How to increase the bandwidth using fdesign from [20, 20000] to[20,50000] ?

Hi,

i'm designing my 1/3 octave filters using fdesign in the way that is in the help section of the function:

 f.BandsPerOctave = 3;
 f.FilterOrder = 8;
 Fs=52734;
 F0 = validfrequencies(f);
 Nfc = length(F0);
 for i=1:Nfc,
    f.F0 = F0(i);
    Hd3(i) = design(f,'butter');
 end

The problem is that the fdesign functiondoes only work from [20,20000] Hz and i want to work from [20,50000] does anyone have a clue about how to do this? All the best!