  Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in
studying machine optics. Hundreds and thousands of turns of free oscillations
are taken in just few tens of milliseconds. With beam covering all positions
and angles at every location TBT data can be used to diagnose focusing errors
almost instantly. This paper describes a new approach that observes focusing
error collectively over all available TBT data to find the optimized quadrupole
strength, one location at a time. Example will be shown and other issues will
be discussed.
