I have extension tube, but it works with lens with a aperture, it keeps image quality at price of darken light income,so if you put extension tube in between ur adapter and DA lens, DA lens will lose contact with adapter's aperture.so it is always in smallest aperture
so macro filter is one way to go, but I have tried macro filter before, +8 filter will give u soft image wide open, and purple fringe due to that magnification.
so try +4 macro filter, or the high quality version of +8 , DCR-250