Closest Focusing Distance - 1.3m throughout range, including with teleconverter.Lens Construction - 28 elements in 18 groups built-in teleconverter - 7 elements in 4 groups.Focal Length - 150mm - 400mm with the built-in teleconverter - 187.5mm - 500mm.It's still a big lens, but not uncomfortably so. When I first pulled this lens out of the box I was surprised to find that it was both smaller and lighter than I expected. Plus, I would have the only one in North America (oh, the pressure!) In the end however, I'm so glad that I accepted the invite because this lens is exceptional! We were heading into wintery weather, most of the migratory birds in my area had long gone, and finding other wildlife would be a real challenge.

When Olympus offered to send me a pre-production copy I was quite hesitant. These are my first impressions based on 5 days of shooting with the lens. I'll get to why in a moment, but just a reminder that this isn't a formal review. But the m.Zuiko ED 150-400mm f/4.5 TC1.25x IS PRO (now, there's a mouthful) stands out amongst these.

I've shot with practically every lens made by Olympus for the micro 4/3s system and each one is built to very high standards. Although compensation was paid for this review, I endorse their products because I truly believe in the quality of their gear Disclosure: I am an Olympus Visionary and as such, receive compensation from Olympus America.

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