One of the biggest problems of HM100 series is attaching (particularly rotating circular polarized) filters to the front of the lens. However one of the fixes is to attach a 72 mm filter on outside of the sunshade. This filter of course will need a snap-on cover, but it solves the issue of using polarized filter with this camera.

Also advice spreading a tiny bit of Vaseline on the threads. It makes taking on and off a breeze.