Olympus M.Zuiko Digital ED 100-400mm f/5-6.3 IS review

In case anyone has missed the news, Olympus’s imaging division faces an uncertain future, as it’s being carved out from the parent business and sold to a venture capital company. But this hasn’t stopped the release of its latest lens, the M.Zuiko Digital ED 100-400mm f/5-6.3 IS. It’s an optically stabilised ultra-telephoto zoom that joins the firm’s mid-range line-up, rather than its premium Pro series.

There’s already a highly regarded telezoom of this type in the Micro Four Thirds system, in the shape of the Panasonic Leica DG Vario-Elmar 100-400mm F4-6.3 Asph OIS. You’d probably think that Olympus has made a more portable alternative, given the lens’s slower maximum aperture, but instead the new optic somehow contrives to be significantly larger and heavier. Its £1100 launch price is a little lower than its counterpart, but only by £100. So why would you consider buying it?

It turns out that the new lens’s trump card might be its compatibility with Olympus teleconverters. Fit the MC-14 (£249) and it becomes a 140-560mm f/7.1-9, and with the MC-20 attached (£379), it’s a 200-800mm f/10-13. And while DSLR users may assume that this must come at the cost of autofocus, this isn’t the case, as mirrorless systems don’t share the same limitation. It’s all very intriguing, but does it actually make sense?

Olympus 100-400mm F5-6.3: Features

Long telezooms tend to be optically complex, and Olympus has used 21 elements in 15 groups, including four Extra-low Dispersion (ED), two High Refractive Index (HR), and two Super High Refractive Index (Super HR) glass elements to help keep optical aberrations at bay. Olympus’s ZERO coating reduces flare and ghosting, and the diaphragm employs nine rounded blades to give a near-circular aperture, in a bid to provide attractive bokeh.

While this is Olympus’s third IS lens, it differs from the firm’s existing optics in that it doesn’t support Sync IS, in which the in-lens and in-body stabilisation systems work together for maximum effect. Instead, when the lens IS is enabled, the camera’s in-body system is automatically disabled (although confusingly, it’ll still appear to be active on the camera’s Quick Control Panel). With such a long telephoto, the optical stabilisation is likely to be doing most of the work anyway, so this isn’t perhaps as much of a loss as it sounds.

UPDATE: Olympus has released firmware updates for select camera models (E-M1X, E-M1 Mark III, E-M1 Mark II and E-M5 Mark III), primarily to add support for focus bracketing with the 100-400mm. Interestingly, they also enable rolling motion around the lens axis to be corrected by the camera’s IBIS. This is good news to videographers, but probably won’t make a lot of difference for stills photography, because roll movement only contributes significantly to blur at much slower shutter speeds than are likely to be usable hand-held with this lens.

Indeed at 800mm equivalent the optical stabilisation has an awful lot of work to do counteract the effects of camera shake, and as a result is rated to 3 stops, dropping to 2 stops when a teleconverter is fitted. This might sound meagre to Olympus users accustomed to getting considerably more from their camera’s in-body IS, but it’s worth bearing in mind that with most of the subjects this lens will be used for, you’ll generally need to maintain fast shutter speeds anyway, to prevent motion blur.

As usual for a large telephoto, the 100-400mm includes a sturdy metal tripod mount. It rotates freely and can be locked in any position, with index markings (but not click-stops) at every 90°. In a particularly welcome move, an Arca Swiss-type dovetail profile means it can be clamped directly onto many tripod heads, while the collar can also be removed for hand-held shooting. However, some users may prefer the Panasonic lens’s easily removable, low-profile tripod shoe.

The lens has a minimum focus distance of just 1.3m, providing a handy 0.57x equivalent magnification and facilitating interesting close-ups of subjects that might prove skittish if you approached them with a shorter macro lens. Filter users will find a 72mm thread surrounding the front element, while a deep bowl-shaped plastic hood is supplied in the box.

Olympus 100-400mm F5-6.3: Build and handling

As befits its mid-range status, the 100-400mm employs plastic rather than metal for much of its outer barrel. But it’s still perfectly nicely made, and Olympus says that it’s built with the same standard of dust, splash and freeze-proofing as its Pro-series lenses, which have proven to be extremely robust.

Weighing in at about 1.4kg with the tripod mount and hood attached, and measuring over 20cm in length, this is one of the largest and heaviest Micro Four Thirds lenses. As a result, it feels distinctly front-heavy even on high-end Micro Four Thirds cameras.

