thats becos most of the other fz are using 55mm... fz5 and fz30 is the least i can remember
and also most of the wide/tele lens from pana are 55mm as well
i'm a ex FZ7 user here too..it sure 52mm. oh..if u wanna to made sure of this just used a ruler to measure the diameter on the lens adaptor. or u can bring ur lens adaptor along to the cam shop and hv a try.