And I was just begining to think I had photography figured out.

I understand DOF and have heard and read that f 64 or the higher f stops are not the sharpest f stops to use.
A picture certainly is worth more than all the words.

If you can notice the sharpness drop off with this system I can only imagine that it would be more significant will lessor quality systems?

This will certainly give me pause for thought when out shooting. My normal tendancy usually would be to maximize f stop for dof (unless of course I am using selective focus for affect)

Thanks for this illustration. I am sure it will prove to be useful in my photography

The traditional wisdom is that diffraction isn't an issue for the use that the lens is designed for and the apertures marked on the lens. From the calculator on the linked page:

http://www.cambridgeincolour.com/tutorials...photography.htm

24"x30" print
10" (25cm) viewing distance
4x5 inch film
f/32
50um circle of confusion
43um Airy disc

Diffraction limited: No