Join Ben Long for an in-depth discussion in this video Understanding lenses, part of Introduction to Photography.
- There are a lot of complex parts in a modern camera but one of the most critical components is the lens. It's the lens that focuses the light from your scene onto the image sensor in your camera. And different lenses will do a better or worse job of focusing that light. A superior lens will yield an image with sharper details, better contrast, richer colors. Also sometimes, a lens just has an indefinable quality that you might prefer, even if you can't identify exactly why. But image quality is not the only thing that separates one lens from another.
Every lens is engineered to have a specific focal length. This is the physical length of the lens. And a lenses' focal length has a profound impact on what you will see through the lens. This is because focal length determines the lenses' field of view. Field of view should not be a confusing concept to you because you live with a visual field of view all the time. Right now, your eyes are revealing a certain field of view to you. If you include the full periphery of your vision, you could say that your field of view is almost 180 degrees. But a lot of that, this stuff out here, is very indistinct.
We think of the effective field of view of the human eye as narrower, somewhere around in here. Any lens that offers an equivalent field of view to this, is considered a normal lens. On a 35mm film camera, or full frame digital camera, a 50mm lens will be normal. On a camera with a smaller sensor, and it will be a shorter lens that is normal. A lens with a focal length that is shorter than a normal lens is considered wide-angle. With these lenses, you'll see a much wider field of view than you will with a naked eye or with a normal lens.
Lenses with a longer focal length, longer than normal are considered telephoto. A telephoto lens has a very narrow field of view but it also has a lot of magnification power. With it, you can enlarge distant objects. Now, some of these lenses are better for some applications than others. For example, if you were shooting sports, or wildlife, subjects which are usually pretty distant, you'll want to use a telephoto lens. If you want to capture lots of details in a narrow space, then you'll want a wide-angle lens. As you'll see later, lens choice affects much more than field of view.
You can dramatically change the sense of space and geometry in a scene, depending on the lens that you choose. The lens that came with your camera is probably a zoom lens. This is a lens that has a variable focal length. As you zoom out, you are shortening the focal length and going to a wider angle. As you zoom in, you're lengthening the lens, narrowing its field of view, and magnifying your scene. Your cell phone camera most likely has a fixed-focus lens, what is sometimes called a prime lens. You can get either zoom or prime lenses for your SLR or mirrorless camera.
Prime lenses, sometimes offer slightly better image quality and usually allow more flexibility in low light. You don't need to worry too much about lens choice right now. The kit lens that came with your camera should offer a good range of everyday focal lengths. As you practice with it you'll get a better idea of what types of focal lengths you'll like to use, and when. With more experience, you'll learn if and how, you want to expand your lens collection.
Then it's time to take to the field and examine the rest of the factors that influence the quality of your photographs, including light metering, focus, composition, and flash. Ben also introduces techniques for shooting portraits and shows what you can do with an image editor in post. Last but not least, he'll provide a roadmap for learning more with the lynda.com extensive library of photography training. The path to becoming a better photographer begins with the first step. Start here!
- Exploring cameras and lenses
- Understanding media
- Controlling exposure
- Composing with autofocus
- Shooting portraits
- Understanding form and geometry
- Exporting and editing digital images