Measuring lens quality
Looking to upgrade your lenses? Here are some things you may want to look out for…
What would you rather have, a better camera or a better lens? The truth is, both will give you an upgrade in picture quality and performance, but a goodquality lens is likely to last you for many more years than a camera body. That’s why it’s worth investing more in quality lenses where you can.
Of course, it may well have been the lure of L glass that brought you to the Canon system in the first place. The Luxury (for that’s what the L stands for) line of zoom and prime ‘red rings’ combine professional build quality, weather-sealing and premium features such as the latest Image Stabilizers and fulltime manual focusing with sparkling glass. They also tend to be ‘fast’ lenses with large maximum apertures, corrected to produce sharp images even when they’re used wide open.
Lens quality can be measured in a number of ways. High on the list of desirable qualities, of course, is sharpness, but contrast, colour and bokeh are equally important aspects to consider when weighing up whether a lens is right for you – or within your budget, at least. Take Canon’s full-frame EF 50mm lens range. Currently there are three to choose from: an entry-level 50mm f/1.8 STM, a 50mm f/1.4 USM mid-ranger and a top-of-the-line 50mm f/1.2l USM. All three offer fast maximum apertures, making them good options for low-light photography and for creating portraits with a limited depth of field. In the right hands, all are capable of making sharp images. But the price difference? You could pick up a dozen copies of the f/1.8 for the same price as a single f/1.2 lens.
How a lens has been designed to counteract imperfections or ‘aberrations’ is also a sign of quality. Despite the advances made in lens technology, chromatic aberration or colour fringing remains a problem. This optical phenomenon is similar to the effect you see when light passes through a prism, with the different wavelengths of light becoming separated. It leaves a coloured halo around high-contrast objects that can make images appear less sharp. High-quality lenses usually include a number of low-dispersion elements that reduce the degree to which the different wavelengths are dispersed as they pass through the lens. Cheaper lenses don’t have these corrective elements, and pictures taken with them will require more digital corrections when you process them.