Capturing video from tape, file size question

Hi, I used a Canopus ADVC-100 to convert 8mm and miniDV old family video tapes to digital via firewire using the capture feature in Adobe Premiere Pro.  I exported them as H.264 high bit rate.  These files are very large, from which I ended up having some 300gb of old family videos, captured from tape. 

I was wondering if anyone had any suggestions about compressing these to a more reasonable size without losing quality.  I know i already compressed them by selecting H.264 (as an avi file was even larger, but with no noticable difference in quality that i could discern).  But i cant imagine why they would need to be this large still.  

Are there any plugins that can discern the appropriate compression based on the converter i used? It was just this little canopus converter.