Users of Olympus’s small E-M10 and E-M5 bodies will find themselves supporting the lens entirely with their left hand, and will benefit significantly from using an add-on grip for their camera if possible. Even E-M1-series users will likely appreciate the extra purchase afforded by a vertical grip. To me, the smaller and lighter Panasonic version matches the Micro Four Thirds philosophy better.

Thankfully, the lens still handles quite well. The zoom ring rotates smoothly through 90°, with no change in resistance at any point. This is much better than the rather ‘sticky’ zoom found on its Panasonic rival when it comes to making fine adjustments. I had no problem with zoom creep, but a switch allows locking at the 100mm position anyway, with a white inlay to show its status. The front of the lens extends by approximately 6cm when zoomed to 400mm.

On the left side of the barrel you’ll find a conventional control panel, with a set of well-spaced switches for limiting the autofocus distance range (1.3m to 6m, 6m to infinity, or full), selecting between auto and manual focus, and turning IS on or off. Unfortunately, these switches get hidden awkwardly under the tripod foot when you rotate it for shooting in portrait format. The Panasonic lens works better in this regard, as its control panel is located on its rotating collar.

Olympus 100-400mm F5-6.3: compared to Panasonic 100-400mm

Here’s a size comparison between the Olympus M.Zuiko Digital ED 100-400mm f/5-6.3 IS and the Panasonic Leica DG Vario-Elmar 100-400mm F4-6.3 Asph OIS. You can see just how much bulkier the Olympus lens is, despite its two-thirds stop slower aperture at 100mm. In its retracted position, it’s 3.4cm longer and 3.4mm larger in diameter (note this doesn’t take into account the tripod shoe).

The Olympus lens is also much heavier. On its own with no accessories it weighs 169g more (1120g vs 951g), but if you factor in the caps, hood and tripod mount, the difference in what you’ll actually be carrying around amounts to almost 300g (1405g vs 1114g).

Each lens has its own pros and cons. The Panasonic has a low-profile tripod shoe that can be easily unscrewed when the lens is mounted on the camera, a zoom lock that can be engaged at any focal length, and a control panel that rotates to stay accessible when shooting on a tripod in portrait format. It also has a shallow sliding built-in hood, with a somewhat impractical clamp-on extension. The Olympus has a smoother zoom ring, a conventional hood (which incidentally also fits the firm’s 40-150mm f/2.8 zoom), and will attach directly to many tripod heads thanks to its Arca Swiss-compatible mount.

Olympus 100-400mm F5-6.3: Autofocus

In terms of autofocus, the 100-400mm behaves much as we’d expect for a modern lens. With an internal-focus design powered by a stepper motor, AF is fast, silent and accurate, especially if you’re shooting static or slow-moving subjects. The key point to appreciate is that with such a long telephoto, depth of field is extremely limited, so it’s essential to position a fine focus point exactly where you need it, to ensure the subject is properly sharp. But even this can be challenging when working hand-held at full telephoto, as the IS can struggle to stabilise the viewfinder image sufficiently.

When it comes to keeping focus on moving objects, you’ll likely be limited by the capability of your camera, which varies widely between Micro Four Thirds bodies. Using the phase detection-equipped Olympus OM-D E-M1 Mark III, I found the lens was perfectly capable of tracking focus on large, relatively predictably-moving subjects such as trains or planes, but struggled with smaller, more erratic wildlife. Here the slow maximum aperture clearly does it no favours compared to Olympus’s 40-150mm f/2.8 and 300mm f/4 Pro-series telephotos. On the older, contrast detection-based E-M5 Mark II, I found it was only able to keep up with relatively slow-moving subjects, and the first frame in a burst was almost invariably out of focus.

Olympus 100-400mm F5-6.3: Performance

Assessing the Olympus 100-400mm for image quality can be a difficult task, because its performance is so intimately tied to the fact that long telezooms are most likely to be used outdoors to shoot moving subjects, such as wildlife, sports, or vehicles. This generally requires fast shutter speeds to combat motion blur, which coupled with the relatively small maximum aperture, means that you’ll often need to use high ISOs, even in bright sunlight.

