The first 21mm lens released was the W Rokkor-PI 21mm f/4.5 (1962), which featured a symmetrical design similar to the contemporary Zeiss Biogon.

The third and final 21mm lens was the MC W Rokkor-NL 21mm f/2.8 (1971), which featured a retrofocus design that did not require the reflex mirror to be locked up, allowing use of the built-in viewfinder.

[1] When the Rokkor-PI f/4.5 was introduced, it was advertised as "a product of much painstaking work and research by the company's technical staff", which Erhard Bertele called "a mockery" in retrospect, declaring it "[an imitation of the Biogon] with seemingly insignificant small changes to the original Bertele design".

[4] In 1964, the suggested retail price of the Rokkor-PI f/4.5, with accessory viewfinder and leather case, was US$209.50 (equivalent to $2,060 in 2023).

[6] The Rokkor-NL f/2.8, introduced in 1971, has three floating elements to compensate for focusing aberrations at close range.