"ACS" stands for Auto Calibration Select, a Hirox original function that
automatically selects calibration values when the magnification is changed.
This function reliably prevents erroneous selection of calibration values during image measurement, and frees the user from mistakes typically made in advanced observation and operation. This function is avaliable for all MX(G) Hirox lenses, and is standard on the KH-7700, but optional on the KH-1300.