you can take your analogue, 8mm or Hi8mm tape - load it into a Digital 8 camera, and at least for Sony, this will provide a proper DV bitstream through the firewire to iMovie or whatever editing program you are using. alternatively, you can for example plug in a VCR with a favourite VHS to the Digital 8 camera's rca jacks. and do the same thing - the Sony Digital 8 will convert it to a DV bitstream, through firewire to into iMovie, etc.
in this case, we have both Sony *and* Apple to thank. it's one way to archive valuable footage - and it's a good thing to then store and use the "Digital/DV" copies to work on or play, instead of using the master/original tapes over and over again. you will not lose any quality, as the DV format will handily surpass anything you had as original/analogue tapes anyway. it won't make your original quality *better* but it will faithfully capture whatever was there to begin with.