Additional Information on
Pre-AI version of the Nikkor 20mm Ultra-Wideangle Lens

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Non-Ai 20mm f/4.0 Nikkor-Auto


Images of this Non-Ai Fisheye-Nikkor 20mm F4 coutesy of:

Emanuele "ebay-camera$®" <> who operates a popular Ebay Store. All images appeared herein are Copyright © 2003. All rights reserved. Please respect the visual property of the contributing photographer.

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Unlike conventional lenses which usually have their next upgrade came with faster lens speed, here was an exception. Superseding the earlier Nikkor 20mm f/3.5 UD lens, the next Nikkor 20mm upgrade lens was indeed has a slightly slower speed maximum aperture at f/4.0. This version was introduced in November, 1974. It was developed primarily with an objective to ensure it was compact in size and light in weight. The 94' picture angle of this lens is supplemented with the use of an optical formulation of 10 elements in 8 groups design and with thru-the-lens operating convenience. The Nikkor 20mm f/4.0 accepts 52mm screw-in lens accessories due to its drastic reduction in the overall size of the lens as compared to previous f/3.5 UD non-AI lens which has a filter attachment size of 72mm.

General optical aberration found in extreme wideangle lenses such as Coma has been restricted to absolute minimums, ensuring sharp images without the deterioration in contrast which is likely to occur with retrofocus type lenses. For reduction of flare and ghost, NIC was applied to air to-glass lens surfaces. With its wide coverage and great depth of field, this lens, like the 15mm and 18mm lenses, is especially useful for shooting in constricted areas, in wide expanses of nature, for snapshots, and for dramatic and creative pictorial effects.

Credit: Images of this Non-Ai Fisheye-Nikkor 20mm F4 coutesy of: Russell Gough® <>" All images appeared herein are Copyright © 2003. All rights reserved. Please respect the visual property of the contributing photographer.

As with similar optical nature in other Nikkor ultrawides lenses, the 20mm f/4 has a wide focusing latitude due to its great depth of field and thus, there is generally little need for refocusing when the lens is used even slightly stopped down. When used in combination with the Nikon Bellows Focusing Attachment and the BR-2 Macro Adapter Ring, this lens will provide up to an amazing 12X magnification - which is highest ratio among all Nikkor interchangeable lenses. This lens has an equivalent Ai version here it has been updated with an AI coupling system in March, 1977. Both earlier Non-Ai and the subsequent Ai version share similar optical design. Interesting enough, prior to the availability of the Ai f/4.0 20mm lens, Nikon showcased an extremely fast Non-Ai Nikkor 20mm f/2.8 prototype during photokina, 1976 but it has never been surfaced nor marketed.

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<<<<<< --- Credit: Mr. Charles Daly <> for his images of Nikkor 20mm f4.0

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Download an Optical Construction file in new browser window: 22k Gif; Nikon guide to compatible focusing screen(s) selection, close-up attachment and Depth of Field calculation chart for this 20mm Ultra-wideangle lens. Download a file in a new browser window 104k.Gif

Credit: Images of this Non-Ai Fisheye-Nikkor 20mm F4 coutesy of: Russell Gough® <>" All images appeared herein are Copyright © 2003. All rights reserved. Please respect the visual property of the contributing photographer.


Focal length:
Maximum aperture: 1:4.0
Lens construction: 10 elements in 8 groups
Aperture Scale: f/5.6 ~ f/22
: Fully automatic
Lens Coating: Multicoated with NIC
Picture Angle: 94
Distance Scale: Graduated in meters and feet from 0.3m (1ft.) to infinity (
OO); infrared index is provide.
Exposure Measurement: via full aperture method; meter coupling prong provided
Meter coupling prong: Integrated (fully open exposure metering)
Attachment size: 52mm (P=0.75mm)

Lens hood: HN-14 (Optional)
Filters: 52mm Screw-in
Lens Mount: Nikon bayonet mount
Dimensions: 63.5mm dia. x 47.5mm long
Weight: 210g
Images of this Non-Ai Fisheye-Nikkor 20mm F4 coutesy of: Emanuele "ebay-camera$®" <> who operates a popular Ebay Store. All images appeared herein are Copyright © 2003. All rights reserved. Please respect the visual property of the contributing photographer.

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Accessories Supplied: Rear protective cap LF-I (108-00-401); 52mm Snap-On front lens cap (108-00-400);
Optional Accessories: 52mm screw-in lens hood HN-14 (108-01-205); Soft lens pouch No.54 (108-00-319); Hard lens case CL-31 with strap (108-00-308); 52mm screw-in filters; Close-up attachment lenses; plastic lens case CP-1 (108-00-300); Gelatin filter holder AF-1 (108-00-700).

