Quality

Longitudinal Chromatic Aberration and focus shift

With large aperture lenses longitudinal color aberrations (loCA, a.k.a. “axial color” or “bokeh CA”) can be a problem. These show up as magenta coloration in the foreground and greenish hues in the background and are not easily corrected in post-processing. But in my tests the new Z-Nikkor showed neither discernible loCA nor focus shift.

Nikon Z 600mm f4 TC VR S longitudinal Chromatic Aberration (loCA)

Above from top to bottom: 600mm f4.0, f5.6, f8.0; 45% crops, left = foreground, right = background; click image for 100% crops

In all of my test-shots with the Nikon Z 600mm f4 TC VR S I could not detect any purple fringing around high-contrast edges in the focus plane and no green outlining around background subjects. Very good!

Sharpness and contrast

Let’s have a look at the theoretical performance of the Nikon Z 600mm f4 TC VR S and compare it to its predecessor plus the Z 400mm f2.8 TC VR S and Z 800mm f6.3 VR S:

Above: Nikon Z 600mm f4 TC VR S at 600mm f4.0 (left), 840mm f5.6 (right)

Above: Nikon AF-S 600mm f4E FL ED VR at f4.0 (left), Nikon Z 800mm f6.3 VR S at f6.3 (right)

Above: Nikon Z 400mm f2.8 TC VR S at 400mm f2.8 (left), 560mm f4.0 (right)

These MTF charts show the computed lens-performance of lenses wide open at infinity without influence of diffraction at 10 line-pairs/mm (red) and 30 lp/mm (blue). Higher values are better (more contrast) and the closer the dotted and solid lines are together the less contrast dependents on the orientation of the test-pattern (less astigmatism). The x-axis displays the distance from the optical axis (=center of the sensor) in mm. I’ll show you the real life performance at 4 mm (“center”), 13 mm (APS-C/DX-corner), and 20 mm (FF/FX-corner) on a 45MP Nikon Z7 body.

From the charts the Z 600mm f4 TC VR S shows extremely high overall contrast and resolution of fine details. It looks a bit better than its predecessor and clearly better than the Z 400mm f2.8 TC VR S with its internal TC switched on (at 560mm f4.0). Activating the built-in 1.4x teleconverter on the Z 600mm f4 TC VR S still delivers very good contrast/resolution at 840mm f5.6. But the Z 800mm f6.3 VR S even looks better – at least on paper.

Let’s see how this theoretical performance translates into real life results in the sharpness test based on Siemens-stars. Processing was done in Lightroom 12.0/CRAW 15.0 from RAW to Adobe Color profile with the built-in lens profile for CA, vignette control and distortion compensation applied. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. White-balance was adjusted to a neutral white and I did some exposure compensation to make the brightness of all crops match. So you will not see light fall-off in the corners.

The following are all 100% crops!

First up is an overview of the wide-open performance at different focal lengths – including 840mm and 1200mm shot with the Nikon Z TC-2.0x. You can jump to the detailed results at different apertures and comparisons with other lenses by clicking on the crops of the respective focal length.

Nikon Z 600mm f4 TC VR S; 100% crop from center, DX-corner, FX-corner

Above: 600mm, f4.0

Above: 840mm, f5.6

Above: 1200mm, f8.0 (with Z TC-2.0x)

Even wide open Nikon’s Z 600 TC looks extremely sharp across the full-frame sensor at 600mm with almost no softening towards the FX-corner. Switching on the internal 1.4x teleconverter softens the lens a bit. Mounting the Z TC-2.0x and switching off the built-in TC (1200mm focal length) results in a clear loss of contrast on fine details – even in the center. Using both the internal TC and the Z TC-2.0x to reach 1680mm focal length would certainly be overtaxing the lens’s abilities.

Field curvature is almost a non-issue with the lens. Even if you use the external TC it is of little relevance.

The following 100% crops for each focal length show the Nikon Z 600mm f4 TC VR S from wide open down to f8/f11 compared to other Z-Nikkors.

If you want to see all the details and comparisons read on. Or you can fast-forward to the performance at long distances.

