以下是许多中国发烧友熟知，也是美国当下最权威的尼康专家之一，KEN ROCKWELL对
尼康28MM镜头的评价。仔细阅读一下，你就会明白为什么28MM
是“尼康迄今制造过的最锐利的广角镜头”。
"Nikon 28mm f/2.8 AI-s on my Nikon FA. Click to enlarge.
This is Nikon's sharpest wide angle lens.
This is a spectacular and inexpensive lens. There is no sharper wide angle lens made by Nikon for SLR cameras, and it is the only Nikon wide angle, along with the 15mm f/3.5, that is completely free from barrel distortion at ordinary distances.
Optically this is almost a perfect lens and one of the most perfect lenses you can get to fit a Nikon camera.
Nikon let their designers go wild on this otherwise pedestrian seeming lens. Instead of a simple 5 element design that every other 28mm f/2.8 lens uses, including the original AF version, this lens has EIGHT elements in EIGHT groups. This allows it a level of correction seen in no other Nikon wide angle. Nikon wanted to show the optical world who was boss here.
Specifications
It has eight elements in eight groups.
It has close range correction (CRC), and believe it or not, focusses closer than any other Nikkor. It focuses down to 7 inches or 0.2 meters, which is closer than any of the macro/micro lenses. It does have some barrel distortion this close and remains sharp.
It takes the HN-2 hood, weighs only 9 oz. (250g) and is 2.5" (63mm) in diameter by 2.3" (59mm) long.
It has a seven-bladed diaphragm stopping down to f/22.
It takes the familiar 52mm filters.
Performance
It has no ghosts or flare, so feel free to put your light sources in your image.
It seems to be a bit slower than f/2.8, probably closer to about f/3.0. That's not a big deal; cheating a bit like that allows Nikon to squeeze in a little more sharpness.
Sharpness is extraordinary. There is some very slight coma in the corner at f/2.8 that is gone by f/4, far better performance than any other wide angle Nikkor wide open save the 28mm f/1.4D AF. The 28mm f/2.8 AI-s seems almost diffraction limited by f/5.6. That's lens designer speak for "really, really good!"
Here's the breakdown by aperture:
At f/2.8: sharp all over with the exception of very slight coma in the corners, some light falloff
At f/4: Fantastic, seems diffraction limited!
At f/5.6: Ditto. I've never seen a sharper lens on my Nikon.
Recommendations
This is the sharpest wide angle made for Nikon daylight photography. Not only that, but it seems you can get them used for $150 US and they work (manually focussed) on every Nikon camera, including AF. On some cheaper AF cameras you loose metering, but heck, mounted on your F4 or FA you even get matrix metering. New they go for $360 US.
This AI-s lens (1981-present) is completely different from the older AI lens (made 1974-1981) which I have not tried. Nikon made a big upgrade to this lens' optics when they upgraded it to AI-s, and they really pulled out all the stops. No other Nikon 28mm lens performs this well: the 28mm f/1.4D AF has some barrel distortion and really is optimized for night photography, and every other 28mm lens just isn't designed as thoroughly. The Series E lens was only a common 5 element design, and the AF and AF-D versions are the same as the Series E design. In 1998 Nikon introduced a 6 element 28mm f/2.8 AF which I have not tried, but have read elsewhere is quite good.
If you want great sharpness and perfectly straight straight lines, go get one of these lenses new or second hand. You'll love it, presuming you get a good sample.
引自：
http://www.kenrockwell.com/nikon/28f28ais.htm
