Wow! I have really been needing this article. I have been learning about focusing just by experience and by experimentation. I have noticed a DOF connection with my focusing. This article really explains what has been happening to me in words I can understand. Thank you for sharing this link!
I knew the aperture stuff but i had never really considered the effect of distance to subject affecting the DOF before but it makes sense, thanks for posting a very informative article :)
http://www.stumbleupon.com/su/2uV1Hh/www.exposureguide.com/focusing-basics.htm
enjoy.