Prime Lens 101
The major benefit of upgrading to a DSLR or mirrorless camera system is the ability to swap out different lenses to fit your specific needs. Prime lenses are available in all lengths and varieties and offer numerous advantages in performance when compared to their zoom-lens brethren. Also, the particular choices associated with sticking to a specific focal length can help improve your photographic technique, as well as help you learn. And, a new prime lens can expand your capabilities with new features like a larger aperture for more effective low-light shooting or a specialized feature that enables you to get the close-ups you’ve always dreamed about.
Prime versus Zoom
Zoom lenses are incredibly convenient. They cover a wide range of focal lengths in a single package, and you don’t have to waste time constantly swapping out lenses to create the composition you desire. However, this huge strength also becomes their weakness. Designing a lens for optimal performance at multiple focal lengths is difficult, meaning that there will be some trade-offs in performance and size. Not to say there aren’t good zooms—there are—but they usually come with a premium price tag.
On the other hand, prime lenses are optimized to a specific focal length or purpose. This means that optical performance is generally much better and that the lenses can be made with larger apertures while still maintaining a fairly compact size. Another benefit is that a prime lens will have fewer moving parts, so there is less of an opportunity for problems to appear from general use. Generally, primes perform better than their zoom counterparts and are sharper, with fewer visible aberrations. These differences can be very apparent, especially with the high-resolution sensors currently available in modern DSLR and mirrorless cameras.
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Another major difference is the inability to zoom for changes in composition. This requires a photographer to be more thoughtful in their process and to move around a bit more since they can’t rely on a zoom lens to change perspective. This makes choosing a focal length one of the most important decisions when considering a prime lens.
Choosing a Focal Length
Different focal lengths are better suited to certain subjects or styles; this is why you will constantly see lenses like the 85mm referred to as a “portrait” lens, or the 35mm as a “street” lens. This has a lot to do with field of view and what you need the lens to do. Capturing cramped interiors will be the domain of the wide or extreme wide-angle lens, whereas distant wildlife or sports will obviously require the use of a telephoto lens.
Besides the obvious, different focal lengths have their own attributes and looks. For example, the longer the lens is, the shallower the depth of field will be, when they are compared at the same aperture setting. A 100mm lens at f/2.8 will have much shallower depth of field than a 35mm at f/2.8. Also, telephoto lenses tend to flatten features and compress space, making the background elements appear much closer and larger than a wide-angle lens would. This is why an 85mm is a popular choice for portraiture; it has good background separation due to shallow depth of field, and will flatten a subject’s features slightly for a more flattering image. Wide angles will exaggerate perspective, and will make subjects appear distorted, but they can capture a larger area and are well-suited to architecture, landscapes, and other types of photography where dramatized elements are wanted.
Keep in mind that sensor size will affect the effective angle of view captured and that lenses are commonly given a 35mm equivalent focal length for use with different formats, such as a DSLR with an APS-C sensor. A 50mm lens mounted on such a camera, with a 1.5x crop factor, for example, will have an equivalent focal length of 75mm. This doesn’t mean that the specific qualities of the lens have changed, a 50mm is still a 50mm, just that the area captured is similar to that of a 75mm lens on a full-frame camera, as if you had cropped the image in post to capture the same angle of view.
A benefit of this is that users can enjoy more reach from their longer lenses. This can convert already far-reaching options to have longer equivalent focal lengths that may not be available otherwise. For example, Nikon’s AF-S Nikkor 600mm f/4 ED VR AF lens or Canon’s EF 600mm f/4 IS II USM become equivalent 900mm and 960mm lenses respectively, which is longer than either company’s current longest lens at 800mm.
Some manufacturers take the popularity of crop-sensor cameras into account when making lenses. This means that some prime lenses work properly only on APS-C or smaller sensors and will not provide full coverage when using a full-frame camera. This does allow lenses to be much smaller than they would need to be or to achieve equivalent focal lengths that are desired. Fujifilm does this with their APS-C mirrorless camera series by releasing 23mm, 35mm, and 56mm lenses, which are equivalent to the popular, 35mm, 50mm, and 85mm lenses on full-frame cameras.
If you do own a crop-sensor camera and your brand offers full-frame options, you should consider whether you would like to eventually upgrade to the larger sensor later on. If you do, crop-sensor lenses will not work on your later camera, though full-frame lenses will work properly on crop-sensor cameras. Purchasing full-frame-compatible glass now can save you time and money later.
There are other features, such as maximum aperture, minimum focus distance, and autofocus motors, which will play a huge role in any final lens choice, but focal length will remain the most important.
One of the most common options is the standard or normal lens. These lenses have an angle of view close to 45°, which replicates the perspective seen by our eyes. This makes it a good first lens for beginners because it is easy to imagine what images will look like before you even put the viewfinder up to your eye. In 35mm terms, these lenses fall between 40mm and 65mm, though the 50mm is the most popular and well-known option.
