> >a) choose the focal length which is most commonly used, or.... > >b) test the lens at e.g. widest, then 25%, 50%, 75% then 100% >zoom. > >I have tried the 24-70mm as per a) above and the b) option. >With the b) option the FocusTune readings are so far apart >between focal lengths.
Were the b) readings all negative, all positive, or a mixture of negative and positive?
If they're all negative or all positive, then at least you're better off fine tuning (as opposed to not fine tuning).