Prime Lenses Explained
A prime lens is a lens whose focal length does not change. When a photographer using a prime lens wishes to change the framing of his subject, he must physically move. That may sound inconvenient, but prime lenses have many positive qualities that certain photographers find desirable.
It is a misconception that the word “zoom” describes a lens that gets very close to distant subjects. Lenses that magnify distant objects are called “telephoto”. A zoom lens is one that offers the capability to change focal lengths — by pressing a button or turning a ring the photographer “zooms”, changing the field of view and re-framing the subject without having to reposition the camera.
A prime lens is the opposite of a zoom. It has only one field of view and does not have the capability to change its focal length (zoom). Instead when the photographer wants to get a different framing on the subject, the camera must be repositioned.
What makes prime lenses desirable?
Lacking the capability to zoom sounds like a serious downside to prime lenses, so there must be a good reason why many photographers prefer them, right? Right.
Prime lens construction is much less complicated than zoom lenses, making them cheaper to manufacture and often significantly lighter than comparable zoom lenses.
The simpler construction of prime lenses means less interior elements to affect light passing through, making it possible to get very good image quality out of affordable lenses. Professional-grade lenses usually have excellent image quality regardless of whether they’re prime or zoom, but when you’re talking affordable consumer-grade lenses, very satisfying image quality is usually found at a reasonable price in prime lenses.
Prime lenses are capable of much wider maximum apertures than zoom lenses. This means the opening through which light passes can be opened up to a very large diameter, opening the door to low-light photography and selective focus (making single subjects pop with blurry, out-of-focus backgrounds). While the fastest zoom lens you’ll find goes to f/2.8, it’s not uncommon for prime lenses to be capable of f/1.8 or f/1.4 (the smaller the number, the larger the opening).
Here is a sample photograph that was made possible by a prime lens, specifically the Canon EF 24mm f/1.4L USM.
- Shot hand-held at 1/30 sec., any slower at we would start seeing blur from my shaking hands. The small size and light weight of this lens made holding it steady much easier.
- Shot at ISO 1600, this setting is near the limits of where my camera begins to generate serious noise.
- These settings were made possible by the lens’ ability to shoot at f/1.4, a very wide opening that let in lots of light. Getting as much light as possible in through a wide aperture makes it possible to use blur-eliminating shutter speeds and lower ISO settings for higher image quality.
Other Down Sides
Not being able to change focal length means that if you want a different field of view, you need to use a different lens. As a prime lens user, you will get used to changing lenses. You need to be careful not to drop your glass, and try your best to keep dust and other foreign elements from entering your camera and damaging the sensor.
Are prime lenses right for you?
Only you can answer this question. Lens selection is a key element of photography and often one of the defining factors of a photographer’s personal style. Some photographers need the versatility of changing their framing in an instant with zoom, and cannot afford to miss shots in the time it takes to change lenses. Others seek results that require the specific features of prime lenses.
If you are wary of having to change lenses often, consider that using prime lenses is an entirely different mindset. It involves making a conscious choice to make very specific types of photographs. It’s not about changing lenses fast and often to get every shot imaginable, but rather going out with the knowledge that you want to make specific types of images and have made a deliberate choice of lens to suit your vision.
If you have never used a prime lens and are curious what they’re all about, I suggest considering a “nifty fifty” — a 50mm f/1.8. These are small, light, and extremely affordable prime lenses available for almost all modern DSLRs. This is a gateway lens for many photographers, offering impressive results in a small package that costs very little. The Canon EF 50mm f/1.8 II is just $99. Nikon’s version is $115, but we don’t have a review of that lens yet. Nikon users should also check lens compatibility with their cameras, as some lenses lose auto-focus on certain cameras.