I know it might sound like a stupid question:o
But how do i check if my 400 5.6 is back focussing/front focussing?
Everytime i do it with the MFD at 3.5 and aperture wide open at 5.6 it seems that because its so far away and the aperture is not that wide that it gets to about 20-30mm back and front before the bokeh comes in.
It appears that the black line also does not seem to be tact sharp either.
Any help or suggestions how to make this easier? Shoot further away? If i do this it won't fill the frame but..