Join Ben Long for an in-depth discussion in this video Why does the lens matter?, part of Foundations of Photography: Lenses.
Camera vendors are quick to extol the huge pixel counts in their cameras. Sometimes it's even written on the front of the camera itself-- that's that megapixel number. And certainly pixel count is important, especially if you like printing big images, but sometimes it's also a bit of a marketing ploy. It's a single number that a vendor can use to represent overall quality. This camera has 14 megapixels therefore it must be better than this one that only has 10, that sort of thing. There are a lot of factors that contribute to the overall image quality that your camera produces.
A very significant one is image processing that happens inside the camera itself and a camera that does a better job of interpreting the data that it collects will yield images with less noise, better color, and possibly better sharpness no matter how many pixels it may have on its sensor. But regardless of your camera's pixel count and no matter how great its image processing is, if you stick a lousy lens on that camera, you will get compromised images. I often hear people say, "Oh I am going to get that new cell phone with a five megapixel camera, because then I won't have to carry around my real camera anymore." There are some cell phones today that can take very good images but with current technology, there is no way that a tiny cell phone lens can compare to the lens on even a point-and-shoot digital camera, even if the point-and-shoot has a lower pixel count.
Unless you're specifically going for a grungy toy camera look, a quality lens is a must if you want images of high technical quality. I say technical quality, because you can take a compelling image with any camera and lens, but if you want to improve your chances of getting good sharpness, good contrast and good color then you want a good lens. Different lenses also impact your creative choices, possibly giving you more artistic control. For example, the focal length of your lens has a large bearing on the types of subjects that you can shoot and how you might shoot them.
This image, for example, lends itself to wide-angle shooting, which means you want a lens with a short focal length. The ability to shoot with deeper or shallower depth of field also gives you tremendous creative flexibility. So for example, you might find that for the types of shots you like to take, a ery fast prime lens with an extremely wide aperture is a better choice for you than one with a slower lens, because you'll be able to shoot with shallower depth of field. Finally, sometimes a lens just has an ineffable, un-definable quality about it. A particular way that it handles contrast. Maybe there's just something about it that you really like and so you learn to exploit that.
You don't have to have a great lens to shoot great images, but it sure helps. What you do need is the understanding of how to take advantage of your lens and that understanding begins with focal length.
- Understanding field of view and camera position
- Depth of field and lens choice
- How to choose a lens
- Examining lens features
- Using specialized lenses such as fisheye and tilt/shift lenses
- Focusing techniques
- Using filters
- Camera maintenance