Many prominent photographers have claimed this as their favorite lens, such as Henri Cartier-Bresson, one of the most important photojournalists of the Twentieth Century, and an icon for amateur and professional street photographers. He famously used a 50mm lens almost exclusively as it acts as “an extension of (the) eye,” permitting photographers to trap life in a frame that resembles the way we experience the world.
Normal primes are also well liked because they are easy to manufacture, inexpensive, and usually quite good due to their simple design. Also, manufacturers tend to make multiple varieties of this lens for all levels of photographers, be it beginner, amateur, or professional. Lenses like Nikon’s 50mm f/1.8G and Canon’s EF 50mm f/1.8 II are great budget options with wide maximum apertures that can dramatically expand a beginner’s capabilities compared to a kit zoom lens. Or, if you are a professional, there are higher quality optics like Zeiss’s Otus Distagon T* 55mm f/1.4 Lens that are designed to provide near-perfect imagery, at a cost.
Beyond a normal lens, photographers can find themselves wanting or needing a little more reach, this is where telephoto lenses come in handy. Telephotos typically have focal lengths greater than 80mm and can extend to upwards of 400mm, though at that point they are usually referred to as super telephotos.
Short to medium telephotos are the first branches of this category and include the popular 85mm, 100mm, and 135mm options. Each of these lenses has a slightly different perspective, but the further you go, there will be more compression, shallower depth of field and, obviously, the distance you can be from your subject. Portraiture generally sees the use of these shorter lengths because photographers like to maintain a good working distance from their subjects since yelling across a field on a windy day isn’t ideal. Also, the shorter lengths are easier to shoot handheld and can be less intimidating, without losing the benefits of shallow depth of field and flatter features.
Standard telephotos and super telephotos are the next level of lens and offer the huge advantage of distance. If you need to capture a faraway subject, like a rare bird or a football player downfield, there is really no other choice. The drawback to these larger lenses is the size and aperture. The longer the focal length, the larger aperture required, which makes options like an 800mm f/2 lens practically impossible. But, aperture is an important consideration when purchasing a telephoto lens, especially if you are considering the use of teleconverters.
Additional size and weight, coupled with the narrow field of view, make image stabilization an essential feature of telephotos, especially once you exceed a focal length of 200mm. This technology will correct for camera shake, especially since the longer lengths amplify its appearance. Image stabilization is incredibly useful for shooting at slower shutter speeds and low ISOs, allows users to capture photographs that would’ve otherwise been impossible. Additionally, video shooters will greatly benefit from this tech as it will dramatically smooth out handheld footage.
Sometimes you just can’t fit everything into the frame, whether it is a group picture or your favorite piece of architecture. Wide-angle lenses, usually found at focal lengths of less than 40mm, fill in this gap with their large angles of view. They work well for landscape and architectural photography, as well as street photography, with the 35mm lens commonly found attached to a photojournalist’s camera.
Options like the 28mm and 35mm will slightly expand your field of view, which makes them critical to some users. Beyond just getting a tad more captured in the frame, wide angles offer a couple of notable benefits, due to their design. One of these is deep depth of field, caused by the shorter focal length. While not ideal for portraits, the ability to capture entire scenes in focus is ideal for landscapes and architectural photography. Also, photojournalists are afforded more room for error in focus on split-second shots.
The decision regarding focal length will be determined entirely by your needs, and just understand that the wider you get, the deeper the depth of field, the more distortion/perspective exaggeration, and usually the slower the aperture. There is one other category of wide-angle lens that is popular, and that is the fisheye lens. These lenses are found at the widest area of lenses with focal lengths around 8mm, like Rokinon’s 8mm f/3.5 HD Fisheye Lens. It offers a unique perspective by capturing a surreal 180-degree angle of view, which is great for conveying the overall feeling of a location as opposed to the limited field of view of most lenses.
The specificity of prime lenses allows them to be used to make high-performing lenses with a dedicated purpose. Macro lenses are such a type of specialty glass by enabling extremely close minimum focus distances, usually enabling a 1:1 magnification ratio for true-to-life sizes. They are also available in a variety of sizes, from wide to telephoto, though more commonly you will see telephoto options like the Makro-Planar T* 100mm f/2 Lens from Zeiss. These telephotos offer users a good working distance so that you won’t accidentally block light from hitting your subject or scaring away a tiny insect. If still life and product photography, or extreme close-ups of blooming flowers and other natural beauties are subjects of your photographic interest, then a macro prime lens is uniquely suited to help achieve the best image quality possible.
Another type of specialty optic is tilt-shift and perspective-correction. These options allow users to alter the tilt and shift of the lens axis compared to the sensor in order to correct converging lines or to adjust focus to a different axis. The advantages of these lenses are dramatic, and they are the only way to get movements similar to a large-format camera on a DSLR or mirrorless camera body. Image effects like keystoning, when shooting upwards at a building, can now be corrected in-camera to avoid the headache sometimes associated with dramatic edits made in Photoshop.