Maker | Minolta |
---|---|
Technical data | |
Focal length | 21mm |
Features | |
Ultrasonic motor | No |
Macro capable | No |
Physical | |
Filter diameter | Integrated |
Accessories | |
Lens hood | Integrated Flower |
Angle of view | |
Diagonal | 92° |
History | |
Introduction | 1962 |
Discontinuation | 1977 |
Successor | W Rokkor 20mm f/2.8 |
The W Rokkor 21mm lenses are a series of three prime wide angle lenses produced by Minolta for Minolta SR-mount single lens reflex cameras. 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. This was succeeded by the W Rokkor-QH 21mm f/4 (1963), with slightly improved speed and similar symmetric construction. 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.
Minolta updated the design several times during the course of production; the first two versions were symmetric designs which required the reflex mirror to be locked up, while the third version was a retrofocus design, followed by a cosmetic update in 1973.[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".[2] The similarities in lens design between the Biogon and the Rokkor-PI f/4.5 have led to speculation the latter was discontinued in favor of the Rokkor-QH f/4 in response,[3] as the -QH shares a similar 8-element, 4-group design as the Nikkor-O 2.1cm f/4 (1959).[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).[5] By 1968, the successor Rokkor-QH f/4 retailed at a lower price, US$159.50 (equivalent to $1,400 in 2023), with a dealer cost of US$95.70 (equivalent to $840 in 2023).[6]
The Rokkor-NL f/2.8, introduced in 1971, has three floating elements to compensate for focusing aberrations at close range.[7][8] It was replaced by the MD Rokkor 20mm f/2.8 lens (1977), which was more compact and lighter.[9]: 74
Model Spec
|
W Rokkor-PI 21mm f/4.5 | W Rokkor-QH 21mm f/4.0[10] | MC W Rokkor NL 21mm f/2.8[11]: IV-47 | MC W Rokkor(-X) NL 21mm f/2.8[12] | |
---|---|---|---|---|---|
Year | 1962 | 1963 | 1971 | 1973 | |
Construction | Elements | 9 | 8 | 12 | |
Groups | 5 | 4 | 9 | ||
Aperture | f/4.5–16 | f/4.0–16 | f/2.8–16 | ||
Min. focus | 0.9 m (35.4 in) | 0.25 m (9.8 in) | |||
Metering features | Meter coupling (MC) tab | No | No | Yes | Yes |
Minimum diaphragm (MD) tab | No | No | No | No | |
Aperture lock | No | No | No | No | |
Dimensions | Diam. | 60 mm (2.4 in) | 75 mm (3.0 in) | ||
Length | 20 mm (0.8 in) | 67 mm (2.6 in) | |||
Weight | 170 g (6.0 oz) | 166 g (5.9 oz) | 510 g (18 oz) | ||
Filter (mm) | 55 | 72 |
The 21-mm MC W-Rokkor-NL f/2.8 has three floating elements in its front section that move about 2-mm when the lens is focused between infinity and 10 in. Probably the fastest lens of its focal length to date, this 21-mm f/2.8 has 12 elements, half of which are stated to be special rare-earth types.
General | |
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SR-mount cameras | |
SR-mount lenses | |
A-mount cameras | |
A-mount lenses |
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