Here you go mate, use img burn, it's a free download
http://www.imgburn.com/index.php?act=downloaddisable anyDVD if you are using it. Insert your disk and select create image file from disc (you want full disc so you get all menus audio etc)
select where to store it and you're done
OR
use anyDVDHD to rip it to your hard drive , I usually do it as files as a full disc
then disable anyDVDHD and use imgburn to create an iso from those files
if your disc is 25 gig or less use imgburn to burn it to a 25 gig disc
if it's over that you can either just burn it to a 50 gig disc
OR
use BD ReBuilder to compress it down to 23 gig and burn it to a 25 gig disc
Personally as I've found some players don't like the compressed blu ray I do anything over 25 gig to a 50 gig disc with no compression.
But if you are playing on a PS3 I think compressed discs play fine, I think they might on most if not all sonys but my Panasonic doesn't like anything compressed to much, they get stuck on the menu.
50gig discs are pretty cheap to buy directly from Japan so I just grab 10 of them every 4 or 5 months.
All to back up my purchased blu ray collection.
Hope this helps.