Nikkor Z 28-400mm f/4-8 VR Resolution Analysis

What follows is a comprehensive resolution analysis of Nikon’s 28-400 Z-mount zoom lens. Lens resolution is quite a nuanced subject. There is no such thing as “center resolution” or “edge resolution” reduced to a single number. You can’t even define ‘the’ resolution at a single point.

Resolution of optics is a three-dimensional topic, but even three dimensions aren’t sufficient to fully define resolution. To really understand how sharp a lens is, resolution measurements are divided into both sagittal and meridional directions. The sagittal direction can be described like wheel spokes, while the meridional direction is similar to the rim of a wheel. Lens resolution can also affected by the focus distance.

I use the free MTFMapper program for resolution analysis, which enables a level of thoroughness that really lets you understand the resolution characteristics of a lens. I photograph a special chart that has the fairly large dimensions of 40” X 56” (102cm X 142cm). A large chart like this enables photographing at much more realistic distances, while still providing information across the entire field of view.

My resolution photographs are made using ‘raw’ format, with no sharpening applied to them. Don’t trust any web sites that use jpeg, tiff, etc. for their resolution tests, since these formats all have some level of sharpening applied. Sharpening a photo ruins any resolution analysis of it; the measurement results become meaningless.

If you want to use the Nikon ‘high efficiency’ compressed raw formats, called ‘HE Raw’ and ‘HE* Raw’, then they will need to be converted into the DNG raw format before using MTFMapper. The Adobe DNG Converter program used to convert raw formats into the DNG format is free and can be downloaded from the Adobe web site. DNG is an abbreviation for “digital negative”.

Beyond the lens resolution characteristics, you also have to know which camera the lens is attached to. This is because you have to know about the dimensions and pixel size of the camera sensor. For the test results that follow, I used both the Nikon Z9 and Z8 cameras which have identical sensors. The Z8/Z9 sensor is 35.9mm X 23.9mm. The number of useful pixels is 8280 X 5520 or 45.7 MP. Each pixel is 4.35 microns. This information is provided to the MTFMapper software for the resolution calculations, which I will provide in units of MTF50 lp/mm.

I like to report resolution units of MTF50 lp/mm (line pairs per millimeter), in order for people with different camera sensors to compare the results. Web sites that give resolution numbers in units such as “lines per picture height” are meaningless if you don’t know the size of the camera sensor and its pixel dimensions used to take the photographs.

I skip any measurements beyond f/16, because diffraction ruins the resolution. Use f/22 and beyond only when you don’t care about sharpness. Even f/16 is pretty bad for resolution.

Finally, I use the best results from typically10 photographs of my resolution chart at a given focal length and distance. I re-focus the lens before each chart photograph. I use a wired remote release to minimize any vibrations. No two chart photographs give exactly the same results. Additionally, I will provide the ‘peak’ resolution measurement around the frame center and edges, which could be in either the sagittal or meridional direction. For this lens, the sagittal direction is much stronger than the meridional direction.

Please bear all of these facts in mind when you review my lens resolution results. Other web sites use a different chart size, lighting, distance, camera, etc. in their resolution analysis. No two copies of a lens will yield the same results, either. Life is complicated…

Nikkor Z 28-400mm f/4-8 VR on a Nikon Z8 camera

Note that this lens is a “double-telescoping” zoom design. It doesn’t have any ‘wiggle’ to it unless you torque on it with a fair amount of force. This design keeps the lens amazingly compact at the 28mm zoom setting.

Minimum zoom setting with the bayonet lens hood attached

Target chart: edges are sagittal or meridional orientation

The MTFMapper program that I use performs resolution measurements at every single edge of every trapezoid in the chart shown above. This provides ample data for the entire field of view. The resolution mathematics doesn’t like 0, 45, or 90 degree edge orientation, which is why the chart trapezoids are oriented as they are.

Resolution Measurement Plots

28mm f/4.0 and f/5.6 MTF50

The peak 28mm f/4 center MTF50 reading is 73.3 lp/mm, while its peak edge reading is 65.4 lp/mm. This is equivalent to a center 3504 l/ph and edge 3126 l/ph resolution on the Nikon  Z9.

The peak 28mm f/5.6 center reading is 71.0 lp/mm (3394 l/ph), and the peak edge is 65.2 lp/mm (3117 l/ph).

28mm f/8.0 and f/11 MTF50

The peak 28mm f/8 center MTF50 reading is 62.7 lp/mm, while its peak edge reading is 63.2 lp/mm. This is equivalent to a center 2997 l/ph and edge 3021 l/ph resolution on the Nikon  Z9.

The peak 28mm f/11.0 center reading is 53.5 lp/mm (2557 l/ph), and the peak edge is 52.2 lp/mm (2495 l/ph).

28mm f/16 MTF50

The peak 28mm f/16 center MTF50 reading is 41.5 lp/mm, while its peak edge reading is 40.8 lp/mm. This is equivalent to a center 1983 l/ph and edge 1950 l/ph resolution on the Nikon Z9.

35mm f/4.5 and f/5.6 MTF50

The peak 35mm f/4.5 center MTF50 reading is 69.3 lp/mm, while its peak edge reading is 43.1 lp/mm. This is equivalent to a center 3313 l/ph and edge 2060 l/ph resolution on the Nikon  Z9.

The peak 35mm f/5.6 center reading is 68.9 lp/mm (3293 l/ph), and the peak edge is 52.8 lp/mm (2524 l/ph).

35mm f/8 and f/11 MTF50

The peak 35mm f/8 center MTF50 reading is 60.7 lp/mm, while its peak edge reading is 57.3 lp/mm. This is equivalent to a center 2902 l/ph and edge 2739 l/ph resolution on the Nikon  Z9.

