I hope that this can help clarify things... The issue is whether you have a string or a number. A couple of demo's:

#!/usr/bin/perl
use warnings;
use strict;

#prints "0" becaus 0x30 is "0" in ASCII
my $char = "\x30"; #quotes makes $char a "character"
                   # result being the number "0" in ASCII
                   # which translates to numeric 0!
print "$char\n";   #prints "0"
printf "%08b\n", $char; #still prints "0"!!

print "\nNow, 0x30 as a number, not a character\n";

#without the quotes, we have a binary number...
my $char2 = 0x30;
print "$char2\n";        #prints 48 (decimal 0x30)
printf "%08b\n", $char2; #prints "00110000"

__END__
0
00000000

Now, 0x30 as a number, not a character
48
00110000
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Sometimes the hex function can be useful.

#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

my @strings=("ab30ff","30","ab1a30");
for (@strings){
    $_=hex $_;
}

foreach my $hex (@strings)
{
   printf "%08b\n", $hex;

}

__END__
101010110011000011111111
00110000
101010110001101000110000
[download]