Prime and Zoom Lenses

Prime and zoom lenses each have their advantages, but the flexibility of zooms make them especially appealing to beginning photographers.

Once you make up your mind about what focal length you'd like, choosing between prime and zoom lenses will further narrow the number of lenses you have to consider.

Like so many other decisions you make about camera gear, you need to start with WHAT you want to photograph and HOW you plan to use your camera.

Clearly a large, bulky zoom lens is just fine if you take your camera out once a month for a day trip, but it's less appealing if you want to travel and take pictures without drawing a lot of attention to yourself.

In the paragraphs that follow, I'll talk about the big differences between prime and zoom lenses so that you can take the next step on your journey to the best digital SLR lens.

What's a Prime Lens?

A prime lens has a fixed focal length.

The focal length of the lens is set to one number and cannot be changed. If you want to change your angle of view when using a prime lens, you must physically move the camera back and forth.

If you want to use several different focal lengths, then you'll need a variety of prime lenses. To take photos at 28mm, 100mm and 300mm you'll need 3 lenses, one for each focal length.

So why would anyone want multiple prime lenses when a single zoom could cover the same range?

They're High Quality

Ask any professional photographer about the benefit of a prime lens and the answer will be the same: it takes clearer photos.

Since they don't have a lot of moving parts like zooms, the glass inside of a prime lens is very precise.

In the early days of zoom lenses, there was a big difference in quality. Today a high-end zoom can capture images that have the same quality as a prime.

But there is a difference in cost. If you want to get a zoom lens that performs as well as a prime, you're going to spend a lot of money.

They Don't Weigh a Lot

Advantage number two: prime lenses are pretty light.

An 80mm to 200mm zoom lens can add a lot of weight to a digital SLR camera that is already bulky to begin with.

If you want a digital SLR camera with maximum portability, just attach a really nice 50mm lens to it and go on your way.

Small prime lenses paired with small sized digital SLR cameras are the perfect tool for the digital SLR photographer on the go.

They Aren't Expensive

Here's the best part: you don't have to break the bank to get a superior lens for your digital SLR camera.

Since they have been around for so long, and since their construction is simpler (remember, less moving parts) you can get a great prime lens for a fraction of the cost of even a basic zoom.

You can also get reasonably priced prime lenses with wide apertures that let in a lot of light. These are the perfect lenses for photographers who want to photograph in low light without using the flash.

What's a Zoom Lens?

A zoom lens has a variable focal length.

These are the most common types of lenses available for digital SLR cameras today. In fact, the standard lens packaged with many new digital SLRs is an 18-55mm zoom.

It makes sense: the flexibility offered by these lenses is very appealing to photographers who are just starting out with an SLR.

Flexibility is the key selling point of all zoom lenses. Unlike primes, they tend to be expensive, heavy and don't always use the highest-quality glass.

They offset all of these disadvantages by allowing you to stand in one spot and get exactly the composition you want.

Zoom Focal Lengths and Zoom Power

Since a prime lens doesn't change its focal length, it can be described using one focal length number (i.e. 50mm).

But zooms cover a range of focal lengths, so any zoom you look at will always reference two numbers: the wide angle setting and the telephoto setting.

For example, a 28-135mm zoom can be described like this:

  • Wide angle setting: 28mm
  • Telephoto setting: 135mm

The greater the difference between these two numbers, the more powerful the zoom.

Zoom power indicates how much focal range a particlular lens can cover.

For example, a 28-300mm zoom is said to be more powerful than a 28-135mm zoom. The 28-300mm covers a wider range from wide angle to telephoto.

You can determine the power of any zoom by dividing the telephoto setting by the wide angle setting. Here are some examples:

Wide AngleTelephotoMathZoom Power
18 mm55 mm55 / 183.06 (3x)
10 mm14 mm14 / 101.4 (1.5x)
70 mm300 mm300 / 704.29 (4x)
28 mm300 mm300 / 2810.71 (11x)

Types of Zoom Lenses

In Step 1 of this digital SLR lens guide, I mentioned that there are 4 primary classes of lenses: wide angle, standard, telephoto and super-telephoto.

Turns out the zoom lenses also fall into similar groups:

Zoom ClassRange
Wide Angle to Wide Angle10mm to 28mm
Wide Angle to Telephoto28mm to 300mm
Telephoto to Telephoto100mm to 600mm
Super Zoom18mm to 300mm

While the last category (Super Zoom) might seem like the obvious choice here (put one lens on your camera and never take it off!) the super-zooms do not yet have the same optical quality as the specialty zooms.

While a super zoom is a good lens to get started with (since it gives you a wide range of photographic opportunities) once you discover what you love to photograph, then I recommend getting a specialty zoom that just covers the range you use the most.

Finding a Lens Example

In Step 1, I introduced you to Chris, who's looking for a good lens to photograph his son's little league games.

Chris owns a Nikon and has decided that he wants a Telephoto lens.

Because the action at a little league game can move around a lot, he opts for a telephoto zoom, because this will give him more freedom to zoom in and out from the sidelines and capture all the action.

His digital SLR lens wish list now looks like this:

  • Lens mount: Nikon
  • Lens focal length: Telephoto
  • Lens type: Telephoto to Telephoto Zoom

Up next: maximum aperture.

Continue to Step 3
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