By MICHAEL PERKINS
AS SOME PHOTOGRAPHERS AGE, THERE IS A STRONG TEMPTATION to do more and more with less and less. For many, this manifests itself as a kind of divestiture, a relinquishing of toys. Maybe it’s just muscle fatigue, but, at some point in a shooter’s life, he or she makes a conscious decision to carry fewer hunks of gear into battle. Your approach to the work gets more complex, and, paradoxically, the mechanical doing of it gets more streamlined.
This is where the idea of a “go to” lens comes from, with photogs deciding that, yes, they can do nearly everything with the same hunk of glass. It becomes a bragging point: I shoot everything with a 24mm prime. I always use a 35. I don’t carry a big bag of stuff around anymore. But here’s the great thing: even a single lens is actually several lenses at once, since its optical properties change dramatically depending on aperture. That’s why, if you’re trying to take more kinds of pictures with fewer lenses, it’s important to do some homework on all the different ways they see.
One of the things it’s best to know about your lens is where its “sweet spot”, or optimum sharpness occurs across the aperture range. Turn on your trusty Google machine and you will find more opinions on how to determine this than there are recipes for apple pie, and that’s the tricky part. Optics are a science, to be sure, but they are also somewhat subjective. Translation: if it looks good to you, it’s good. So publishing a table that proves your argument on what “sharp” is to your satisfaction just picks a scab for someone else. You have to get away from the charts and do the field work. Shoot. Look. Compare.
The chart people believe, for example, that the sweet spot for a lens is always two f-stops less light than your maximum wide-open aperture, meaning that, say an f/1.8 prime would hit its sweet spot somewhere around f/3.5. However, on my own 35mm f/1.8, I get the most uniform sharpness, from center to corners, another stop beyond that, so my “go to” aperture on my “go to” lens is more like f/5.6. I know this is true, because I have set up a tripod and shot the same subject from the same distance through the entire range of apertures and visually compared them. You know, the real-world, old-fashioned way….observation.
The better you know every property of your lens, the closer you will get to one that does most of what you want, most of the time. More pictures with fewer toys, with time and labor saved as well.