exclude files from backup with rsync -b

[Thomas Gutzler]

Hi,

is there a way to exclude files from being backed up when running rsync -b?
Let's assume the following file tree:
./src/f1
./src/temp/t1
./dest/src/f1
./dest/src/temp/t1
Now, I'm modifying both files f1 and t1 and run
rsync -a --relative -b --backup-dir=/backup/ src/ dest/
Both ./dest/src/f1 and ./dest/src/temp/t1 should have been updated but
I only want /backup/ to contain the old src/f1 and NOT the old
temp/t1.
How?

Tom