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Nikon 20mm f/2.8
NIKKOR AI-s (1984-today)

© 2012 KenRockwell.com

Intro    Specifications    Performance   Compared   Recommendations

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Nikon 20mm f/2.8 AI-s

Nikon 20mm f/2.8 AI-s (62mm filters, 9.1 oz./259g, about $650 brand new or $350 used.) enlarge. This free website's biggest source of support is when you use any of these links, especially this direct link to this lens at B&H or this link directly to them at eBay (see How to Win at eBay), when you get anything, regardless of the country in which you live. Thanks! Ken.

March 2012, September 2010   More Nikon Reviews   Nikon Lenses   All Reviews

How to Use Ultrawide Lenses

Sharpness Comparison to other 20mm lenses

20mm lens falloff comparison

Zeiss 21mm Comparison


Ideal Uses

Superb FX ultrawide, and compact, too. Nikon has never made a faster 20mm lens, and this lens is smaller and lighter than any Nikon ultrawide zoom.


Not for

I wouldn't bother with this on a DX camera. I'd use any DX lens, like the 18-55mm kit lens, instead. As a manual focus lens, I wouldn't use it for sports, kids or action since it's too hard to track focus by hand.


Ergonomics: (manual focus)


Sample Images

Best Western Casa Grande, Arroyo Grande

Best Western Casa Grande, Arroyo Grande, 9:52 PM, 12 April 2013. bigger. (1977 Nikon EL2, 1990 Nikon 20mm f/2.8 AI-s with no filter, Fuji Velvia 50, f/5.6 at two seconds hand-held while sitting in a comfy chair, process and scan at NCPS, Perfectly Clear.)

Madonna Inn, San Luis Obispo.

Stairs, Madonna Inn, San Luis Obispo, 10:26 AM, 11 April 2012. bigger. (1977 Nikon EL2, 1990 Nikon 20mm f/2.8 AI-s, Nikon A2 (81A) filter, Fuji Velvia 50, f/2.8 at 1 second hand-held (I braced myself on a railing), process and scan at NCPS, Perfectly Clear.


Introduction     top

Intro    Specifications    Performance   Compared   Recommendations

Compatibility    History

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This has been Nikon's most popular manual focus 20mm lens since the 1980s. Nikon still makes them in 2012, and you can buy them brand-new from B&H Photo-Video.

As all of the Nikkor AI-s manual focus lenses, this Nikon 20mm f/2.8 lens represents the highest standard of mechanical precision and durability that Nikon has ever attained.

Nikon also makes this same lens in an autofocus version, the 20mm f/2.8 AF (1989-1994) and 20mm f/2.8 AF-D (1994-today). It uses identical optics in a plasticy package.


Compatibility       intro     top

The manual-focus Nikon 20mm f/2.8 works great with most Nikon cameras, 35mm and digital.

It works flawlessly with every manual focus Nikon ever made, from the F of 1959 through the FM3a and today's FM-10.

On the D4, D800, D800E, D7000, D3X, D3s, D3, D700, D300, D200, D2, F6 and others, use the "Non-CPU Lens Data" menu option to set 20mm and f/2.8 to get full color matrix metering, EXIF data and finder read-out of set aperture. It works great in aperture-preferred as well as manual modes on these cameras.

It works perfectly on every professional 35mm camera (F, F2, F3, F4, F5, F6), and adds Matrix metering on the FA, F4 and F6.

The meters of cheaper digital (D90, D5000 and below) and cheaper film cameras (N80 and below) will not couple (or work at all) with this lens, so you'll be on your own guessing exposure using the rear LCD or an external meter, or get a tiny Gossen Digisix meter and hot shoe adapter to meter manually.

See Nikon Lens Compatibility for details on your camera. Read down the "AI, AI-s" column for this lens.


Nikon 20mm f/2.8 AI-s

Nikon 20mm f/2.8 AI-s. enlarge.


Nikon 20mm History        intro       top



Nikon repackaged their 2.1cm (21mm) f/4 rangefinder lens, originally designed for the Nikon SP, for the F-mount SLRs.

It required the use of mirror lockup and a separate finder slid over the funky rewind crank of the NIkon F, as it poked all the way into the camera.