Performance at 600mm:

Nikon Z 600mm f4 TC VR S at 600mm compared; 100% crop from center, DX-corner, FX-corner

Above: Nikon Z 600mm f4 TC VR S at 600mm, f4.0

Above: Nikon Z 400mm f2.8 TC VR S at 560mm, f4.0

Above: Nikon Z 600mm f4 TC VR S at 600mm, f5.6

Above: Nikon Z 400mm f4.5 VR S + Z TC-1.4x at 560mm, f6.3

Above: Nikon Z 600mm f4 TC VR S at 600mm, f8.0; also available at f11

No need to stop down the Nikon Z 600mm f4 TC VR S at 600mm. Even the FX-corner is already at its best at f4.0. The Z 400mm f2.8 TC VR S at 560mm, f4.0 is slightly softer in comparison.

Performance at 840mm:

Nikon Z 600mm f4 TC VR S at 840mm compared; 100% crop from center, DX-corner, FX-corner

Above: Nikon Z 600mm f4 TC VR S at 840mm, f5.6

Above: Nikon Z 400mm f2.8 TC VR S + Z TC-2.0x at 800mm, f5.6

Above: Nikon Z 800mm f6.3 VR S at 800mm, f6.3

Above: Nikon Z 600mm f4 TC VR S at 840mm, f8.0

Above: Nikon Z 600mm f4 TC VR S at 840mm, f11

At 840mm resp. 800mm focal length the Z 600mm f4 TC VR S (with internal TC switched on) is neck-and-neck with the other Z-Nikkors: In the center the Z 600 TC Z is almost indistinguishable from the Z 800 and both are slightly behind the Z 400 TC + Z TC-2.0x. Towards the corners the Z 800 takes the lead with the Z 600 TC slightly and the Z 400 TC + Z TC-2.0x more clearly behind. Stopping down to f8.0 produces a slight improvement in acuity especially in the center of the Z 600 TC.

Performance at 1200mm:

Nikon Z 600mm f4 TC VR S + Z TC-2.0x at 1200mm compared; 100% crop from center, DX-corner, FX-corner

Above: Nikon Z 600mm f4 TC VR S + Z TC-2.0x at 1200mm, f8.0

Above: Nikon Z 400mm f2.8 TC VR S + Z TC-2.0x at 1120mm, f8.0

Above: Nikon Z 800mm f6.3 VR S + Z TC-1.4x at 1120mm, f9.0

Above: Nikon Z 600mm f4 TC VR S + Z TC-2.0x at 1200mm, f11

At 1200/1120mm the Z 600mm f4 TC VR S + Z TC-2.0x takes the lead with the Z 800 + Z TC-1.4x having a slight advantage in the FF/FX-corner. The Z 400mm f2.8 TC VR S + Z TC-2.0x (and internal TC switched on) is the softest of the three. Stopping the Z 600mm f4 TC VR S + Z TC-2.0x down to f11 improves acuity. But the effect is limited as diffraction is already setting in.

All-in-all the Nikon Z 600mm f4 TC VR S lens is extremely sharp when used at 600mm focal length even wide open at f4.0. Evidence to its superior performance are the very good results when used with the built-in 1.4x TC. Even in combination with a Z TC-2.0x it delivers very usable results. Only using both teleconverters at the same time taxes the limits of this lens.

Performance at long distances

The Siemens-star test-targets are shot at a distance of 45x focal length (i.e., at around 27m for 600mm focal length). But performance of lenses also depends on the shooting distance. Therefore, I shot a building around 1 km away. Processing was done in Lightroom 12.0/CRAW 15.0 from RAW to Adobe Color profile with the built-in lens profile compensating CA, vignetting, and distortions. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no color or saturation adjustment. But I had to increase contrast by +33 to compensate for the reduced visibility at that time.

The following image shows the complete scene wide open plus 100% crops from the center, DX-corner, and almost FX-corner. You can access the large original, but the file is for personal evaluation only and cannot be used in another publication or website without permission.

Nikon Z 600mm f4 TC VR S

Above: Nikon Z 600mm f4 TC VR S at 600mm, f4.0, 1/400, 200 ISO; click image for 4k version, here for large original

The Nikon Z 600mm f4 TC VR S again shows very good resolution of fine details in this long-distance test. Unfortunately deteriorating atmospheric conditions did not let me continue testing at 840mm and 1200mm.

