What is the meaning of optimal zone on my La Specialista?

This machine is engineered to provide precise brewing pressure based on the selected coffee bean type and grind fineness. During brewing, it is essential to ensure that the indicator level consistently remains within the optimal zone.

If the indicator level drops below the optimal zone, it signifies an under-extracted espresso, necessitating the use of a finer grind.

Conversely, if the indicator level surpasses the optimal zone, it indicates an over-extracted espresso, requiring a coarser grind.

It's important to note that different coffee bean types may yield varying optimal zone readings. Keep in mind that as long as the indicator level resides within that zone, you are achieving the perfect extraction.