Nikon made about 5,000 of the 2.1cm f/4 lenses.



The 20mm f/3.5 UD was Nikon's first 20mm lens. It was the ultrawide for the late 1960s and early 1970s. There was no wider non-fisheye lens made by Nikon until the insane 15mm f/5.6 of 1973 and the 18mm f/4 of 1974.

Nikon made about 40,000 of the 20mm f/3.5 UD lenses.



The tiny 20mm f/4 (52mm filters), the smallest ultrawide ever made by Nikon or Canon, replacing the big 20/3.5 UD, with similar optical performance.

In 1975 Nikon introduced the world's widest non-fisheye lens, the Nikkor 13mm f/5.6, which remains today a the world's widest professional SLR lens ever made.

Nikon made F-mount (non-AI) 20mm f/4s from 1974-1977. The mount was redesigned as an AI lens in 1977, and sold until 1978.

Nikon made about 35,000 of these 20mm f/4 lenses, about half AI and half not. Most non-AI lenses have long since been updated to AI.



The 20mm f/3.5 AI lens was introduced in the fall of 1977 as one of the first AI lenses.

The optically identical AI-s version replaced it in the fall of 1981. The AI-s version was made until about 1984, since most people preferred the f/2.8 and bought it instead.

Nikon made about 30,000 of each version, or 60,000 total.



Nikon replaced the tiny 20mm f/3.5 with this 20mm f/2.8 in 1984. It takes 62mm filters and is sold today in both this manual-focus AI-s version and autofocus versions.

Nikon has made about 70,000 of the 20mm f/2.8 AI-s lenses as of 2010, and still makes them today.

Nikon has made about 115,000 of the 20mm f/2.8 AF and AF-D lenses as of 2010, and still makes them today.


Specifications    top

Intro    Specifications    Performance   Compared   Recommendations


Nikon calls this the Nikon NIKKOR 20mm f/2.8 AI-s.


Optics     top

12 elements in 9 groups.


Close-range correction (CRC) floating elements.


Focal Length     top


Used on a DX camera it gives angles of view similar to what a 30mm lens would give on an FX or 35mm film camera. See also Crop Factor.


Angle of View        top

94° on FX and 35mm.

71° on small-format DX.


Diaphragm     top

7 blades.

Stops down to f/22.


Close Focus     top

0.85 feet (0.25m).


Maximum Reproduction Ratio     top



Depth-of Field Scale     top



Infra-Red Focus Index     top

YES, near the f/5.6 depth-of-field index.


Filter Thread     top



Does not rotate.


Size     top

1.669" extension from flange by 2.559" diameter (42.40 x 65.00mm), measured.

Nikon specifies 42.5 x 65mm.


Weight     top

9.125 oz. (258.75g), measured.

Nikon specifies 260g.


Hood     top

Nikon 20mm f/2.8 AI-s

Nikon 20mm f/2.8 AI-s and HK-14 slip-on hood. enlarge.

The 20mm f/2.8 takes the HN-14 slip-on hood.

It holds-on by tightening the thumb screw.


Nikon Catalog Number     top



Price, USA     top

March 2012: about $675 new at B&H, $675 at Nikon, or $350 at eBay.

September 2010: about $600 new at B&H, or $675 at Nikon.


Performance    top

Intro    Specifications    Performance   Compared   Recommendations

Overall   Focus    Color    Coma    Distortion   Ergonomics

Falloff    Filters    Ghosts   Color Fringes

Mechanics    Sharpness   Sunstars



Optically it's a typical Nikon wide-angle: soft in the corners wide-open due to coma, and some light falloff that goes away stopped down.

The barrel distortion is a little more complex than usual: the center of the image has the usual barrel distortion, however it starts to straighten out at the far edges. This makes it measure a little better in tests, but also makes it much more difficult to correct in Photoshop.

Performance is great; used properly, it's sharp and just works.

The only sharper 20mm Nikon lenses are either the 16-35mm or 14-24mm, and then only if you look in the corners at f/4 and f/2.8.

All Nikon's previous 20mm lenses are just as sharp, and oddly also have the same falloff and distortion.