Vignetting and distortions

To make it easier to see light fall-off in the corners of a full-frame sensor I’ve arranged a series of three shots each with the Nikon Z 600mm f4 TC VR S both with and without the built-in teleconverter. All images were shot as JPGs on a Nikon Z7 with picture control set to Standard and developed to the same brightness in the center. They are shown with vignette control Off (1st row) resp. Normal (2nd row).

All comparisons in this chapter were shot as JPGs on a Nikon Z7.

Above: Nikon Z 600mm f4 TC VR S at 600mm

Above: Nikon Z 600mm f4 TC VR S at 840mm

Wide open vignetting is very mild with the lens profile applied and practically irrelevant once the aperture is closed one stop. With vignette control set to Normal the extreme corners are lifted about 0.4 EV when the aperture is wide open.

Distortions are almost non-existent:

Distortions: Nikon Z 600mm f4 TC VR S at 600mm, auto distortion control Off (top), On (bottom)

Rendering of point-light sources at night-shots

Night-shots pose a different challenge for lenses as the contrast is even higher than under bright sun and point-light sources can reveal some weaknesses such as coma, haloing and colour-aberrations that do not show up as prominently in other test-shots. The 100% crops below the main image show the effect of coma in the FF-corner of the Nikon Z 600mm f4 TC VR S at different apertures:

Above: Nikon Z 600mm f4 TC VR S at 600mm f4.0; click image for 4k version, here for large original

Above: Nikon Z 600mm f4 TC VR S at 600mm; 100% crops from the FX-corner at f4.0 (left), f5.6 (middle), f8.0 (right)

The Nikon Z 600mm f4 TC VR S produces very little coma even wide open. The test also shows no color artifacts around bright streetlights.

Bokeh quality

This test is for the rendering of point-light sources in an out-of-focus background. The circle of confusion that is produced by the test is pretty indicative of Bokeh performance (in the background) and light fall-off. Ideally the out-of-focus image of the point-light is evenly lit and perfectly circular, with no “onion-rings”, and without coloration. Large aperture lenses normally produce an effect known as “cat’s eye” the further away from the optical axis the point-light is projected. This is due to optical vignetting in the lens barrel when light enters the lens from an angle.

Above: Nikon Z 600mm f4 TC VR S at 600mm, f4.0; 4k versions available at f4.0, f5.6, f8.0, f11

The diameter of the Bokeh balls in the center is determined by the entrance pupil of the lens which is a huge 150mm. Compression of the circle towards the corners is relatively strong wide open. The circle of confusion in the center is no longer perfectly circular from f5.6 onwards – which is the reason you can produce diffraction spikes with this lens already at f5.6. The inside of the Bokeh balls is smoothly textured but there is a bit of outlining – albeit without coloration from loCA.

Head over to my page with sample images which were all shot wide open to get a better impression of how Bokeh of the lens looks in different situations. I personally find it smooth in the transition zone and background although double contours sometimes can be seen:

Above: Nikon Z 600mm f4 TC VR S at 600mm, f4.0, 50% crop; click here for large original

Close-up performance

The Nikon Z 600mm f4 TC VR S achieves a maximum magnification of 1:6.6 without teleconverter and 1:4.7 with teleconverter in close-up shooting. The crops shown below are at 1:4.7 from 0mm, 14mm, and 19mm off the center of the sensor respectively, the area of sharp focus is 113 x 169mm.

Nikon Z 600mm f4 TC VR S at 840mm, 1:4.7 magnification; 100% crops

Above: Nikon Z 600mm f4 TC VR S at 840mm, f5.6

Above: Nikon Z 600mm f4 TC VR S at 840mm, f8.0

Above: Nikon Z 600mm f4 TC VR S at 840mm, f11

At 840mm focal length close-up performance is pretty good – even wide open. Stop down to f8.0 to lift acuity a bit and get very satisfying results. Field curvature is very low, in this test all crops are from the same shot.

Sun-stars

The lens produces sunstars already at f5.6 – but they are nicest at f8.0. See below:

Above: Sunstars from the Nikon Z 600mm f4 TC VR S at 600mm, f5.6, f8.0, f11 (from left to right), 50% crops; click image for 100% crops

Next check out my sample images!