Poor quality capture of analogue video source in Premiere Pro CC 2017

Hello everyone I am trying to ingest analogue video using Premiere Pro but the quality of the resulting captured video is worse than the source material. I am using a MacPro (late 2013) and Premiere Pro CC 2017, capturing analogue video from a BetaSP machine, using a Sony HVR-M15AE DV deck as the interface connected to the MacPro with a Firewire to Thunderbolt adapter.  By comparison, I have also tried using Blackmagic's Intensity Shuttle connected directly via Thunderbolt using its Media Express software set up to capture uncompressed video. Using both set ups, the resulting capture is soft with evidence of artefacts in the nosier parts of the picture. This link gives you some idea of the problem, with additional info. https://www.evernote.com/l/AE55ffAv51BFO4iYvlf_AsyXvBnESIBlqFo My question is: using Premiere Pro CC 2017 and my MacPro, how can I set up my workflow to ingest better quality uncompressed/lossless video than I'm currently getting with the resulting DV encoded capture? Many thanks in anticipation. James