The PT-DZ870 has a maximum resolution of WUXGA (1920x1200). That's over two times the resolution of the most frequently found projector native resolution of WXGA (1280x800).
A WUXGA (1920x1200) projector native resolution is actually the best resolution across all data projectors of this type and age.
Across comparable types of projector the worst resolution is SVGA (800x600).
What does "projector native resolution" mean?