The peak 35mm f/11 center reading is 51.9 lp/mm (2481 l/ph), and the peak edge is 50.6 lp/mm (2419 l/ph).

35mm f/16 MTF50

The peak 35mm f/16 center MTF50 reading is 39.6 lp/mm, while its peak edge reading is 38.8 lp/mm. This is equivalent to a center 1893 l/ph and edge 1855 l/ph resolution on the Nikon Z9.

50mm f/5.6 and f/8  MTF50

The peak 50mm f/5.6 center MTF50 reading is 64.8 lp/mm, while its peak edge reading is 38.6 lp/mm. This is equivalent to a center 3097 l/ph and edge 1845 l/ph resolution on the Nikon  Z9.

The peak 50mm f/8 center reading is 62.9 lp/mm (3007 l/ph), and the peak edge is 51.0 lp/mm (2438 l/ph).

50mm f/11 and f/16 MTF50

The peak 50mm f/11 center MTF50 reading is 53.0 lp/mm, while its peak edge reading is 51.0 lp/mm. This is equivalent to a center 2533 l/ph and edge 2438 l/ph resolution on the Nikon Z9.

The peak 50mm f/16 center reading is 40.8 lp/mm (1950 l/ph), and the peak edge is 40.6 lp/mm (1941 l/ph).

70mm f/6.0 and f/8 MTF50

The peak 70mm f/6.0 center MTF50 reading is 63.5 lp/mm, while its peak edge reading is 34.8 lp/mm. This is equivalent to a center 3035 l/ph and edge 1663 l/ph resolution on the Nikon  Z8.

The peak 70mm f/8 center reading is 62.3 lp/mm (2978 l/ph), and the peak edge is 46.9 lp/mm (2242 l/ph).

70mm f/11 and f/16 MTF50

The peak 70mm f/11 center MTF50 reading is 51.7 lp/mm, while its peak edge reading is 49.9 lp/mm. This is equivalent to a center 2471 l/ph and edge 2385 l/ph resolution on the Nikon  Z8.

The peak 70mm f/16 center reading is 40.8 lp/mm (1950 l/ph), and the peak edge is 41.2 lp/mm (1969 l/ph).

105mm f/6.3 and f/8  MTF50

The peak 105mm f/6.0 center MTF50 reading is 58.8 lp/mm, while its peak edge reading is 39.1 lp/mm. This is equivalent to a center 2811 l/ph and edge 1869 l/ph resolution on the Nikon Z8.

The peak 105mm f/8 center reading is 59.8 lp/mm (2858 l/ph), and the peak edge is 52.5 lp/mm (2510 l/ph).

105mm f/11 and f/16  MTF50

The peak 105mm f/11 center MTF50 reading is 52.9 lp/mm, while its peak edge reading is 51.4 lp/mm. This is equivalent to a center 2514 l/ph and edge 2457 l/ph resolution on the Nikon Z8.

The peak 105mm f/16 center reading is 40.8 lp/mm (1950 l/ph), and the peak edge is 40.7 lp/mm (1946 l/ph).

200mm f/8 and f/11  MTF50

The peak 200mm f/8 center MTF50 reading is 52.9 lp/mm, while its peak edge reading is 46.9 lp/mm. This is equivalent to a center 2529 l/ph and edge 2242 l/ph resolution on the Nikon Z8.

The peak 200mm f/11 center reading is 50.5 lp/mm (2414 l/ph), and the peak edge is 51.2 lp/mm (2447 l/ph).

200mm f/16 MTF50

The peak 200mm f/16 center reading is 40.7 lp/mm (1946 l/ph), and the peak edge is 41.5 lp/mm (1984 l/ph).

300mm f/8 and f/11 MTF50

The peak 300mm f/8 center MTF50 reading is 52.0 lp/mm, while its peak edge reading is 46.1 lp/mm. This is equivalent to a center 2486 l/ph and edge 2204 l/ph resolution on the Nikon Z8.

The peak 300mm f/11 center reading is 47.6 lp/mm (2275 l/ph), and the peak edge is 47.2 lp/mm (2256 l/ph).

300mm f/16 MTF50

The peak 300mm f/16 center reading is 38.8 lp/mm (1855 l/ph), and the peak edge is 38.0 lp/mm (1816 l/ph).

400mm f/8 and f/11 MTF50

The peak 400mm f/8 center MTF50 reading is 53.7 lp/mm, while its peak edge reading is 47.2 lp/mm. This is equivalent to a center 2567 l/ph and edge 2256 l/ph resolution on the Nikon Z8.

The peak 400mm f/11 center reading is 48.9 lp/mm (2337 l/ph), and the peak edge is 44.2 lp/mm (2113 l/ph).

400mm f/16 MTF50

The peak 400mm f/16 center reading is 39.3 lp/mm (1879 l/ph), and the peak edge is 37.8 lp/mm (1807 l/ph).

Resolution chart with overlaid resolution measurements

MTF Contrast Plots

The plots below are probably the most familiar kind of resolution-related data, although these are made from real data instead of ‘design data’. Each of these plots were made at maximum aperture.

28mm f/4.0 contrast

35mm f/4.5 contrast

50mm f/5.6 contrast

70mm f/6.0 contrast

105mm f/6.3 contrast

200mm f/8.0 contrast

300mm f/8.0 contrast

400mm f/8.0 contrast

Summary

For a ’14.3x super zoom’, these central resolutions are very, very good. The edge resolution is a bit weak. The main reason you might want to stop down the aperture is to enhance the edge resolution.

Nikkor Z 28-400mm at 400mm f/8 (cropped)

Sharp indeed.