Update: axial chromatic aberration and filtration

Following up on yesterday’s purple fringing comments, I have posted some results with various filters, including the B+W 489 IR-cut, B+W 486 UV-IR-cut, and B+W KR-12 warming filter. Details in my Leica S2 review on this page.

I don’t have the right bandpass filters to really nail it down, but it does look like purple fringing is the result of inadequate correction of violet light in the ~400 nanometer range.

These findings should be of interest to anyone wondering about purple fringing on Leica, Canon, Nikon or any other brand.