Prime and Zoom Lenses

One Focal Length or Many?

The second step on your path toward finding an SLR lens is to decide between prime and zoom lenses.

Each one has distinct advantages over the other, and your choice in the end will be a matter of weighing the value of the lens against its cost.

Since you've already made up your mind about what focal length you'd like, choosing between prime and zoom is further narrowing the field of digital SLR lens options.

Digital SLR Lens Guide

Introduction 1 - Focal Length 2 - Prime vs. Zoom 3 - Maximum Aperture 4 - First vs. Third Party 5 - Extra Features 6 - Pick A 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.

If you enjoy taking 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 couple of zooms 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, no 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 Designation

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 number, 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.

Zoom Specialties

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 Class	Range	Example
Wide Angle to Wide Angle	10mm to 28mm	Pentax 12-24mm
Wide Angle to Telephoto	28mm to 300mm	Canon 28-135mm
Telephoto to Telephoto	100mm to 600mm	Nikon 70-200mm
Super Zoom	18mm to 300mm	Tamron 28-300

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.

Lens Hunt 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: