Why I Love the 50mm
For years, many photographers shot with almost exclusively with their trusty 50mm. The reason for this is the image quality combined with overall versatility of this focal length. It is often said that the 50mm perspective on 35mm film/digital closely mimics what the human eye sees.
Henri Cartier-Bresson, one of the greatest photojournalists of this century and certainly one of the photographers to raise photojournalism to the level of high art, reputedly used only the 50mm lens for everything from landscapes to portraiture (though he did use others as well.) Here are a couple of reasons why you should love your 50mm.
The 50mm lens delivers images that appear most natural to what the human eye sees when we look at a scene. This is why they are also called, "normal lenses." Wider lenses tend to distort perception. For example, when shooting portraits with a 28mm lens body parts may look humorously larger than in real-life. In contrast, longer lenses offer a much flatter perspective. This is why they are often preffered for portraits. When a person looks at your images shot with a 50mm lens, they will be viewing something that simulates what they actually would see if they were there. This is why they are so popular with photojournalists and documentary photographers. The perspective is also coupled with the fact that the images can be given more depth by stopping down the aperture or singling out a specific subject by opening it up.
For clarification, this is only for full frame (35mm) camera users like the Canon 5D Mk II, Nikon D700 or Sony A900. On an APS-C sized sensor, the lens is longer (either a 75mm or 80mm field of view is displayed in the viewfinder).
Small Size and Light Weight
In general 50mm lenses are small and fairly light. These lenses are typically between f/2.8 and f/1.4. Once the lenses start having larger apertures they become heavier and larger. Famous examples are the Canon 50mm F/1.2, Leica 50mm f/0.95 Noctilux and others.
Photographers that don't want to be a host to back, neck and shoulder problems will be alleviated by the fact that 50mm lenses are lighter than your 70-200mm F/2.8 or your 24-70mm F/2.8. The lighter weight coupled with the focal length's perspective will also encourage many photographers to keep the lens on their camera because of the versatility—more on this later.
50mm lenses will also take up less space in your camera bag. Even if you aren't lugging a camera bag around, a 50mm lens can be screwed onto your DSLR and taken with you nearly anywhere. Indeed, I used to carry my 5D Mk II and 50mm F/1.8 everywhere. The combination fit easily into a messengar bag with a laptop, flash and extra lens just in case. Finally, some subjects may feel intimidated by longer lenses. This is also one of the reasons why 50mm lenses are so popular with street photography. I have yet to encounter anyone that has faced this problem with a 50mm lens.
Low Light Abilities
In general, prime lenses are known for having larger apertures than zoom lenses. The 50mm lens is no exception. Because of the larger aperture, your camera will be able to capture more balanced photos in low light at lower ISO speeds.
The list can go on and on of the types of photographers that would find the low light abilities invaluable: wedding photographers, photojournalists, concert photographers, documentary photographers, indie cinematographers, event photographers, landscape photographers, street photographers, etc.
Many budding photographers using a 50mm lens usually shoot with it wide open almost exclusively. In photography, this is known as, "The Bokeh Effect" and comes from the fact that the photographer is obsessed with the fact that they can focus on one subject and have everything else out-of-focus in the creamy background. It is a growing pain and users soon realize that the lens becomes significantly sharper when stopped down to around F/4-F/5.6; more on this later on. This typically regulates the wide open shooting to lower light situations; such as a wedding ceremony where flash is not allowed.
As a note to these users, be careful how your lens is focusing. Focusing issues can occur where your camera and lens combination is not actually focusing on the spot where you inteded. To check for this, bring your images into your favorite viewing software and view the spot focused on at 100%.
Image Quality of a Prime Lens
Besides being faster, prime lenses are also known to have exceptional image quality when stopped down (the exception being Leicas which are designed to be sharp at every single aperture and reflect it in their price.) The reason being that prime lenses are easier to manufacture. Because the lens only has to be sharp at one focal length, the optical construction is much simpler. Look at diagrams for the way any lens is constructed and you'll see just how complicated zooms can be. To boot, they are also much more affordable than zoom lenses. To get the image qualtiy of the best prime lenses in a zoom lens, one usually ends up forking over the equivalent of two month's rent or more. Manufacturers also realize just how important 50mm lenses are to photographers, and so they put out different versions to cater to different needs.
Modern zoom lenses have been making quite the splash though as they are becoming more versatile and meet the needs and demands on most working photographers these days. Generally prime lenses are still sharper and can deliver better results. Many photographers prefer to choose prime lenses over zooms as it helps them to compose better images. The 50mm is no excpetion.
The Digital Picture has a lens comparison tool for potential buyers to compare and contrast the sharpness and qualities of various lenses.
Versatility as an Everything Lens
The 50mm lens is extremely versatile and can be used for a variety of situations. A 50mm lens can help a photojournalist create an environmental portrait for a special feature story. Similarly, they can use it to single out important detail shots such as the hands of a very hard worker accomplishing a daily task. It is highly recommended as a wedding reception lens for photographers that do not want a 24-70mm F/2.8. Indeed, F/2.8 is even sometimes too slow an aperture for some concerts I've shot since there wasn't enough light.
Almost any situation that you can name can be shot with a 50mm lens. While it may also become your precious child of a lens, also once again remember how affordable they tend to be. Also coupled with the portable nature, they add so much more convenience to a photographer's tasks. Just remember that you'll need to zoom with your feet to change your perspective.
Challenge yourself to shoot with a 50mm lens exclusively for a day, month or a year and see what you come up with. Many photographers and students that have done this state a noticeable change in their photography habits.