lhorwinkle: Let-off at 1/16" from the strings in NOT normal.
richard black: He [Reblitz] said half a cm - 5mm, one-fifth of an inch (very close to 3/16).
keys60: 1/8" is the norm although some concert pianist go gradually a little less to the upper registers for more control. 1/16" is too little IMHO.
What are the pros and cons of 1/16", 1/8" or more letoff for grands and uprights?
In the 1993 edition Reblitz says for grands, "The hammers should let off when their striking points are 1/16" [1.5mm.] below the bottom surface of the strings", and for uprights, "The hammer should move within 1/8" (or 3 mm.) of the strings".
By comparison, Kawai say for grands "In the bass section letoff should be 2.0mm - 2.5m [1/12" - 1/10"], middle and treble 1.0mm - 1.5mm [1/24" - 1/16"]", and for uprights, "Let-Off should be 2.0 mm [1/12"] in the treble, 2.5 mm [1/10"] in the middle, 3.0 mm [1/8"] in the bass."