Nikon Product Code for this discontinued item is No.108-01-128; Content appeared in this section is largely extracted from Nikon Sales Manual, 1974/1976;
Note: Starting serial number for this lens was believed to have been started with 103001 while the Ai version that followed started from 130001

Some basic information relating to this rare Rangefinder Lens, 2.1cm f/4 Nikkor-O (Compared this with the reflex lens version debuted along with the Nikon F in 1959)

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Introduced: June 1959; Apertures: f/4.0-f/16; Angle of View: 92 degrees; Elements: 8 in 4 groups; Focusing range: 1m to infinity; Filter size: 43mm; Weight: 4.5 ounces.

UPDATED: Nippon Kogaku KK / Nikon's NIKKOR-O 1:4 f=2.1cm Rangefinder lens

Although the lens was used to be the widest of all the RF Nikkors for
Nikon rangefinder camera series, the 21mm f4.0 Nikkor-O was also one of the last rangefinder lens to be introduced. It was announced at the same Exhibition that saw the introduction of the Nikkor 50mm f/1.1 lens with external bayonet mount, the 350mm and 1000mm short mount lenses. Because due to its limited short run in production of less than 2 two years until 1961 when Nikon shifted its attention and marketing to SLR reflex photography. The lens was also being converted for the reflex SLRs with an Identical optical formula with the RF version. However, the auxiliary finder for the rangefinder camera is not interchangeable with the reflex lens version.

| Back to Main Index Page of Nikkor 20mm ultra-wideangle lenses |

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Dedicated Lenses for Nikon F3AF: AF 80mm f/2.8 | AF 200mm f/3.5 EDIF
Depth of Field Control (DC): 105mm 135mm
Medical Nikkor: 120mm 200mm
Reflex-Nikkor Lenses - 500mm 1000mm 2000mm
Others: Noct Nikkor | OP-Nikkor | UV Nikkor 55mm 105mm | Focusing Units | Bellows-Nikkor 105mm 135mm
Nikon Series E Lenses: 28mm35mm50mm100mm135mm | E-Series Zoom lenses: 36~72mm75~150mm70~210mm

MF Zoom-Nikkor Lenses: 25~50mm | 28~45mm | 28~50mm | 28~85mm | 35~70mm | 36~72mm E | 35~85mm | 35~105mm | 35~135mm | 35~200mm | 43~86mm | 50~135mm | 50~300mm | 70~210mm E | 75~150mm E | 80~200mm | 85~250mm | 100~300mm | 180~600mm | 200~400mm | 200~600mm | 360~1200mm | 1200~1700mm

Tele-Converters: TC-1 | TC-2 | TC-200 | TC-201 | TC-300 | TC-301 | TC-14 | TC-14A | TC-14B | TC-14C | TC-14E | TC-16 | TC-16A | TC-20E

Recommended links to understand more technical details related to the Nikkor F-mount and production Serial Number: by: my friend, Rick Oleson by: Hansen, Lars Holst

Recommended Reading Reference on Nikon cameras and Nikkor lenses | about this photographic web site

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leofoo.Gif Co-developed with my web buddy, Rick Oleson® & LARs.Gif Denmark, Creator of the Nikon Repair Group Mailing-List; A contributing effort to Michael Liu's Classic Nikon SLRs and Nikkor optic site.

Credit: MCLau®, who has helped to rewrite some of the content appeared this site. Chuck Hester® who has been helping me all along with the development of all these Nikon websites; Lars Holst Hansen, 'Hawkeye' who shares the same passion I have; Ms Rissa, Sales manager from Nikon Corporation Malaysia for granting permission to use some of the official content; Ted Wengelaar, Holland who has helped to provide many useful input relating to older Nikkor lenses; Some of the references on production serial numbers used in this site were extracted from Roland Vink's website; Hiura Shinsaku from Nikomat Club Japan. Lastly, to all the good people who has contributed their own expeience, resources or kind enough granted permission to use their images of their respective optic in this site. It is also a site to remember a long lost friend on the Net. Note:certain content and images appeared in this site were either scanned from official marketing leaflets & brochures published by Nikon and/or contribution from surfers who claimed originality of their work for educational purposes. The creator of the site will not be responsible for may discrepancies arise from such dispute except rectifying them after verification. "Nikon", "Nikkormat", "Nippon Kokagu KK" & "Nikkor" are registered tradename of Nikon Corporation Inc., Japan. Site made with an Apple IMac.