For those who are new to all this, a prime lens is merely a fixed focal length lens. It just means that unlike your 70-200 mm zoom lens that allows you to use focal lengths between 70mm and 200mm, a prime lens will only shoot at a fixed length. Some common prime lens lengths are 24mm, 35mm 50mm, 85mm, 100 mm, 200mm, etc.
Here’s a rundown of the main advantages prime lenses have over zooms...
1. Prime lenses tend to be “faster” than zooms. What I mean by that is that they have a larger aperture (lower f-stop number) and allow more light into the camera.
2. Prime lenses tend to be sharper because they tend to have fewer optical compromises. Zooms require more lens elements and moving parts which could impact sharpness.
3. Prime lenses are typically smaller and lighter than their zoom-lens equals.
4. Prime lenses force you to think more about composition since you can’t just zoom your way out of a problem.
5. Prime lenses (at least the great ones) may offer you more control over your photography. They have features like depth-of-field scales (used for hyper focal distance calculations) or aperture rings.
There are three primary disadvantages to all these features...
a. You have less flexibility.
b. You have to buy and carry more lenses to achieve coverage of the same focal lengths.
b. Good prime lenses can be expensive.
The basics of zoom lenses...
A zoom lens is a mechanical assembly of lens elements for which the focal length (and thus angle of view) can be varied, as opposed to a fixed focal length lens.
The main advantage of zoom lenses is flexibility. You can carry just one lens that covers a wide range of focal lengths.
As for which is better, primes or zooms, the answer is (as it always in with photography) IT DEPENDS. It depends on what you want to accomplish, your skill level, the type of photography you practice and your budget.
As for my own preferences, I generally prefer primes. When I have a choice, I shoot with primes, but there are indeed times when I want a zoom lens. They are affordable, flexible, convenient and versatile. The Olympus M.Zuiko Digital ED 40-150mm f/2.8 PRO Lens is one of my favorite zoom lenses for bird photography. There are times when it is just the best choice. Otherwise, I tend to use my Olympus M.Zuiko Digital ED 300mm f/4 IS PRO Lens and may use the Olympus M.Zuiko Digital MC-14 1.4x Teleconverter when I need more reach.
I almost photograph birds exclusively using these lenses with one exception. When I am at places in the Alligator Farm or Gatorland and I can get very close, I will use a lightweight zoom lens, the Olympus M.Zuiko Digital ED 12-100mm f/4 IS PRO Lens which is great for hand-held flight shots when the birds are close.
Everything in photography involves a trade off. Zooms typically have more flaws than prime lenses but primes are more expensive and you have to carry more of them. Even though I prefer primes, I am NOT saying you shouldn’t buy a zoom lens. As you can see, I do own two myself. And the good news is that today's zooms are better than ever before.
I do believe (especially for those shooting video or those who need super telephoto lenses) that a very fast prime lens is the best way to go, if budget allows. Your mileage may vary.
If you are unsure of which way to go, my advice is to rent before you buy and put each lens you're considering through its paces. Decide if it's right for you and then pull the trigger.
Scott Bourne Bio
Scott Bourne is an Olympus Visionary and a professional wildlife photographer, author and lecturer who specializes in birds. He was one of the founders of This Week In Photo, Founded Photofocus.com and is co-founder of the new Photo Podcast Network (photopodcasts.com.)
Scott is a regular contributor to several photography related blogs and podcasts and is the author of 11 photography books.
Scott is available to speak to your birding group, photography group and for both private and small group bird photography workshops. For more information on engaging Scott as a speaker or workshop leader, or for image licensing and print information, please e-mail email@example.com.