Well I bit the bullet and bought a 2x teleconverter to extend the reach of my lenses. I have yet to find the "sweet spot" for the aperture but here's a few shots I have taken in my hunt to find the perfect focus with the new toy.

The 2x definitely shows some potential. The eye-ring in #2 and #3 reveals good detail and sharpness. The focus is off slightly in #1 and #4 so it only appears soft.

Keep at it! Thanks for sharing these.