backing up an OSX image to an NTFS drive?
If you use Disk Utility to image an HFS filesystem into one dmg file, the resulting file is portable no matter what filesystem you store it on.



Where things get complicated is incremental backups. If you want incremental backups and a DIY solution, choose a sparse disk image and use rsync to update the band files that you store on NTFS, just like Time Machine does to Time Capsule.

If you really just want a painless backup solution, you might select a professional tool set such as (in alphabetical order):


Arq
Backblaze
Carbonite
CrashPlan
Mozy


Since I listed some of the more popular incremental backup software packages (some are hosted, some you can self host), the one that seems to fit your requirement the best is the free CrashPlan software that would be self hosted and need a computer connected to the NTFS drive to host the Mac data as a backup destination.