Filter tables

Hi all.

I have this sample setup:

CREATE table t1 ( t text, id int );
CREATE TABLE f1 ( t text );

INSERT INTO t1 VALUES
  ( 'field1',1 ),
  ( 'field2',1 ),
  ( 'field3',1 ),
  ( 'field1',2 ),
  ( 'field3',3 )
;

INSERT INTO f1 VALUES
  ( 'field1' ),
  ( 'field2' )
;

What I'd need to do is to "filter" t1 against f1 to get only the rows
( 'field1',1 ) and ( 'field2',1 ).
Of course both t1 and f1 don't have a defined number of rows, though usually
t1 should be much bigger that f1.

I have a rather complex solution in mind with loops in a plpgsql function and
am wondering whether there is one simpler.

Thanks a lot.

--
Reg me Please