses can really vary in price—but they are often more affordable than super wide/wide angle lenses and telephoto lenses partly because they may use smaller glass elements and, sometimes, fewer moving parts.

These lenses are a wonderful choice for shooting in just about any situation, hence their name. They are great for portrait, candid, travel, close-up, and sports photography.

Telephoto, Super Telephoto and Super-Zoom Lenses:
Telephoto lenses generally have a focal length of between 70-300mm for either digital-only or full-frame formats, while Super Telephoto lenses generally refers to lenses with focal lengths greater than 300mm. Super-Zoom Lenses are lenses that can start in the Wide-Angle or Normal range and generally go up to the Super Telephoto range of 300mm or greater.

These lenses vary greatly in price depending on their focal-length range, widest aperture, and quality of the glass. The high-end versions of these lenses are often some of the most expensive glassware out there because of the size of their glass elements and optical complexity.

These lenses are great for shooting sports, wildlife, and nature. Super-Zoom Lenses in particular are quite versatile and great for travel and casual photography.