Nikon 19mm f/4E ED PC-E Dual Aperture Series: Evaluating Sharpness at 12mm Shift (Mosaic, Nikon D810)
The Nikon 19mm f/4E ED PC-E is in effect a medium format rectilinear fisheye lens projecting a huge image circle. To maintain high image quality over a 35mm frame at 19mm is a challenge, but to do it over an area 4X or so larger is a major challenge indeed.
Accordingly, something has to give, and it seems that the “give” is in allowing a significant amount of field curvature, such that that the placement of focus becomes a key determinant for image quality when fully shifted, particularly when shifted the full 12mm along the long axis of the frame.
On a hunch based on what I saw in the first few shots, I explored focus placement on a planar subject, and I was handsomely rewarded with a finding that is essential reading for anyone using the Nikon 19mm f/4 PC-E. This evaluation presents two aperture series from f/4 through f/11, each with its own focus.
Includes dual series from f/4 to f/11 at image sizes up to 28 megapixels with huge crops.