no. umask is different than chmod. umask is used in some kind of logical operation with your default permissions when a file is created to get the final file's permissions you see if you do an "ls -al".
i myself am not sure as the only thing i know about umask is how it sets up the permissions for my windows partitions in fstab.
on my windows partitions, setting umask = 0002 yeilds a final file/directory permission
rwx - rwx - r-x
umask = 00722 yeilds a file/directory permissions of:
--- - r-x - r-x
what am i saying. try this for the umask value for a final permissions of 750:
incase you want to read up on umask:
what i don't know is where you can specify setting the umask whether it's a system file or if you can set the umask when mounting your hard drive on boot up.