Imaging Resource posted their Olympus 150-400mm PRO in-depth Field Test. This is their conclusion:
So, how to sum-up one of Olympus’ most impressive lenses? If you’re a serious wildlife photographer and can afford it, get it.
Price aside, the Olympus 150-400mm f/4.5 IS Pro is an incredible lens for nature and wildlife photographers. The image quality is fantastic, offering tack-sharp performance across the zoom range, with or without its built-in teleconverter. AF is also spot on and very fast, and the incredible close-focusing distance provides even more versatility, allowing for nice close-up performance that’s atypical of super-telephoto lenses.
In terms of the overall build quality, the lens is, as expected, built like a tank, even if it is surprisingly light. The lens feels incredibly solid and very well built, as one would expect from a $7,500 piece of optical equipment.
In the end, yes, the Olympus 150-400mm f/4.5 IS Pro very expensive in and of itself, but it’s also very, very good. Lenses for serious wildlife photography are often quite pricey and are a serious investment, and the Olympus 150-400mm is no exception. However, when compared to several of its full-frame counterparts, the 150-400mm Pro is both reasonably priced and incredibly versatile. If you want to slim-down your wildlife gear, and free yourself from tripods and monopods, the lightweight Olympus 150-400mm Pro lens is worth serious consideration.