Nikkor-UD 20mm f/3.5 Quick Review Nikon Nippon Kogaku
This is a large ultra-wide from the film days, which translates into a nice wide angle on APS-C. Does it get lost in translation?
Since this lens is for a 135 format film camera, it is fairly large for a wide angle on APS-C, especially when you add the adapter. The lens has 11 elements in 9 groups, and has an 7 slightly curved bladed diaphragm. The minimum focus distance is a short 0.3 m (1 ft), and is dense at 390 g (13.8 oz). Filter threads are 72 mm.
Comments on the Results
This lens performs acceptable for a wide angle lens, especially if you stop down. Center performance is great at all apertures, but corners aren’t good until around f/8. This lens performs maybe a bit better than the Sony 16mm f/2.8, but not a lot, and the Sony has a huge size and weight advantage.
Distortion is noticeable, but not extreme at -1.7% barrel (numeric average for all apertures).
Lateral CADifferent wavelengths (colors) of light have different magnifications and produce colored halos around high contrast objects near the frame edges. is not well controlled and is visible on shots.
ComaPoints of light are distorted near the edges of the frame. A circular point of light might be more comet shaped. is very noticeable wide open, and improves by f/5.6. AstigmatismDifferent angle edges have different focal points. A picture of an X might have one / of the X sharper than the other \. Has the appearance of slight motion blur or softness, and tends to be worst at the edges of the frame. is visible in the corners. The bokeh circles are oddly shaped near the edges wide open.
There is some purple fringingPurple fringing occurs around high contrast edges in a lens with high longitudinal CA in the focused areas; the slightly out of focus red and blue are fairly balanced and combine to create a purple halo. The sensor microlenses and color filter can aggravate purple fringing as well. wide open, but it is mostly gone by f/5.6.
Measured focal length at 1:53 magnificationHow large an image appears on the image sensor compared to how big it is in real life. Life size magnification means the image is the same size as the real object. My charts are photographed at 1:53 magnification, so if I photograph an area 53" wide it would appear as 1" wide on the sensor.: 22mm
Pros and Cons
- Center Performance
- Build Quality
- Corners/partway up until f/8
- ComaPoints of light are distorted near the edges of the frame. A circular point of light might be more comet shaped.