In the by-gone days of film, it was widely and truly held that once you had a couple of reliable camera bodies and a flash, it was time to sink money into lenses, which we in the biz simply call “glass.” The reason was that aside from nice features and correct exposure, camera bodies didn’t actually contribute anything to image quality. No matter what camera you used, it was basically a light-tight box that held the film in the right place for you. The film, the lens, and most importantly the light, did the rest.
When digital came along, the waters got a lot muddier. For a long time, it was critical to buy expensive (sometimes absurdly expensive) cameras to get the best image quality. Thankfully those days are waning, and surprisingly good digital image quality can be in the hands of consumers where it once only graced the bags of top shooters.
This inversion in the cost structure of digital photography has an ironic consequence: extremely sophisticated, high-quality digital sensors behind extremely cheap lenses. In order to keep down initial purchase price, affordable digital cameras are usually offered for sale with a “kit” lens. While these lenses are cheap, lightweight, and versatile, they are most certainly the weak link in today’s photography. An eight or ten or twelve megapixel sensor combined with a modern image rendering system far outstrips the ability of the tiny, plasticky 18-55mm-class of lenses. I see this in my classes: cameras capable of amazing images burdened with lenses capable of ruining those images.
It’s not that these kit lenses are crap all the time. In bright sun or in unchallenging lighting scenarios, they do just fine. But most of the photographs made in the world are under less that perfect circumstances, and it’s there that cheap lenses disappoint. There are better lenses, but at a cost that might seem extravagant to amateur photographers. Nikon’s big AF-S zooms with ED glass elements, Canon’s L-Series lenses, and so on, are capable of holding up under the stress of extreme lighting compromises. Frequently the best photos in the world are made under such circumstances, and cheaper lenses just aren’t going to cut it.
Do yourself a favor. Consider giving your sensor the image it deserves, and buy a top-quality lens.