Lock the lens down on a tripod and point it at a brick wall using a low ISO, and you’ll find it’s capable of delivering impressively sharp images wide open. As tends to be the case with telezooms, it’s slightly weaker at 400mm than at 100mm, particularly towards the corners of the frame, where it benefits from being stopped down to f/8. Like all Micro Four Thirds lenses, pixel-level sharpness visibly deteriorates if you set the aperture much smaller than this, due to the inevitable onset of diffraction.

Under controlled indoor tests I found the optical stabilisation worked pretty well, giving a good percentage of usable images at 1/25sec at 100mm, or 1/100sec at 400mm. This matches Olympus’s claimed 3 stops, and wasn’t any better or worse than its Panasonic rival. But shooting outdoors can be a different proposition, particularly on a windy day that’s buffeting your lens as well as your subject. At full zoom, I often observed the IS really struggling to stabilise the viewfinder image.

Once you start shooting real-world subjects, you’ll rapidly find that with its small aperture and demand for fast shutter speeds, this is an incredibly light-hungry lens. Even in bright sunlight, you’ll generally need to boost the ISO a couple of stops. When light levels drop lower, for example at dawn or dusk or on a cloudy day, you’ll quickly find yourself the wrong side of ISO 3200. This really isn’t Micro Four Thirds’ comfort zone, with noise and noise reduction robbing images of detail.

When everything comes together, though, the lens is capable of delivering excellent results, particularly in good light and at relatively close range, where you can fill the frame with your subject without having to crop and aren’t affected by any atmospheric distortion. So it’s great for subjects such as garden birds, or as a pseudo-macro for shooting insects.

But I was less happy with the images I got in even moderately low light, where the requirement for very high ISOs means that it’s difficult to capture much in the way of fine detail. How much this will matter to you depends on how you assess your files: if you demand sharp, noise-free results at 100% onscreen, forget about it. But if instead of pixel peeping you view the image as a whole, you might well be rather happier.

Olympus 100-400mm F5-6.3: Use with  teleconverters

Potentially one of the Olympus 100-400mm’s biggest selling points is its compatibility with the firm’s MC-14 and MC-20 teleconverters. These bring extraordinary telephoto reach, equivalent to 1100mm and 1600mm at full telephoto, respectively.

The catch lies with the very small apertures: f/7.1-9 with the MC-14, and f/10-13 with the MC-20. But this doesn’t come with the same operational limitations that you’d get with DSLRs: the viewfinder image remains bright and clear, and autofocus still works remarkably well. In general, you’ll run out of sufficient light to get a decent image long before the AF fails.

Instead, the key question is whether you can actually get any more detail using a teleconverter, compared to simply cropping and enlarging an image taken using the lens alone. The problem lies with diffraction: optical calculations suggest that theoretically, all you’re really doing is magnifying the Airy blur disc. At which point you’re just making life harder for yourself, for no clear gain.

In practice it’s possible to get quite credible results with the MC-14, as long as you keep the aperture wide open and shoot in bright sunlight. However it’s pretty much essential to use a monopod to steady the lens, and preferably a tripod. But as predicted, close examination of the images reveals little in the way of really fine detail.

Switching to the MC-20 is definitely a step too far. It does provide ludicrous reach, and at full zoom you can almost fill the frame with the moon. But the lens becomes extremely difficult to handle, and the tiny aperture means there’s precious little fine detail to be seen. As it turns out, ye cannae change the laws of physics.

Olympus 100-400mm F5-6.3: Verdict

When the 100-400mm first appeared on Olympus’s roadmap, I had high hopes that it would prove to be a worthy competitor to Panasonic’s well-liked version. But after a couple of weeks using it, and several thousand shots, I’m still not quite convinced.

Indeed in what feels like a rare misstep from Olympus, it’s somehow delivered a lens that’s considerably larger and heavier than its rival, despite having a two-thirds stop aperture disadvantage at 100mm, which narrows only gradually as you zoom in. This bulk makes it noticeably more awkward to use, so it only really handles nicely on E-M1 series bodies, despite a price that seems aimed more towards E-M5 users. It also lacks a number of useful features that you get with the Panasonic.

This doesn’t mean the lens is a non-starter, though. It’s capable of producing really attractive results, especially in bright sunlight, and its usability with the MC-14 teleconverter could well prove alluring to some buyers. Its price will presumably drop over time, too, which obviously would make it a more attractive proposition. Overall, though, it’s a strange release from a company that places such a strong emphasis on providing lightweight, highly mobile kit.