There is a subtle difference of opinion between professionals who prefer zoom lenses vs those who prefer prime. Both lenses have their pros and cons and there is really no hard and fast rule that one is better than the other. But we can look into both aspects and make our own judgment over the matter.
Advantages of prime lenses
Prime lenses have less moving parts inside as they don’t need to move around to adjust focal length and focus properly on subjects at varying distances. Usually if you read the specifications there will be less elements and groups. This makes them faster to focus as well as less shaky. Prime lenses are faster compared to zoom lenses because they have wider maximum aperture. Canon’s L series standard prime EF 50mm f/1.2L USM is one example. It has a wide aperture of f/1.2. Comparatively the widest aperture that a zoom lens has is only f/2.8. This is a huge difference and comes handy specially when shooting at low light. One can easily set the lens to shoot at its widest aperture adjust the shutter speed and shoot without a flash. The wide aperture of prime lenses is also extremely handy when one needs to create a soft blur of the background. Additionally prime lenses are comparatively cheaper to build.
Disadvantages of prime lenses
Prime lenses have a fixed focal length. That makes it unsuitable for shooting in situations where you need to make a tighter composition standing at the same place; such as portrait. This is because of their inability to zoom in to get close to the action. Wild life photographers who prefer to carry only a couple of lenses would prefer to at least carry a single zoom lens in order to shoot subjects at varying distances.
Advantages of zoom lenses
A variable focal length is always suitable when shooting subjects at different distances. They are perfect not only for portrait but for photographing wild life, landscape, architecture and even for macro shots. One does not have to change lenses often to accommodate for different shooting needs.
Disadvantages of zoom lenses
Zoom lenses suffer from the lack of a wider aperture. Canon’s zoom lenses, such as the EF 16-35mm f/2.8L II USM, starts at the maximum aperture of only f/2.8 which is an indication of their lack of speed compared to the faster prime lenses. When shooting at longest focal length one would further have to accommodate for the loss of speed as the available aperture will become even smaller. Zoom lenses have more moving parts inside which means they suffer from more lens shake. When buying a zoom lens it is advisable to go for one that has a built-in image stabilization system. This is important if you intend to use the lens and camera for hand held shots primarily. For image stabilization look for the acronym “IS” in Canon’s EF or EF-S lenses. Comparatively look for the acronym “VR” when buying Nikon’s lenses. Zoom lenses are more expensive to build because they have more moving parts and thus the manufacturers have to keep several things in perspective when creating a good optical quality.
It is hard to tell whether zoom lenses are better than prime or the reverse. Different shooting needs require different lenses. A serious photographer will always want to have 2-3 lenses and one being a faster prime as it is easier to lock focus with and faster.