Sharpness

For this sharpness test the Micro-Nikkor 40mm f/2.8G lens was attached on a Nikon D7000 camera body, which in turn was mounted on a sturdy tripod. The self-timer was activated, and Exposure Delay Mode was enabled in otder to eliminate any vibrations resulting from mirror movement. Slight tonal changes are due to slight changes in natural light during the session. The 100% crops represent about 1/400th of the total frame area.

The full frame

The lens is sharpest at f/5.6, but when you use it for macro work you will have to stop it down way past this value in order to get an acceptable depth of field. Unfortunately, diffraction  impacts heavily on resolution and sharpness at the smallest apertures – this is something you will need to keep in mind.

(A note on f-stops: the maximum aperture of this lens is f/2.8. However, the so-called “effective f-number” varies with the reproduction ratio. At 1:1 magnification, the “effective brightness” of the lens is f/4.2.)

Aperture	Centre Crop	Edge Crop
f/2.8
f/4
f/5.6
f/8
f/11
f/16
f/22