Lens Review: Nikkor 20mm f/2.8 AF-D
By John Cazolis
The following is a review I had written in early 1999 for the 20mm lens and it represents mainly my views in respect to shooting film (Velvia & Provia).
The field of view of this lens has always been favoured when shooting anything from landscapes to environmental portraits. Over the years I've had two Nikon samples go through my hands; the early AF version of 1989 and the later AF-D version of 1994. I've also used an old Ai-S version a few times that belonged to a friend and apart from the better feel of the MF version they all performed the same optically. I should add here that all three are of the same optical design that incorporates CRC technology, though I believe the AF-D version has a different and theoretically better multilayer coating, something that is hard to distinguish.
Supposedly the coatings of modern lenses are significantly better, resulting in less flare and higher contrast but for the majority of my shooting, I can’t really see a difference unless shooting a test chart in controlled conditions for comparison. This doesn’t mean all lenses are equal or that modern lenses are better, since some designs are not so great, due to their oversimplified design.
Today the Nikon AF 20mm f/2.8D is my favourite lens. Is it a better performer than the others? Well not exactly. When studying some of the slides taken with the above-mentioned lenses, there are no detectable differences. Optically I place them in the same performance category. I personally believe looking at some of my slides that the Nikon AF 20mm f/2.8D has much better contrast and better flare control resulting in richer colours, but this is just a feeling. I can’t see anything tangible to distinguish the three lenses optically.
I use this lens a lot and love it; it has performed admirably at all apertures except for the extremes. Now some people report distortion with this lens, but I honestly believe that they are referring to natural distortion due to perspective and not to the unwanted pincushion and barrel type of distortion, commonly found on most zooms and telephotos.
When facing a large square building the side closest to us will seem larger than the rear due to the natural laws of perspective. A wide-angle lens will only exaggerate this and the wider we go the more pronounced this effect will be. Parallel lines will seem to converge at some point in the far distance, and will be exaggerated even more if we tilt the lens. Most people don't comprehend the scale of this effect with the 20mm until they actually see their first photos. It does need some getting used too, so anything containing straight lines may warrant holding the camera in such a way as to keep the film plane vertical to the ground and parallel to the horizon.
With environmental portraits it is preferable to keep the lens at the same level as the faces and try to place them closer to the centre of the frame if we desire the least amount of perspective-distortion.
Becoming more critical, I did find something odd with the particular lens that I was using. The contrast was very good at f/2.8 & f/4 (quite unexpected) but at f/5.6 it consistently lost contrast (with all films and under different situations) and I can't explain why. This reminds me of what Jay Platter found when testing teleconverters on a Nikon 180mm f/2.8 ED-IF N (posted his findings on rec.photo.equipment.35mm).
At f/8 the 20mm f/2.8D gives the best contrast and at f/11 & f/16 it gives the best resolution especially when focused near, like 2m or 5m rather than INF. At f/22 there is a slight and noticeable drop-off in contrast as well as resolution which of course is due to diffraction but still better than f/5.6 (for this particular lens).
Obviously I will not be using f/5.6 with this particular copy of the lens and would welcome any comments and especially would love to hear if anybody else experienced the f/5.6 problem with the 20mm or any other lens for that matter. I will be using this lens at f/16 for those landscapes that require great D.O.F and maximum sharpness.
I also find it an excellent lens for environmental portraits wide open or at f/4, with good contrast and sharpness. Naturally there is some softening towards the corners of the frame though this is not noticeable unless you actually search for it and personally I think that it can be a plus in a lot of photos. Its quite obvious that someone that will be using this lens at f/2.8 or f/4 will not be shooting architecture or landscapes but most probably people, so some softness towards the corners is of no concern. Some pros are using this lens for architecture with great success and haven’t noticed any barrel distortion, though it does exist in a small dose towards the far edges of the frame. There are the usual converging verticals, but straight lines are always rendered as straight lines.
When using this lens wide open and photographing people up close, for best results I recommend manual focusing. I mention this because I find that manual focusing seems more accurate and easier. A friend shooting those types of shots wide open, with autofocus seems to always place that sharp line of focus in the wrong place resulting in a sharper shoulder in comparison to the face. Don't get me wrong, it isn't that noticeable with such a wide lens and at small enlargements but with shots that are taken wide open and printed large you can distinguish quite clearly that the sharp field of focus is anywhere but where the face is.
Groups/Elements: 9/12
Picture Angle: 94 degrees
Minimum f/stop: f/22
Closest Focusing Distance: 0,25m
Diaphragm Blades: 7
Maximum Reproduction Ratio: 1/8.3
Autofocus System: Std
Filter Diameter (mm): 62mm
Diameter x Length (mm): 69mm x 42.5mm
Weight (g): 270g
Lens Hood: HB-4
Notes: CRC
DOF when focused @ INF=
f/5.6 = 2.3m - INF
f/8 = 1.6m - INF
f/11 = 1.2m - INF
In production since: 1st:02-1989, 2nd: 03-1994
A sample of what the 20mm can produce
From memory probably shot this at 1/30 at f/16.
Although I am a big fan of tripod use and I strongly promote its usefulness I did not use a tripod for this shot. I was kneeling in the freezing wet snow with both elbows resting on knees for support.
John Cazolis
(aka Nikkor on Nikongear)
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Nikkor 20mm f/2.8D
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