WHAT IS IT GOOD FOR
As I've already mentioned, the 20mm is really useful for a lot of things: Landscape (no surprise), environmental portraits and even action photography. There's a tendency in the industry to get more wide angled and lots of pros are using both wide primes and the great 17-35 zooms to allow them to get really wide. The latest AF 14mm/2.8D prime Nikkor is a par example of this trend.
The build quality of the lens is OK. I am not overly enthusiastic, but it feels OK. Maybe my somewhat negative feelings have to do with the low weight of it, fooling me to draw false conclusions while comparing it to the 80-200mm f/2.8D ED IF AF glass monster.
To reduce flare, I use the HB-4 hood at all times. A little hard-plastic thingy coming in all black making the lens some 89mm wide in all. As with nearly all hard Nikon hoods, it fits perfect, twisted some 15 degrees onto the front bayonet. Due to the wide angle of this lens, I wouldn't recommend you using it without the HB-4.
The focus ring is rubber covered and moves gently. According to my Preisser digital Digi-Met measuring device, the lens extends 1.88mm when moved from eternity focus to 0.25m.
The aperture can be locked at F22 using the well known slide-lock existing on most AF Nikkors. The aperture markings are: 2.8, 4, 5.6, 8, 11, 16 and 22 so there are no surprises here either.
Peeking into the front of the lens, you're confronted with a protective piece of glass which covers a pretty small, convex lens not much wider than 23 mm in diameter (again, according to Preisser). This is a huge disturbance for someone who's used to "lots of glass and not much of black metal". The image reproduction quality of this lens is then relying on the correct distribution of light through this silly little opening.
Despise the weak look, I have gotten a whole bunch of good shots using this lens and I wouldn't like to live without it.
Vignetting is not visible, as long as you're not underexposing a piece of white cardboard. Color reproduction and the sharpness are great. Regarding "Bokeh" - well, to be honest I have no idea, but I guess there are better lenses for "Bokeh" (the nifty look of out-of-focus areas).
My sample seems to have a tad of a problem at the edges when used fully open - the edges are then not really sharp when studied carefully. I believe this to be an anomaly of the sample I have and not a general problem (remember, I bought it at eBay - there was most definitely a reason why the lady was so friendly)
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