Off-the-bat disclaimer: This is not an article about technicals. Mainly because I'm not exactly qualified to talk about gear specs (I leave that stuff to far more capable sites like DP Review). But more importantly, I feel the science behind a lens doesn't mean much unless you know what you want to shoot with it. So this article is about learning to think in terms of sensory input, and choosing the appropriate lens as it relates to what you want to say with your images.
So how can you do that? First, by knowing what types of lenses there are and understanding the basics of how they function. Yes, this part does dip a little into technical waters, but I'll keep the geek-speak to a minimum... :)
Wide Angle Lenses
These lenses don't only give you a more expansive view of a scene, they also create a sense of space. Elements may appear further apart, or further away than they really are. For example, photographing a car on a road with mountains in the distance will have a much different perspective when shot with a wide angle than with a telephoto lens. Wide angles also have a greater depth of field to capture more detail, even at large apertures.
Also called long lenses, telephoto lenses compress elements within a scene, making them appear closer together, or larger than they really are. At large apertures, they have a shallower depth of field than wide angles, making it easier to isolate subjects and create soft backgrounds.
As you may have guessed by these brief descriptions, wide angle lenses are often favored for shooting landscapes or sprawling scenes, while long lenses are used more often for portrait work or lifestyle images that call for intimacy. That's not to say you can't shoot portraits with a wide angle, or landscapes with a telephoto. It just depends on your vision for the scene and what you want to communicate to the viewer.
The two images shown above were shot just a few seconds apart, from the same position (about 5ft away), with the same aperture. As you can see, each one tells a little bit different story. The first frame gives us a broad look at what's going on (nothing special, just my daughter glued to her iPad on the couch in my office). The second image suggests a softer, almost secluded scene just by switching lenses. Neither is wrong, but depending on what my intentions for the image may be, one might work and the other probably would not.
Prime Lenses Vs Zooms
Both zooms and primes can be either wide angle or telephoto lenses. The one major difference is that prime lenses have only one focal length, where a zoom has a range. In addition, primes usually offer greater creative control over focus and depth of field because they have larger apertures (i.e. they are "faster").
At this point I'd be remiss if I didn't specifically mention the 50mm. It's considered neither a wide angle nor a telephoto. In fact it's the delineator that separates the two, because it's the one lens which most closely resembles how the human eye sees. Ironically, most photographers either dislike it or favor it, and both for the exact reason I just stated.
Practice With Your Mind, Not Just Your Eyes
Now that we have some basic lens properties out of the way, let's get back to the matter of selecting the right lens for the job. This part is much more subjective, but decidedly more important. It begins with asking yourself a few questions every time your shutter finger gets itchy...
- What's happening in the moment and what is the story I want to tell?
- Is there movement, a prominent gesture or an emotion I want to convey?
- Is there something I should include (or exclude) to make the story stronger?
- Do I want to capture a sense of grandeur, or isolate a notable subject instead?
Being able to answer questions like these will help you define your vision for a scene. The trouble is, it can be really tough to make a practice of. I'll admit, I forget sometimes. Especially when I'm in a hurry or feel pressured to capture something without thinking about what made me stop to photograph it in the first place.
It also helps to develop a familiarity with how your lenses "see". Knowing ahead of time (or at least having a sense of) what a scene will like look through a particular lens takes time. I'm still working on this, and suspect I always will. But this skill can have a tremendous impact on your choices and how strong your images are.
Right about now you might be thinking "What if I don't have time to switch lenses? What if I only have one?"
To that my answer is simple (and probably overused)... your best camera/lens is the one you have with you. Better to capture something than nothing. You can always scrap the photo if it turns out awkward, but you may never be able to go back and recreate the moment!