Are you trying to count the number of cells in the range that equal F, or are you testing that ANY of the cells in the range equal F?
To count the no. of cells which equal F: =COUNTIF(Z3:BZ3,"F")
To count the no. of cells which CONTAIN F: =COUNTIF(Z3:BZ3,"*F*")
To test whether ANY of the cells equal F:=COUNTIF(Z3:BZ3,"F")>0 (returns TRUE/FALSE)