Image sharpness is an important part of the equation when purchasing a new lens. Who among us has purchased a lens without first inquiring about, among other things, how sharp the lens is? Anybody?
Don't get me wrong. Lens sharpness is an important piece of criteria when it comes to purchasing a new lens and that's because, just like you, I only want sharp lenses regardless of whether the lens is a pricier OEM lens or a lower-priced, third-party lens. If the lens isn't sharp, "Feh—I don't want it."
Photographs ã Allan Weitz 2020
Now here's the ironic (and in my opinion, the funny) part of the story—some of the most iconically famous photographs ever taken aren't sharp. Many good examples of sharp and not-so-sharp iconic photographs were taken during WWII. Joe Rosenthal's photograph of American soldiers raising the flag on Iwo Jima is a sharp photograph. Many of Robert Capa's strongest D-Day invasion photographs tended to be blurred, and many of these are Capa's most powerful and best-recognized images.
The bottom line is "sharp" isn't the end-all of the medium. If anything, it's often the blurry elements that catch our eye and make us want to linger a while longer.
Taking sharp photographs is not a challenge once you understand how your camera and lens work together. You can then begin pushing the limits of what your lenses can and cannot do, and that's where creative types with a bit of curiosity can find the sweet zone—the space that makes your lens sing.
The two photographs, above and below, of a backlit Canna Lily leaf, were taken with a pair of Nikon lenses. The top photograph, which is rich in edge-to-edge detail, was taken with a Nikon Micro-NIKKOR 55mm f/2.8 AI-S at its closest focusing distance (1:2x) at f/11. The lower photograph was taken with a Nikon NIKKOR 50mm f/1.2 AI-S. Because the Nikon 50mm f/1.2 only focuses down to about 18" (0.18x), I used a Vello 16mm Deluxe AF extension tube to replicate the focus distance of the 55mm macro lens.
Though the photographs are compositionally similar, they are dramatically different in terms of mood and visual fluidity. The top photograph is clinically sharp and faithfully renders the structure of the leaf. This is what you expect from a flat-field macro lens.
The bottom photograph also renders the structure of the leaf but "leaves" more to the imagination. Rather than the tight fibrous veins running in curved, tightly knit rows in the sharper macro photograph, the photograph taken with the 50mm f/1.2 and a 12mm extension tube renders the leaf in a soft, swirling manner. The leaf is still recognizable for what it is, but rather than a clinical representation of the leaf, the leaf is now rendered, or interpreted rather than reproduced.
As for which of the two photographs is the better photograph? They're both good photographs. The answer is purely subjective.
Striking a Balance Between Technical and Technique
I've used and owned many extremely sharp lenses over the years, and as the megapixel count of my digital cameras seemingly doubles every two to three years, I've been particularly mindful of how my favorite lenses hold up every time I upgrade my cameras. Most of my favorites have fared well over time. Most of those that no longer measure up to the demands of 40-plus megapixels, I either trade in or donate to worthy causes.
There are some lenses, however, that I will never do away with, not because they hold their own when pitted against high-resolution camera sensors, but because they render incoming light in a manner other lenses do not. They're not necessarily the sharpest lenses in my bag, but the pictures they take are gorgeous in a way that's unlike the other lenses.
The trick is to learn the characteristics of your lenses, and when possible, push the lens into use in a way it was never intended to be used. The results can often be wonderful. The pictures may not be sharp in the classic sense, but this doesn't mean they aren't good—or fantastic photographs in spite of the fact they are optically flawed.
Voigtländer's Nokton 75mm f/1.5 portrait lens is an extremely sharp M-mount lens that can be easily adapted to other camera systems. It is an example of a lens that can render an image tack-sharp corner to corner or, when desired, render the same subject in a dreamy haze. When photographing subjects from midrange at wide apertures, the lens does a splendid job of separating the main subject from the foreground and background. What's sharp is incredibly sharp and what's not in focus melds away pleasingly. What I find particularly interesting is when the lens is used at its closest focusing distance. Add 10 to 20mm of extension tubes between the camera and lens and you can now start taking photographs that display a unique visual signature that draws the eye straight into the frame. This holds true for many lenses when pushed beyond their optical comfort zones. But as they say, "Nothing ventured, nothing gained…and no new ways to take cool photographs."
For example, the angled shadow play photograph of a window, aluminum siding, and security camera (above left) show off the Voigtländer's resolving power. The photograph of raindrops on an aluminum café chair (above right) was taken at the lens's closest focusing distance (27") at f/2. The center displays a sharp band of fluted aluminum and raindrops that fade off softly fore and aft. Regardless of personal preferences as to which photograph is the better photograph, both are of equal image quality.
