Purple fringing in Z 24-120mm f/4

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ZapperVT Senior Member • Posts: 2,059
Purple fringing in Z 24-120mm f/4

I was taking some back yard test shots with my new Z 24-120mm f/4 today. I noticed strong purple fringing in the corners at 24mm, f/4, as shown below. All 4 corners show a similar amount of fringing.

This surprised me because many reviews of this lens (Digitalcameraworld, ephotozine, Cameralabs, Thom Hogan, etc) say that the CA is very low at all focal lengths. But it's not low in these shots. Shots at 35mm show a much smaller amount of CA, and I observed very little CA at longer focal lengths.

The mandatory CA corrections are applied in the raw conversions of NX Studio and LRC. In NX Studio I could fix the fringing by applying the (very slow to render) "Axial Color Aberration", while in LRC 6 pixels on the purple defringe slider took out the purple. So possibly this is longitudinal CA, not lateral CA.

I compared the 24-120 to my 24-200, 24-70 f/4, and 16-50 DX. The 24-200 was worst, requiring 8 pixels of manual defringe in LRC. The 24-120 was next, requiring 6 pixels of defringe. The 24-70 and the 16-50 were the best, requiring 4 and 3 pixels respectively (equivalent numbers considering the form factor difference). So the results are consistent with my other Z lenses, with the results degrading with increasing zoom ratio.

Do other owners of this lens observe similar levels of CA in the corners at 24mm f/4? Is my lens a poor performer, or is this what I should expect?

The conditions: manual exposure, matrix meter, focus point on the center of the 2x4 nailed to the tree in the foreground, daylight WB, standard picture profile. Converted to jpg with NX Studio defaults.

Purple fringing in corners. Z 24-120mm @ 24mm, f/4

100% crop of top right corner

 ZapperVT's gear list:ZapperVT's gear list
Nikon D500 Nikon Z7 Nikon Z50 Canon EOS R7 Nikon AF-S Nikkor 50mm F1.8G +14 more
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