Last August, Sony announced not one, but two constant f/4 standard zoom lenses for their APS-C mirrorless cameras: The Carl Zeiss 16-70mm f/4 OSS (Reviewed Here) and Sony’s first G lens for the E-Mount: The PZ 18-105mm f/4 G OSS, which I’ll take a close look at today. The 18-105mm f/4 covers a nearly 6x…