|Why make things more difficult than needed.|
Just copy as many photos to a DVD as will fit and repeat as needed. Make 2 copies while you are at it.
If you insist on keeping multiple individual files as one folder then there are many programs to SPAN multiple DVDRs. If you have Nero or Roxio, read the help files as many version of those programs can span multiple disks.
Imaging programs may also be able to accomplish what you want to do.
Are you backing up other personal files too?