Optional join

Hi,
 I trying to write a query that will join 2 tables.   Here's the concept:
Table 1: table1, primary key pk1
Table 2: table2, primary key pk2

One of the fields (f2) in table2 contains either the primary key of table1 or a NULL value.  So normally a pretty basic
query:

SELECT table1.*, table2.pk2 FROM table1, table2 WHERE table2.f2 = table1.pk1;

BUT what I would like to do is show all records of Table 1 even if there is no match in Table 2.  Meaning that the
reultscould be  
table1...   table2.pk2
table1...   NULL

Doable?

Thanks.