|
Unlike years ago when human calculation was used to make the glass, nowadays it is all computerised. So one is an exact copy of the previous one. I think it was Canon who made the proud boast that if you took one down from the shelf it would be an exact copy of another. This is why I do not understand the write up one sees of complaints of front or back focussing errors. I made up a simple checker and checked all of my lens. I did not find one faulty lens. The only fault one sees is build quality, such as stiff zooming etc.
|