Conclusion

The new M.Zuiko Digital ED 100-400mm F5.0-6.3 IS is clearly Olympus' answer to the catchily named Panasonic LEICA DG VARIO-ELMAR 100-400mm f/4.0-6.3 ASPH Power O.I.S. lens, and it's a very good one at that.

The older Panasonic 100-400mm lens does have a few advantages, though, notably a faster maximum aperture, lower weight, and a neat built-in hood. The newer Olympus 100-400mm lens has a focus limiter switch with three settings rather than two, and is notably cheaper at full RRP (although street prices at launch will inevitably be closer).

Crucially for some users, the new Olympus lens can accept both a 1.4x and 2x teleconverter, whereas the Panasonic 100-400mm is not compatible with any teleconverter. We didn't have the opportunity to test the effectiveness of the Olympus 100-400mm with a teleconverter, but if you're in any doubt about whether 800mm is a long enough focal length or not for your uses, only one of these lenses can be extended.

Both lenses otherwise share a lot of similarities, with the 200-800mm equivalent focal range providing testament to the advantages that the Micro Four Thirds system offers in terms of size and weight - telephoto lenses really are where it makes most sense from a size and weight perspective.

The Olympus M.Zuiko Digital ED 100-400mm F5.0-6.3 IS weighs just over 1.1kg, yet offers enough reach out of the box to satisfy the needs of most wildlife and sports photographers. And if 800mm still isn't long enough for you, then it can also be used with the optional 1.4x and 2x teleconverters, extending the focal length to a whopping 1600mm!

With fast and accurate auto-focusing for both still and moving subjects, 3-stops of built-in image stabilisation, full weather-proofing and decent close-focusing, this lens is well-suited to the life in the field, despite not even having the PRO billing that Olympus bestows on its very best optics.

This is backed up by the excellent optical performance. Detail is sharp throughout the zoom range, with both the centre and edges of the image proving to be excellent even when using the lens wide-open. Chromatic aberrations are not really an issue, distortion is automatically corrected on Olympus bodies, and bokeh is appealing thanks to the 9-bladed aperture.

A price tag of £1119 may put this lens financially out of reach for more casual users, but in our view it successfully bridges the gap between Olympus' cheaper, consumer tele-zooms and more pro-focused lenses like the M.Zuiko ED 300mm F4.0 IS PRO prime or the upcoming Zuiko Digital ED 150-400mm F4. 5 TC1. 25x IS PRO.

Bird, wildlife and sports photographers looking for a big zoom lens that doesn't have a massive price-tag will love the new Olympus 100-400mm F5.0-6.3 lens.

Ratings (out of 5)
Design	4.5
Features	4.5
Ease-of-use	4.5
Image quality	4.5
Value for money	4