Jargon buster

ring-type ultrasonic

This type of autofocus system is based on two electromagnetic rings. It’s usually rather speedy and quiet, and enables manual override by twisting the focus ring.

aperture rating

Smaller f-numbers equate to larger apertures, which pass more light through to the camera body. An aperture of f/1.4 is two-thirds of an f/stop faster than f/1.8. Size and weight Some newer designs of standard primes have a relatively complex optical path with a larger number of elements, making them bigger and heavier than usual. weather-seals Many Nikon lenses have a weather-seal ring on their mounting plates but, in this group, only the Tamron and Zeiss lenses feature comprehensive weather-seals.