So now that you know what a camera let’s get down to business, the next most important part of the camera is the lens. This is what focuses the light into the camera body and onto the medium capturing that light. Lenses can be at the very top broken down into two categories, those are prime and zoom.
A Prime lens is one with a fixed focal length, such as 50mm, 105mm, 200mm.
A Zoom lens has a variable focal length, such as 18-55mm, 70-200mm, 17-35mm.
A lenses focal length is usually measured in milimeters (mm) but you will often find some marked in centimeters (cm), 1cm = 10mm, therefore if you have a 5cm lens, it’s just a different way of saying 50mm.
Another note before going into the different types of lenses, on focal lengthes. Depending on the size of the recording media, the focal length varies. On Digital cameras that us a crop sensor, (smaller than 35mm) there’s a crop factor. You will find crop sensors in SLRs, Point & Shoot, EVIL, and Rangefinder camera types. You can multiply the focal length by that number, so for example on Nikon’s sensor there’s a 1.5x factor, so your 50mm lens will give you the equivilant image of a 75mm lens. To get over this factor to some extent most camera and lens manfactures have released lenses designed for cropped sensors. Now you can use lenses designed for Full Frame (35mm) sensors on crop sensor bodies, but you will be unable to use crop sensor lenses on full frame cameras. (Well you can, but there will be…issues). The focal length also changes the larger the sensor gets, for here you divide the lens’ displayed focal length.
From here lenses can be broken down further into categories based on that focal length.
An ultra-wide or just wide lens is anything with a focal length of less than but not including 35mm. But they keep the straight lines in the image straight (within reason, most ultra-wide lenses produce some level of distortion). This type of lens is great for capturing buildings, and landscapes. However I would avoid using them in portraits, unless you’re going for that look. You can find ultra-wide lenses in both zoom and prime types. Ultra-wides should not be confused with fish-eye lenses. Fish-eyes althougth they fall into the ultra-wide category by focal length, they often have a field of view of 180 degrees and have a very distorted look to them.
The Normal focal range covers 35mm to 70mm, however most people will call a 50mm lens normal as it shares the same field of view as your eyes do. These types of lenses often are great for a carry around fixed focus lens or a simple everyday zoom lens. Most dSLRs ship with a basic “kit” with covers a wide angle through normal usually. The trusty 18-55mm. On crop sensor cameras, a 50mm will turn into the equivilant of a short telephoto (75mm) so I often will use a 35mm lens to get the 50mm (52mm) focal length back. These lenses are great for capturing details and making a great portrait lens. You can get a 50mm f/1.8 (don’t worry, we’ll cover the f number later), for around one hundred dollars these days which make it useful for low light situations and a quick portrait lens. Normal lenses can be found in both zoom and prime, although I prefer them in prime form. Normal lenses especally the the 50mm makes a great portrait lens in a pinch.
A telephoto lens is any lens that is greater than 70mm in focal length. These often are big, heavy, noticable, and unweildly. Avalible in both zoom and prime types. They’re great for portrait work, and event photography, and more importantly sports and wildlife photography. When it comes to arcitecture they’re great for capturing details of a structure that are far away from you. Such as carved figures or other details on skyscrapers and churches. I primarly use telephotos for portrait work and some street photography.
These are lenses that may fit into the above categories but operate slightly differently from a traditional lens.
Selective Focus – These often will blur out the rest of the frame, allowing the person to isolate their exact subject in the frame. The Lensbaby series are famous for these types of lenses.
Tilt-Shift (TS) or Perspective Control (PC) – very specalized lens, often used in arcticture shots because you can actually move the lens elements to make lines straight. So in a building where to capture it all you’d have to tilt you camera up, the building would have diaganol lines converging at the top. With a TS/PC lens you won’t have that issue, you just shift the lens up to frame it as you like.
Macro – Macro lenses are special in the sense they have the ablity to focus really close on an object to show incredable detail. They’re usually in the normal to telephoto range of lenses.