Acceptable Back Focal Range On Canon Lens

[vinwin]

What is the standard for back focus distance in mm which is consider as acceptable to Canon?

When the out of focus distance out of that range, Canon will need to service the lens.

 

[Robbo73]

The rule of thumb I heard that Canon consider acceptable is when the sharpest point is within the calculated depth of field. Long story short, it depends... here's a calculator which you can use along with a test paper to check "acceptability". No substitute for checking in real world situations though...

http://www.dofmaster.com/dofjs.html

http://www.focustestchart.com/chart.html

http://photo.net/learn/focustest/