How overblown is the issue of lens sharpness? It’s a loaded question, I know. If you were to give any credence to the chatter found on numerous photography forums, blogs, and test sites found around the Web, one might be inclined to think that lens sharpness is the only thing that matters. Unfortunately, a lot a people do indeed buy into the hype. I say “unfortunate” because the current cult of lens sharpness and the zeitgeist that they have fostered has, perhaps, done more harm than good for consumers who are simply looking to get the most value for their money when purchasing a new lens.
To help keep lens-related anxiety to a minimum, here are a few thoughts that you may want to keep in mind when preparing to buy a new lens or when assessing the quality of lenses you already own.
Lenses are Tools, That is All
Like a camera itself, a lens is just a tool that you use as an extension of your creativity. A “good” lens doesn’t automatically produce good work; a “bad” lens doesn’t automatically produce bad work.
Photo by huzu1959
Good and Bad are Relative
A good lens doesn’t mean it’s the best lens ever produced or even that it’s the best lens within a particular system. But, often, good is more than good enough. Kit lenses, for example, typically get a bad rap; this, however, is often undeserved as their bad reputation is usually more a function of perception than reality. Of course, no one in their right mind would seriously suggest their variable aperture kit lens can compete in every way with a “pro” level constant aperture zoom. But if the bottom line is the creation of an interesting photo, what does it matter? If the people looking at your image can’t tell (or don’t care) whether it was made with a supposedly bad kit lens or a lens with a decidedly stellar reputation, then you don’t have much to worry about.
Photo by Emilio Küffer
Lens Sharpness is Subjective
Who knows what sharpness even means? Everyone and no one. When some people talk about sharpness they are referring to overall resolution; others are referring to contrast or “micro contrast.” There are those who are mostly concerned with how a lens resolves fine detail, while others may place more value on center sharpness or edge sharpness. It seems everybody’s got their own interpretation of what sharpness is and, by extension, they’ve all got a preference for one kind of sharpness or another. If a lens meets your standards for sharpness, that’s all the justification you really need for it.
Photo by Tim Geers
There are Traits Other Than Sharpness
When considering the overall value of a lens, there are properties other than sharpness to take into account. Vignetting, flare resistance, focus speed, build quality — these are some things that any prospective lens buyer should think about.
Forget About MTF Charts
MTF (modulation transfer function) charts were devised as a graphical, objective representation of the optical performance potential of a lens. These charts have their place I suppose, but photographers tend to prefer real world testing. It’s one thing to read a chart and attempt to draw a conclusion based on plot points on a graph; it’s quite another thing to take a lens out and actually use it…in real life, so to speak. Perhaps you do lose the purported objectivity of the chart, but hands-on use is far more meaningful.
Photo by Will Cobb
Remember That Image Editing Software Exists for a Reason
One of those reasons is to help compensate for a lens’ imperfections. Whether you need to sharpen an image, correct distortion, or brighten up the corners, this can be done quickly and easily in post-processing. Granted, it is preferable for a lens’ tolerances to be such that you don’t need to do much work in post; but the fact is there is no such thing as a perfect lens. Software can help mitigate optical imperfections.
American novelist Tom Robbins once philosophized that humans, to our detriment, “waste time looking for the perfect lover, instead of creating the perfect love.” Photographers, don’t waste your time looking for the perfect lens. It doesn’t exist. But there are lenses out there that are perfect for your specific needs; in fact, I’d be willing to bet that you already own such a lens. All that’s left for you to do is learn to put it to perfect use.
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