Focus      performance     top

Manual focus has the exquisite classic Nikon feel, which is duplicated nowhere else.

One light fingertip is all that's required to focus.

Focus is fast. It goes from infinity to 0.85 feet (0.25 meters) in only 90º of rotation.


Color Rendition      performance     top

Like all Nikon multicoated lenses, I've never seen any variation between any of them in color rendition. They all look the same, the hallmark of a well-designed lens line.

Peripheral color balance is cooler than the center, which is typical for ultra-wide lenses of every brand and format.

I can't see this in real photos, but you will see it in photos of white walls. If it bothers you, get the 14-24mm f/2.8 AFS, which has this effect under better, but not complete, control.


Coma      performance     top

The 20/2.8 has plenty of saggital coma flare (points of light turning into weird blobs in the corners) at f/2.8, less at f/4, and it's gone by f/5.6.


Distortion      performance     top

La Jolla Coastline

La Jolla Seashore, on FX, uncorrected. Note slight wiggling along top. enlarge.

Distortion is complex on film and FX.

It's simple barrel distortion on DX, with no wiggling.

You may as well leave it along on film and FX, since the correction below doesn't do much to eliminate the complex curve.

On DX, it corrects perfectly, but why use this 20mm lens on DX when the 18-55mm AFS kit lens works so much better?

Plug these figures into Photoshop's lens distortion filter to correct the distortion. These aren't facts or specifications, they are the results of my research that requires hours of data collection and computation.

FX and Film
3m (10 feet)

© 2008 KenRockwell.com

*Wiggling, or waviness, remains.


Ergonomics      performance     top

Nikon 20mm f/2.8

Nikon 20mm f/2.8 AI-s. enlarge.

The Nikon 20mm f/2.8's ergonomics are perfect: just one big focus ring, a head to keep your fingers out of your pictures, and a grip and aperture rings at the back.



Falloff (darkened corners)          performance     top

Falloff is visible at f/2.8, mostly goes away at f/4, and is gone by f/5.6.

Falloff on FX is exactly the same as Nikon's other 20mm lenses and wide zooms.

It won't be an issue at all on DX (see crop factor).

I've exaggerated this by shooting a gray field and placing these on a gray background.


Nikon 20mm f/2.8 AI-s falloff on FX and film at infinity, no correction.


© 2010 KenRockwell.com. All rights reserved.




Filters, Use with      performance     top

There is no problem with vignetting with 62mm filters, so long as you use Nikon brand or other filters which have very thin mounts.

The very thick mounts of most Tiffen, Heliopan and B&W filters may cause some vignetting on film and FX digital, especially with rotating filters.

I use a 62mm -> 77mm step-up ring and 77mm filters, with which the vignetting problem goes away.

Don't use a polarizer; they don't work with well with any 20mm lens because the polarization of nature itself varies over such a broad angle.


Flare and Ghosts      performance     top

With the disc of the sun in the image, there may be a stream of green ghosts across the image.


Lateral Color Fringes      performance     top

There are no lateral color fringes on the 12 MP D3, or 24 MP D3X, which would correct them if the lens had any.


Mechanics      performance     top

Nikon 20mm f/2.8

Nikon 20mm f/2.8 AI-s. enlarge.

Like all Nikkor manual focus AI-s lenses, the Nikon 20/2.8 AI-s is built to the highest mechanical standards, unlike the dinky plastic AF-D version more popular today.


Barrel Exterior

Anodized and enameled aluminum.


Filter Threads

Anodized aluminum.


HK-14 Hood

Anodized aluminum, painted markings.


Focus Ring

Metal, rubber covered.


Focus Helicoids

Feels like brass: smooth and silky with no play or need for damping grease.


Depth-of-Field Scale

Engraved into barrel and filled with different colors of paint.



All metal.


Aperture Ring

Cast aluminum, anodized and enameled.

Engraved markings filled with different colors of paint coded to the depth-of-field scale.



Dull-chromed brass.



Engraved into the metal and filled with paint.


Identity and Serial Number

Engraved at the front, outside the filter ring, and filled with paint.


Ass-Gasket (dust seal at mount)



Noises When Shaken

Some clucking from the sections of the CRC system floating around.


