What is It?
The 12-100mm f/4 PRO lens was a bit of a surprise when it was announced. Not a surprise in that Olympus would offer a superzoom, but rather that it was tagged with the Pro designation, which Olympus reserves for its best optical designs.
From a practical standpoint, what we have here is a stay-on-the-camera lens. That's because it covers 24mm to 200mm (equivalent). That's a fairly wide angle at the short end, and a pretty sufficient telephoto reach at the long end. Indeed, the focal range is larger than the original Tamron superzoom that kicked off the whole one-lens craze.
Inside we've got a lot of special glass. 12 of the 17 elements are special formulation, with four aspherical and eight low dispersion or high refractive elements in the pipeline. Without getting into the details, the optical engineers spent a lot of time trying to correct the aberrations that come into play when trying to make a lens that covers so much range.
The lens also features Nano coating to help control reflections.
While Olympus makes a great deal about the "compact, lightweight" package of the 12-100mm f/4, the lens isn't exactly super compact or super light. It's a full 4.6" (116.5mm) in length when collapsed, and weighs in at over a pound at 19.8 ounces. Fully extended to the 100mm mark, the lens grows another two inches. Considering everything the lens does, yes, it is somewhat smaller and lighter than you might expect.
The compact and lightweight, therefore is relative. Mounted on the front of my E-M1 Mark II, the camera/lens combination is decidedly in the DSLR-neck-straining weight category, though providing 12 to 84 degree angle of view (diagonal), which is a pretty large range.
The 12-100mm f/4 features the push/pull clutch style to engage or disengage autofocus. When pulled back towards the camera, the focus ring reveals distance markings, though very minimal ones (2, 4, 10 in feet, 0.45, 1 and 2 in meters). From minimum focus (6", or 0.15m) to infinity is about a quarter turn of the ring.
The zoom ring is marked at 12, 18, 25, 35, 50, 70, and 100mm's, and also goes from minimum to maximum in about a quarter turn of the ring.
Up front we have a 72mm filter ring and a short, included, pedal bayonet lens hood (LH-76B) that can reverse mount on the lens for travel. Inside we have a 7-blade aperture diaphragm, which seems a bit under-specified considering the rest of the lens design. Smallest aperture is f/22, but I can't imagine any m4/3 user going that far down into diffraction land.
Since this is a Pro designated lens, there's more in the feature set. First and foremost is a dust and splash-proof sealing and a robust metal build quality. The lens also has an L-Fn button that can be programmed on most Olympus cameras.
Most interesting in the additions, though, is the addition of in-lens IS (and an on/off button on the lens to control it). On the E-M1 Mark II, Olympus claims that the sensor-based and lens-based IS combination with this lens provides as much as 6.5 stops of stabilization performance (CIPA standard), pretty much the highest claim I've seen anywhere to date.
The lens is made in China, and comes with a small lens case.
Source of review lens: B&H loaner.
How's it Handle?
On the smaller m4/3 bodies—e.g. the E-M10 or GM models—this lens creates a front-heavy combination that's a little out of character. On the bigger m4/3 bodies—e.g. the E-M1 Mark II or GH5—the 12-100mm f/4 is a near perfect match and provides a very nice body/lens balance.
I have a bit of a love/hate relationship with the manual focus clutch style this lens uses. I love the ability to just pull back into manual focus, and the manual focus ring on this lens is very smooth when I do that. It reminds me of the great old film lenses Olympus made when manual focusing. But I did note that the clutch got accidentally disengaged a lot when I was putting the camera into or pulling the camera from the bag. Too often I'd hit the back button for autofocus and nothing would happen. Yep, clutch disengaged again.
The funny thing is that the clutch requires some real effort to move and makes a snap noise when you do, yet somehow I often found the clutch in the wrong position without me noticing how it got there. Can't say it's a real drawback, and it may be the rough handling that my gear goes through on my travels, but it's something to be aware of.
The L-Fn button is in perfect position if you use the classic under lens form with your left hand. You'll find your left thumb finds the button easily, something that isn't always the case with lens function buttons. Well done, Olympus.
The zoom ring is on the stiff side, but smooth, exactly the way I like it. There's no zoom creep when you point the lens down. It's also easy to distinguish the zoom ring from the focus ring, even though the two are close together. The bayonet lens hood snaps in better than most I've used, but requires a button press to release.
Overall, the 12-100mm f/4 handles pretty much the way I'd want it to. At least on the bigger m4/3 bodies.
How's it Perform?
