20mm is not a focal length I have used frequently but it’s fun to work with — 35mm is pretty normal, 24mm is definitely wide but can still be used easily in many situations, its a nice focal length for travel and landscape, 20mm gives an extreme point of view. Because I won’t be using it regularly, I resisted buying the obvious and reportedly excellent Nikon 20mm f1.8G AF-S lens, instead choosing to save some money and look around for some older and cheaper options that would still deliver interesting images. I am not a review writer, but thought I would share my opinions and some sample images rather than facts and figures, I have deliberately kept any post processing efforts in Adobe Lightroom very minimal to give an accurate idea of how this lens performs.
Nikon have produced several 20mm lenses over the decades, AI and AI-S models are available in maximum apertures from f/2.8 to f/4 but I wasn’t too fussy on which and managed to get a reasonably priced, good condition Nikon 20mm f/3.5 AI-S lens from a good seller on eBay for around £200. It’s quite light for an all metal lens at 235 grams, only 5cm long including the mount and having been built in the pre-AF days, handles well with a very nice smooth focus ring and a proper aperture ring, on my D750 you can shoot in aperture priority and manual modes.
My lens was made in Japan in the late 1980s. On a lens of this age, there will be a variation in performance from lens to lens, based on how hard a life it has had, inevitable dust ingress between the elements and degradation of coatings. Mine is in excellent condition however it seems to be sharpest at close to medium distance rather than at infinity, likely a result of the design rather than my lens specifically. More modern lenses correct for close focus so are more versatile and meet today’s demands for higher resolution. Corners are not great, there is obvious lack of detail and distortion at all apertures, across the rest of the frame while I can get good sharpness, resolution is generally low by the standards of modern lenses, easily out-resolved by the sensor on my D750, but the lens does produce nice images with reasonable contrast, controls flare well even shooting into the sun and reproduces colour accurately. I don’t do landscapes so this is fine for me and I don’t feel an urgent need for the newer lens for the type of photography I am interested in.
Of course, this is a manual focus lens, however it is not at all challenging to use despite focussing screens on modern DSLRs that are far from optimum for manual focus, even wide open at f3.5, unless you are focussing on close subjects, there is reasonable depth of field.
For people photography around town it’s great, the focal length challenges me to get in close and small focus adjustments are all that’s needed given the large depth of field at middling apertures of f5.6 to f11 that I would normally use. That is where this lens will excel for me — I need good central sharpness, good colour and tonal graduations and comfortable handling, I get all of these and good value too from a thirty five year old lens. Definitely worth considering as an alternative to the new 20mm AF-S version.