Noteworthy Lenses – Nikon Nikkor 20mm ƒ/3.5

It’s time for another examination of a noteworthy lens. Last time we looked at the Minolta Fish-Eye Rokkor-X 16mm F/2.8, and again we’re checking out a wide-angle lens from the Land of the Rising Sun. It’s Nikon’s Nikkor 20mm F/3.5 AI-S. Made in 1981, this thirty-odd-year-old lens remains one of the best wide-angle lenses for the F mount system, and is a serious contender for adapted mirror-less ultrawide of the year.

Lighter, more compact, and less expensive than modern Nikkor lenses of similar focal length, the 20mm F/3.5 AI-S is a lens for which it’s easy to justify ownership. And since the optical performance of this lens is equal to those expensive modern lenses, ownership should be a foregone conclusion. I’ve qualified the previous statement with the word “should” because not everyone will love this lens. For some shooters the requirement that it be focused manually will be an unfortunate deal-breaker, but for those who embrace the process and eschew ultrasonic, auto-focus motors, the Nikkor 20mm F/3.5 will be a real gem.

Nikon’s F mount Nikkors have a long and storied history. They comprise the oldest lens range still in production and they’ve been going strong for more than 50 years. Over this span there have naturally been some revisions. Beginning in the late 1970s the range was revamped to allow for automatic indexing at maximum aperture. These new lenses, dubbed AI, allowed the camera to know the aperture of the lens without the lens being stopped down. Further developments in the 1980s would allow for Nikon cameras that could automatically adjust the aperture of the lens for use in Program and Shutter-Priority modes. The lenses made for these cameras would be referred to as AI-S lenses.

There’s little to physically distinguish any given lens from a lens of a different era. Aside from a small change to aperture text colors (sometimes), aperture ring shape, and a notch on the back of the lens, they all look very similar. Knowing what to look for on the lens and keeping in mind what camera the lens will mount to are important factors when deciding what type of lens to buy.

Mirrorless users have it easy. Any Nikon lens will mount to an adapter and then onto your Sony a7 (for example) without any issue. Buy at will and go shoot.

For Nikon camera users, it’s a bit more complicated. Buying older “non-AI” or AI lenses can lead to compatibility issues with modern Nikon DSLRs. Some very old Nikkor lenses can even damage the auto-indexing tab on modern FX and DX cameras, such as the D610. To avoid breaking a full-frame masterpiece the wisest option is to simply shop for AI-S lenses, as these are compatible with every Nikon SLR made since 1959. To determine if a lens is AI-S, look for the minimum aperture number on the aperture dial to be painted in orange, and check for a vertical notch positioned just above the lens locking notch in the metal lens mount.

But enough of all that. Let’s get to the fun stuff.

The Nikkor 20mm F/3.5 AI-S has an angle of view which is 94º when shot on a 35mm film or full-frame Nikon FX camera. What this means, simply, is that the lens absorbs a lot of whatever it’s pointing toward. This ultra-wide view is excellent for congested city streets, architectural shots, interior shots where space is limited, or the vast and impressive vistas of landscape shooting. Very rarely does one worry that something will be out of frame or out of focus. This is about as close to point-and-shoot as an SLR lens gets.

Used on a crop-sensor camera such as Nikon’s DX range, the angle of view comes in around 74º, so there will naturally be less coverage. Even handicapped in this way, the lens still offers a respectably wide 30mm focal length. This difference is a product of crop-sensors, like those found in DX and mirror-less machines, and the math is simple once the concept is understood. While the shooter loses some focal length, a happy byproduct is the elimination of the mild vignetting typically encountered with wide-angle lenses- more on this later.

Whatever the size of the sensor, practical use of the lens is a real pleasure. This thing has phenomenal build quality. At 235g it’s weighty, but not heavy. Entirely metal construction in a compact form imbues the lens with a feeling of quality. The focus ring spins with clinical fluidity and is lightly weighted to allow focusing with only one finger. Rotational action is kept to a relatively short 70º so focus is extremely quick, and the inclusion of a focus-scale makes it difficult to miss a shot for lack of focus. The aperture ring clicks solidly in single-stop increments from F/3.5 to F/22. Filter threads are metal and use 52mm diameter filters, and the metal lens mount is typical of Nikon’s dedication to exceptional machines.

Optically the lens is outstanding, with a few caveats. Getting to the positives first, color-rendition is fantastic due to Nikon’s exceptional coatings. There’s no chromatic aberration (the purply-colored fringes found in high-contrast areas of an image), and sharpness is superb. The edges of the frame are slightly softer than the center when shot wide-open, but it’s really a negligible lack of detail only seen under harsh magnification. Stop the aperture down to F/5.6 or F/8 and sharpness becomes uniform throughout the frame, and remarkable for its quality. Flaring and ghosting are virtually nonexistent.

If this lens has a weakness it’s in its tendency for vignetting, or light fall-off. When shot wide open the effect is pretty heavy, resulting in darkened corners creeping in from the outside of the frame. In certain situations it can lead to an interesting artistic affect, but in all honesty it’s usually undesirable. The lens in question isn’t the worst culprit I’ve shot, but there are certainly situations where the vignetting is just too heavy. Luckily if one stops the lens down a bit the fall-off becomes substantially mitigated. At F/5.6 it’s barely visible, and at F/8 and smaller it’s all but disappeared. Also important to remember is the ability of modern software, such as Lightroom, Aperture, and Photoshop, to easily correct unwanted vignetting.

As with any wide-angle lens, distortion can be a problem in certain shooting situations. The optics are very well-corrected, but when shot too close to a subject there’s a tendency for stretched features and oblong noses. This isn’t a knock on this particular lens, simply a product of the mathematics of wide-angle optics. Under normal shooting conditions the lens shows mild distortion of the wave variety in areas where parallel lines run close to the edges of the frame. It’s not extreme and can be left alone in most cases. In instances where distortion is strictly prohibited it can be sussed out in post-processing. Methods of doing this can be found elsewhere; this is Casual Photophile, not Obsessive Photophile. Rest-assured that for most shooters the lens will be corrected well enough, even without post-processing.

The 20mm focal length is one of the lesser-celebrated lengths, but this in no way diminishes the impact of its photos. The images produced at this focal length can be counted among the most dramatic of all. Shoot a standard 35mm or 50mm lens for a few months and switch to the 20mm. The difference is drastic enough to call it an entirely different type of shooting. Shooting an ultra-wide, one starts to see the world differently. There’s a certain dynamism to the commonplace. It pulls subjects closer and pushes backgrounds way off into the distance. It can make motion look faster, distances look vaster, and cramped spaces less claustrophobic. It’s an undervalued focal length, and one all photographers should experience.

Of Nikon’s range, the 20mm F/3.5 AI-S is one of the best deals around. Ultimate quality at an affordable price, it’s a lens that will bring a new dynamic to a number of photographic styles. Nikon or adaptable mirrorless users shouldn’t be without this lens. Artistically it’s a lens that can create astounding images. Technically it’s one of Nikon’s best. Any way you look at it, it’s a noteworthy lens.

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