Why You Should Go Beyond the Kit Lens

Many interchangeable-lens cameras, be it DSLR or mirrorless, are sold today with what we call "kit" lenses. Current kit lenses, in general, thanks to computer technology and advanced manufacturing techniques, are more capable and of higher quality than those of yesteryear. However, many of us who use interchangeable-lens cameras feel the gravitational pull of other lenses that are not yet in our bags.
Adding lenses to your quiver is all about choices and selection and, in photography, we often find ourselves at a sort of "gear crossroads." The first crossroad is during the initial purchase of a camera: what brand, how many megapixels, which kit, etc. The next is when we debate which lenses to add to our camera bags or, to not add lenses at all.

Focal Length Explained

Before we go any further, let us talk, very briefly, about lens focal length. For years, with SLR and DSLR cameras, the 50mm focal length has been known as "normal" or "standard." The perspective afforded by the 50mm lens, when used on a 35mm film camera or full-frame DSLR, closely approximates that seen by your own eyes, minus your peripheral vision. Got it? Good.
What is focal length? The focal length of a lens is the distance from that lens's rear nodal point to the image plane (often illustrated by the "Φ" symbol on the top plate of a camera body) is the distance from that lens’s rear nodal point to the image plane when the lens is focused at infinity. Changing this distance by zooming or putting different lenses on a camera changes the photographer's field of view.

The wrinkle... digital cameras with smaller sensors will change the perspective of that 50mm lens, since your eye (and the sensor) is looking through a smaller portion of the projected image circle. So, when shopping for lenses, always pay attention to the "35mm equivalent" specifications to apply what you just read about 50mm lenses and what you are about to learn about the other focal lengths. For the purposes of simplifying this article, we will keep the numbers in the full-frame or 35mm world.