Over time, I've managed to photograph many chairs I've encountered along the way. I'm especially attracted to pairs of chairs without human occupants. Depending on the scenario, I will sometimes stop down for maximum sharpness, while other times I try to separate the chairs from the foreground and background, not unlike a conventional portrait.
In the photograph of an empty storefront (above left), a small aperture brings the foreground and background into focus with the table and chairs. On the right, I stopped down the lens just enough to maintain focus on the chairs while the foreground and background go soft. It would have been easy to maintain focus throughout the entire scene, but it's the soft rendering of the background that makes the chairs stand out and gives the scene a welcoming feeling. Stopping the lens down would eliminate the atmospheric signature of the image, which is a large part of the photographs visual appeal.
Pushing the Limits of Close Focusing
The closest focusing distance of a lens is determined by its design. Getting around this limitation is as easy as adding an extension tube, a bellows, or a close-up lens. I use all three of these accessories (most notably extension tubes) for getting in closer than my lens limitations because, depending on the subject and the lighting, this is where the magic happens.
The closer you get to your subject, the narrower the depth of focus, and this is when it starts getting interesting. The dogwood photo on the left was taken at the closest focusing point for a Zeiss 60mm f/2.8 Makro-planar. The image is sharp where it counts and notably ethereal in the background. The photo on the right was taken with a Voigtländer Nokton 75mm f/1.5 at its closest focusing distance with a 10mm extension tube added for closer focusing. The wider aperture of the lens captures a sharp central portion of the flower, variably sharp edges of the petals, and a highly atmospheric background. The stem of the flower, which is barely visible, trails away toward the left.
As you can see in this image, adding 20mm of extension tubes to the Voigtländer Nokton 75mm f/1.5 at closest focusing distance creates a plethora of optical aberrations that take the level of dreaminess even further. The sharp portion of the frame is a narrow band that runs diagonally across the frame, highlighting the surface of the leaf and the raindrops falling upon it.
Unique Visual Signatures: Some Lenses Have One and Some Lenses Do Not
Some lenses have what I call "signatures." The pictures they take have a look that identifies the lens that captured the image to informed viewers. It could be the nature of the bokeh at wide aperture, the level of micro-contrast in the details, or the way the image falls off as details fall into shadow. Over the years, I've owned at least two lenses I purchased specifically because they have unique optical signatures. One of these lenses—the Nikon 50mm f/1.2 AI-S, which was mentioned earlier in this article, is a fairly common lens that has been around for decades and is still in production. Aside from capturing photographs that have a haunting glow at f/1.2, stopped down to f/2, the lens gathers an incredible measure of resolving power while maintaining a glowing effect around everything not in focus.
As this image demonstrates, Nikon's NIKKOR 50mm f/1.2 AI-S not only captures incredible levels of swirling bokeh at wide apertures, but is also considered the sharpest 50mm normal lens at f/2. It holds its own when stopped down further, too.
What's also unique about this lens is that, according to many test facilities, the Nikon NIKKOR 50mm f/1.2 AI-S is sharper at f/2 than any other 50mm lens on the market and it maintains that high level of resolving power throughout its aperture range. Add the dreamy softness of photographs captured at f/1.2 with controllable levels of sharp depth of field in a simple, affordable manual focus lens.
Another unique lens is the Zeiss Hologon T* 16mm f/8, which is a tiny pancake lens produced by Zeiss Germany for use with Contax 35mm G-series film cameras in the mid-1990s. Easily adaptable to a Leica M-mount, I've used my 16mm Hologon on Leicas and Sony A7-series cameras with equally amazing results. (When used on a Sony A7-series camera, you MUST use the camera in silent Shutter mode to avoid damaging the camera's shutter mechanism.)
In addition to its tiny form factor and extreme wide field of view, the Hologon is virtually distortion-free when leveled on a tripod. Something it isn't, is fast—the Hologon has a fixed f/8 waterhouse aperture, which is essentially a perfect circle that creates bokeh unlike the bokeh you get from lenses containing conventional bladed apertures. The focus, which can be as close as a foot from the lens, is shallow in use, but what's in focus is incredibly sharp with stunning contrast, while what's not in focus blurs the way our eyes interpret what's out of focus to our own eyes.
Another quirk of the Hologon is that the edges of the frame are about two stops darker than the center of the frame. To compensate for this vignetting, each Hologon comes with a 2x center-weighted neutral density filter that clips onto the front of the lens. It does a good job of evening the exposure across the viewing field but reduces the effective maximum (and only) aperture to f/16. Truth is, most photographers skip the ND filter and make the darker edges, which can be quite dramatic, work for them.
These images demonstrate the Hologon's interesting attributes, including acute levels of sharpness, near-zero distortion, an extreme wide-angle field of view, and wonderful levels of bokeh.
Have you owned or used lenses that have unique signatures? If so, tell us about them and why you like using them, in the Comments field, below. We'd love to hear about them.
