To the Nikon Lens experts:
What is the smallest usable aperture on this lens before diffraction comes considerably into play? This is for macro photography.
A widely available formula using a circle of confusion (cc) of 1/40mm and at the maximum magnification (m) of 1:1.32
f = 1500 x cc / (m +1) equals about 16.
And the same formula will yield an aperture of 9 for the magnification at 70mm focal lenght (which is 1:3.2)
Is that your experience ?
Thanks (going to Lembeh soon...)