Going to Duxford tomorrow & decided to micro adjust my 100-300 f4 + x1.4 extender ready for action
First prob I notice is that the 7D only shows the already microadjusted 100-300 when the extender is added, is this right can I only have one adjustment per lens regardless of extenders or not?
Secondly I've noticed that with the above combo on it will only auto focus about 50% of the time & when it doesn't find focus it seems to lockup & won't find focus on anything at any distance unless I move the focus ring myself slightly then its fine again until it doesn't find focus & the above startss again?
I have had the extender a few years so wondering if its chip (if it has one?) isn't quite right with the 7D as the combo is f5.6 so should still autofocus?
Have to say without the extender the 100-300 works beautifully & focuses everytime, was just hoping to use the 420mm
Is it a call to Sigma or something else?