Are the existing standards and tables to calculate DOF correct for current equipment (considered the technology advance through out the years)? Harold M. Merklinger says "No". He says that "... one could expect to achieve about seven times the resolution usually assumed in that wisdom (current approach to calculate DOF)".
"According to the theories of geometrical optics, a lens focused at distance ‘X’ will require that, for maximum sharpness, the subject be positioned exactly at distance ‘X’. In practice, it is found that if the subject is a little closer or a little farther away, even the best scientific instrumentation will not be able to detect the difference in sharpness. So, in practice, there is a zone within which any subject will be imaged “sharply”, or with acceptable sharpness. That zone of lens-to-subject distances is the depthof-field." - That was the excerpt from Harold M. Merklinger's article called "Adjusting Depth-Of-Field". This article was posted in Shutterbug magazine through several issues (there are four parts). At his website Harold keeps this article for people to read (which I strongly recommend). Here are the links to it: Part I, Part II, Part III and Part IV. There is one more web page that compliments this article, it is called "Depth of Field Revisited", which you probably would want to read as well.

Yesterday I had problem with tethering the Canon 1D Mark II and Mac PowerBook. I've installed all the latest software and updates. And when I tried to control the caemra from the laptop, I could do almost everything (change the exposure settings, ISO and exposure correction), but I could not make to relase the shutter. It took me a couple of hours to try all imaginable choices, looking through the manuals and searching on the web. It seemed that everyone else was able to do it without problems.
My EOS Capture window looked as in the screenshot to the left. I pressed the spacebar or the shutter button in the window, but nothing happened. The only thing that changed is that small message in the status bar. It is saying "Quiet, delayed shutter". The message appears for a few seconds and then it is gone. So finally I gave up, I could not find the solution to this problem.
My last resort was the Rob Galbraith Forum on Canon 1D cameras. After a few hours I was relieved to get a hint on the problem. Actually I got the solution - This message was about one of the personal functions set to make the shutter sound quiter. So, first the shutter opens up, closes and only when you relase the shutter button the mirror goes back to its place. And after changing the personal function back everything started working as it suppose to. I am very grateful for the help I got from the guys at the forum. And for those who may encounter similar problem I post this message.