Camera Lenses - Introduction to the Different Types of Lenses, From Zoom to Pancake
One of the best features of Mirrorless Cameras is their Interchangeable Lens feature. In normal compact cameras, lens is part of the camera's body and, although it can offer different degrees of zoom, its performances are fairly limited. In a Mirrorless Camera you can remove the lens and replace them with another one which better suits your needs in different occasions: detailed close-ups, panoramic views or super-zoom are some of the many options available. If you already have lenses that you'd like to reuse, there's a great news: with the right adapter, you can mount almost any lens on your new Mirrorless Camera. If it's a model adopting the micro 4:3 standard (like the Panasonic DMC-G1, for example), then you could reuse every 4:3 lens you already have. It's a huge advantage! If you're not familiar with the world of photography and its lingo, please read the following introduction on lenses, it will help you getting a grasp of the most common terminology and concepts.
Focal Length
The first feature you should check in a lens is called Focal Length. The following are its key concepts:
Focal Lengths are indicated in millimeters (mm)
Some lenses have one focal length, thus they are called Fixed Focal Length or Prime lenses. As the name implies, these lenses' Focal Length cannot be adjusted. They are usually found on cheap cameras.
The majority of lenses covers a range of Focal Lengths. These models are called Zoom Lenses.
The smaller the Focal Length number, the wider is the angle of the view captured by the lens. These lenses are therefore suitable for panoramas.
The greater the Focal Length number, the higher is the zoom and, consequently, the smaller is the part of the scene captured by the lens. These lenses are suitable for Telephoto (Zoom) pictures. For example, the big lenses you can see in the hand of photographers on football fields have a very high Focal Length, enabling them to take a picture of distant subject, such as the players on the other side of the pitch.
Here are some examples of different lens Focal Lengths:
35mm
A Fixed (or Prime) lens with a moderate Telephoto view.
14-45mm
A Zoom lens with a range from Wide Angle (14mm) to a moderate Telephoto View (45mm).
50-150mm
A Zoom lens focusing on Telephoto, from moderate to high (hence unsuitable for wide angle pictures)
Mirrorless Cameras are normally sold with what is called a "kit lens". This lens is a general purpose Zoom, and it's suitable for taking Wide Angle and moderate Telephoto pictures. If you use your camera for recreational purposes, such as taking pictures of your vacations, this kit is all you'll need. Should you decide, instead, to go for a Safari, where you will need to photograph far away subjects, then it will be worth investing in a Telephoto lens with a longer Focal Lens.
Maximum Aperture
The aperture of lens is a measurement of how wide the lens can open. The unit used to express it is called "F-Stops". The higher the value, the smaller the Aperture (i.e. an Aperture of f/2.8 is wider than a f/5.6). A lens with a wider Aperture lets more light in and results in faster shutter speeds. It also performs better in conditions of low light (e.g. evening or night), allowing to capture images that would simply be too dark with a small Aperture. All lenses, with few exceptions, can be set to the same narrow Aperture. However, not all of them can be set to the same wide one. Another important fact is that some lenses have only one Maximum Aperture, while others have two. This type of lens is called Variable Maximum Aperture Lens. Only Zoom lenses can have Variable Maximum Apertures, and it's directly related to their Focal Length. The longer the Focal Length, the narrower the Maximum Aperture. Let's take, for example, a lens with a Focal Length of 14-42mm and a Maximum Aperture of f/3.5-5.6:
At 14mm (Wide Angle) the lens can be set to a Maximum Aperture of f/3.5
At 42mm (Telephoto) the Maximum Aperture becomes f/5.6
Pancake Lens
Mirrorless Cameras can also mount a special type of lens called Pancake Lens. This somewhat funny term derives from the fact that these lenses are very thing (like a pancake). The main advantage of a Pancake Lens is the portability; being so small they don't add a lot of size and weight to the small volume of a Mirrorless Cameras. The major drawback of this type of lenses is their lack of zoom. Pancake Lenses are all Prime, i.e. they have only one focal length. If you need to get a close shot to a subject, they only way to do it is by moving closer, there's no possibility of zooming. This can be a significant limitation, but it's a matter of choosing between flexibility and portability.
