Hello!


I am looking for some help understanding issues I'm having with my combo getting a proper auto-focus. I've not been very happy about the sharpness of some of the shots taken with the abovementioned and so I started to play with the microadjustment function.The confusing conclusion from the tests I've run so far is that the autofocus behaves differently depending on the distance from the object I try to focus on. With objects very close to the lens I need to set the ma to something about -10 to get the focus spot on. On the other hand when shooting objects further away ( > 10 meters) I need to set the ma to +7 to get sharpest shots.


All the tests were done on the longest end of the lens, fully opened (70mm f/4.5). Obviously with tripod, remote release, mirror lockup etc.


Can anyone shed any light on the issue? Is it a normal behaviour? Or maybe there's something wrong with the tests I'm doing? I'd expect the focus to behave differently depending on the focal length but not on the distance from the object...


I also ran a few tests using the same camera body but Canon's 70-200 f/4L lens and in this case I'm not sure about the results. Sometimes I seemed to be getting sharper shots with the ma correction, sometimes not.


I'll be greateful for any insight on this.





Best regards,





Wojtek