After more than 30 years, Nikon has changed the optical design of its 50mm f/1.8 lens. But how does the new model compare to its predecessors? Richard Sibley investigates
Perhaps the first noticeable difference in the new 50mm f/1.8 lens is that it is a G-series model, meaning that it doesn’t have an aperture ring. Although there are still a handful of older D-series optics in Nikon’s line-up, the vast majority of the company’s AF lenses are part of the G series, which as standard don’t have aperture rings.
Although this will be frowned upon by some, G-series lenses can be used with all Nikon AF cameras, whether film or digital, going back as far as 1986. However, they are not compatible with manual-focus cameras.
One major advantage of the new lens comes via the introduction of an internal AF motor. The two previous AF versions of the 50mm f/1.8 optic rely on a motor in the camera to drive an AF screw in the lens.
This means that neither the original nor D versions of the 50mm f/1.8 lenses work on the entry-level Nikon DSLRs, such as the D40, D40X, D60, D3000, D3100, D5000 and D5100. The fact that the new AF motor is a Silent Wave Motor (SWM) is an added bonus, meaning the new lens should be fast and quiet when focusing – great news for those wishing to shoot video.
Of course, it is the optical changes that will most interest photographers. The introduction of a new aspherical element takes the construction of the 50mm f/1.8G to seven elements in six groups, and is designed to reduce comatic and chromatic aberrations. These optical distortions have previously been most prevalent when shooting with a large, fully open aperture, and are the Achilles’ heel of many a 50mm f/1.8 lens.
Designed primarily for digital camera sensors, the new lens has been coated using Nikon’s Super Integrated Coatings, which should help to improve colour accuracy and contrast, and reduce ghosting. The aperture blades themselves have also been improved and are now curved to create almost circular bokeh, compared to the heptagonal shape created by the older lens aperture designs.
So, while the emphasis may be placed on the inclusion of an aspherical element, there are a number of other small changes that should significantly improve the performance of the new 50mm f/1.8G lens.