Monday, December 13, 2010

First Impressions: AF NIKKOR 20mm f/2.8D

I finally received my Nikkor Ultrawide prime today. I’ve been debating this purchase for a while now, but if I’m going to have at least one AF-D lens in my collection, it might as well be the most compact of them all and be compatible with a wide variety of bodies and uses.

It seems that, for a lens of this price range, a pouch should have been included. It was conspicuously absent from the box, as was the bayonet lens hood. But then, this is a different class of lens altogether.

First off, this lens is made in Japan. Not that I feel that products manufactured in Thailand, Korea or China are of poor quality. But this lens is made in Japan.

Secondly, it’s fully mechanical, not electronic. Yes, it has a chip to tell the camera what type of lens it is, and to relay the focus distance information for 3D matrix metering, but that’s it. When you look inside the focus scale window, you see a metal focus scale with etched, paint-filled numbers, directly coupled to the rubber-covered focus ring. This direct coupling makes all the difference. It gives the focus a silky-smooth feel with hard stops at 0 and infinity. Silky smooth, but not damped. Damping the lens would interfere with its autofocus operation, so it’s the first thing to go. But this lens is, for all intents and purposes, a traditional lens.

I like the simplicity of the older autofocus system. A simple mechanical linkage, driven by the camera, simplifying the lens. I can see now why this lens is as compact as it is. But, I can also hear the case for the built-in Silent-Wave motor. This lens is L-O-U-D. Fast, but loud. When traveling from one extreme to another, you can really hear it go. But, that’s not particularly field-relevant, because in actual use, the travel is usually quite short, emitting just a brief chirp.

This lens give new purpose to the two-position AF-M switch at the base of the lens. Doesn’t do much with a G lens. But with a D lens, it decouples the focus linkage, allowing fully manual focusing, as well as electronically disabling the motor.

Sadly, this is the worst mounting of all my lenses. It goes on with all sorts of grinding sensations, although I  can find no physical evidence as to why. But, once it’s on, it fits nice and tight, with no play whatsoever. The body of the lens just barely provides enough surface area to grip it while mounting. I would definitely NOT recommend using the focus ring’s infinity stop to aid in this operation, although I would think the f/22 lock on the aperture ring would be OK. The additional surface area of the aperture ring definitely helps.

It’s a good idea to decouple the focus linkage using the AF-M switch before mounting any D lens. If you do accidentally slip and turn the focus ring, it won’t turn the motor and gearing in the camera.

On the D90, it looks and feels great. Proportionally it’s just right, although it would dwarf a D40 or D60, and on a D3 it would just about hold its own. Its outward taper gives it a solid, professional look, and its short focal length makes it compact and easy to focus. A lens you don’t mind keeping on your camera at all times. Tricky to keep your hand off the focus ring in autofocus mode, but the body is long enough to grip if you like to steady the camera that way.

The field of view is perfect on the D90. At a full-frame equivalent of 30mm, it falls between that golden 35mm, and the superwide 24mm, very usable indeed. Actually, the diagonal measurement of the APS-C sensor is 30.5mm making this a true “normal” lens, just as 43mm is on a full-frame camera. The DX crop factor uses the most accurate part of the lens’ field of view, so the edges are sharp and free of any noticeable aberrations.

To be honest, I don’t see myself owning a lot of D lenses, so If I only have one, this seems to be a good choice. If the impeccable Nikkor AF-S DX 35mm f/1.8G wasn’t 1-1/3 stops faster and so darn cheap, I’d probably forgo it for this lens.



Tech Notes:
  • The 20mm f/2.8D has a bayonet lens hood mount, which accepts the Nikon HB-4 Bayonet Lens Hood.
  • On the D90, the Hoya 67mm adjustable lens hood can be used in its intermediate position with a 62-67mm step-up ring.
  • On a full-frame camera such as the N80, neither the 67mm nor the larger 72mm Hoya adjustable hood can be used even at their widest settings without minor vignetting.



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