Made in



Sharpness      performance     top

Warning 1: Image sharpness depends more on you than your lens.

Warning 2: Lens sharpness doesn't mean much to good photographers.

The 20/2.8 AI-s is super-sharp on a 24MP FX D3X when used properly (stopped-down). It's softer at f/2.8, so don't shoot it there if you're counting pixels.


On a 24MP FX Nikon D3X


At f/2.8

Everything is a little soft and dreamy, veiled by spherical aberration.

The corners show a healthy dose of coma.


At f/4

The spherical aberration is gone from the center, which is now sharp and contrasty.

The sides and corners are softer, and the corners show coma.


At f/5.6

The sides perk right up, and are now sharp and contrasty.

The corners are still softer.


At f/8

The corners improve further, and the center is optimum at f/8.


At f/11

The corners are optimum at f/11, while diffraction only slightly reduces center sharpness.


Sunstars      performance     top

With its classic 7-bladed diaphragm, the 20mm f/2.8's classic 14-pointed sunstars on bright points of light.


Compared        top

Intro    Specifications    Performance   Compared   Recommendations

Oddly, I carefully compared this to eight other Nikon fixed 20mm and ultrawide zooms, and except for the superior 16-35mm and 14-24mm, they all have pretty much the same sharpness overall!

I compared the 20/3.5 UD, 20/4 AI, 20/3.5 AI, 20/2.8 AI-s, 20/2.8 AF, 20-35mm, 17-35mm, 18-35mm and 14-24mm. Wow! Yes, they were all different, but different in different ways in different places, thus in all, they were each as sharp as the next. (The 16-35mm and 14-24mm were superior, but everything else was the same.)

Sharpness Comparison to other 20mm lenses

20mm lens falloff comparison

Zeiss 21mm Comparison

23.9 oz.
7.040 oz.
9.1 oz.
8.2 oz.
7.4 oz.
13.7 oz.
Price, USA,
September 2010


Recommendations       top

Intro    Specifications    Performance   Compared   Recommendations

This 20/2.8 AI-s lens is much more sturdily and precisely built than its optically-equivalent AF cousin.

You could save money and get an AF version for use on your manual focus camera if you don't mind the AF lens' sloppier mechanics.

I have seen no major difference in optical performance (sharpness, falloff or distortion) among any of Nikon's fixed 20mm lenses.

The autofocus 20mm can have sloppier corner performance than this AI-s lens due to the sloppy mechanics of the AF version; just try to wiggle the front of an AF and this AI-s lens and you'll see how sloppy is the AF lens by comparison.


Deployment     top

I'd pitch the flat Nikon cap that came with these lenses made before about 2008, and get a new 62mm "pinch" type cap. I'm not kidding: the new fatter caps are much easier to use in the field.

I'd leave either a 62mm Nikon Clear (NC - UV) filter, or a 62mm Hoya Super HMC UV on the lens at all times.

For color slides like Velvia 50, I use a 62mm Nikon A2 or a 62mm Hoya HMC 81A outdoors.

For B&W film outdoors, I'd use a 62mm Nikon Y48 or 62mm Hoya HMC K2 Yellow, or 62mm Nikon O56 or 62mm Hoya HMC Orange.

For integration within a larger professional Nikon system, I use a 62mm -> 77mm adapter ring, and treat this as 77mm lens for the sake of my own sanity. If you do, too, forget 62mm filters and caps, and:

Get a new 77mm Nikon front cap.

I'd leave either a 77mm Nikon Clear (NC - UV) filter, or a 77mm Hoya Super HMC UV on the lens at all times.

If I was working in nasty, dirty areas, I'd forget the cap, and use an uncoated 77mm Tiffen UV filter instead. Uncoated filters are much easier to clean, but more prone to ghosting.

For color slides like Velvia 50, I use a 77mm Hoya HMC 81A or Nikon A2 filter outdoors.

For B&W film outdoors, I'd use a 77mm Hoya HMC Yellow K2 or 77mm Hoya HMC Orange.


Help me help you         top

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Mr. & Mrs. Ken Rockwell, Ryan and Katie.

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