Converting a string of binary numbers to a binary datatype

I have a varchar field which holds numeric (binary) data e.g. '00101111' and I want to convert this to a binary data type with the value e.g. 0x00101111

But when I try the following SQL:

select top 5 flag2,convert(binary,flag2) flag2_as_binary from my_table

I get:

flag2 flag2_as_binary
--- -------------------
00000000 0x303030303030303000000000000000000000000000000000 000000000000
00000000 0x303030303030303000000000000000000000000000000000 000000000000
00000000 0x303030303030303000000000000000000000000000000000 000000000000
00000100 0x303030303031303000000000000000000000000000000000 000000000000
00000100 0x303030303031303000000000000000000000000000000000 000000000000

(5 row(s) affected)

I want some SQL that will return the following (with flag2_as_binary as a real binary datatype):

flag2 flag2_as_binary
--- -------------------
00000000 0x00000000
00000000 0x00000000
00000000 0x00000000
00000100 0x00000100
00000100 0x00000100

(5 row(s) affected)

Thanks.The sql binary datatype is actually displayed hexidecimal base 16 usinge characters 0-9 and A-F, not base 2.