Fungi Photography

All text and images © David Noble.

Diffraction Effects

Modern lenses usually perform the best around the middle of the aperture range - eg at f 5.6 or f 8. "Best" here means the sharpest image, not only in the centre but also on the edges and corners. After about f 11 diffraction effects can set in. Difraction depends on the lens aperture used and the sensor in the camera (size of the sensor and the total number of pixels)

Here are some images cropped from near the centre of the frame reproduced at 100% size. Ignore the effects of increasing depth of field as the lens is stopped down - just examine the detail in the 7 -

f 2.8

f 4

f 5.6 (the subject or the camera may have slightly moved for this photo)

f 8

f 11

f 16

f 22

f 32

Discussion

To me, it looks like the f 11 image is the sharpest for this lens (Canon 100 mm Macro L IS). However, I cannot see too much image falloff for f 16 and f 22. The image taken at f 32 is not as clear - eg look at the diagonal scratch on the lower part of the 7 - it does not stand out that well.

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