IS: In the month I've used the lens, I've had a difficult time finding a situation where the "extra" IS in the lens really comes fully into play. I will say that the combination of the camera (E-M1 Mark II) and lens IS performs quite well. So well that it becomes sort of an invisible crutch that saves your handholding butt every once in a while. I'm not a fan of using IS at high shutter speeds, as the motorized movements of IS systems can take away a bit of edge acuity at 1/1000+, but I didn't really find that to be an issue with the E-M1 Mark II and 12-100mm f/4 combo, even at 1/1000 shutter speeds.
Moreover, a week of my testing was done while navigating on a small boat in Alaska. Boats are what you call "active platforms," in that they contribute vibrations and movement that you can't control by hand holding techniques. The 12-100mm f/4 had no issues with that, even when I was pressing it to very tough situations, such as sailing by near objects while shooting at 100mm.
Focus: The 12-100mm uses Olympus' MSC focus mechanism, which they claim is high-speed, high-precision. On the E-M1 Mark II I can vouch for the focus performance: if the camera was able to find contrast on a subject focus was snappy and silent. Surprisingly so, actually. Shooting whales at twilight I was happy to see that not only could the camera see the dark subject on dark background, but that the focus performance stayed remarkably fast and tracked well, too.
The lens at 12mm (24mm equivalent) at f/4.
Crop from left side of the above image. You may be able to see that there's some loss of detail as you move from the right edge of this crop towards the left edge. Note that focus was not at this distance, though, but closer.
The lens at 100mm (200mm equivalent) at f/4.
Here the central area is exceedingly good, revealing very small details with high edge acuity. Note that this is with IS active from a moving and active platform, too.
Sharpness: The all-in-one-lens thing plays against the results a bit here. Optically, the center is excellent at 12mm wide open and drifts down to very good at f/8 (diffraction starts to come into play). The lens is better at the center at 12mm than 100mm, though the drift downward in quality at smaller apertures mitigates a bit as you zoom in. Still, from a central area standpoint, I really want to shoot with this lens at f/4 or f/5.6. Do that and you'll stay in or very near the excellent zone.
The edges and corners are, as you can probably guess, are weaker. They're strongest in the mid-range of the lens (marked 25-50mm), and what I'd call very good. Almost excellent. Curiously, the lens seems weakest in the corners at 100mm wide open at f/4, followed by 12mm at f/8 (the lens is a bit better at 12mm than 100mm at the larger apertures).
In no case would I regard the corner performance as poor, and probably not even use the term fair (unless you're way out at f/11 where diffraction takes a big toll). For the focal length range this lens has, it's performing above expectations in the corners wide open.
Overall, other than vignetting (see below), it pays to use this lens at f/4, where I'd judge it to be pretty darned good other than the extreme edges at the extreme focal lengths. With very few exceptions, this lens performs better at larger apertures than smaller. Keep it in the f/4 and f/5.6 aperture range and I think you'll be pleased with its optical performance.
Abberations: Lateral chromatic aberration is minimal and ignorable at all but 100mm, where it starts to be visible. Longitudinal chromatic aberration is minimal.
Linear Distortion: All is not perfect with this lens, and this is one of those places where you'll discover that. In true raw data (a number of raw converters apply Olympus' lens corrections automatically, including Adobe's) you'll find about 7% barrel distortion at 12mm, and 2% pincushion distortion at 100mm. Somewhere around 23mm the lens is near linearly correct. Below that expect barrel distortion, above that pin cushion. The good news is that this seems to be pretty straightforward distortion, with no mustache or wave effects in it.
The lens corrections aren't perfect, either. I see about 2% barrel distortion at 12mm even after correction, though pretty much every other marked focal length generates negligible (<0.5%) linearity distortions.
Vignetting: Again, in-camera and raw conversion corrections tell a different story from reality. Reality says that at 12mm the lens has nearly two stops of vignetting at the edges, and this doesn't get reduced significantly at any aperture I'd use on the lens. At 100mm, the raw vignetting is between two-thirds and one stop, which is much more normal.
So exactly how much do the lens corrections change things? 12mm comes down to about two thirds of a stop wide open and at f/5.6, while everything else is basically ignorable (100mm is about a half stop at f/4, less than a third of a stop above that). Here's the thing: by pulling in those corners so much at 12mm with the lens corrections, you're risking noise in the corners for anything under mid-tone values. Be aware of that, especially if you're shooting at higher ISO values. I found a number of images where my corners go noisy when shooting in low light.
Bokeh: A fair amount of onion skin and non-circular aperture artifacts, but no coloration issues I can see. I'd avoid smaller apertures with specular highlights, but other than that I found the foreground and background blurs more than acceptable.
Final Words
Some of you may be wondering how the 12-100mm f/4 compares to the 12-40mm f/2.8 I've previously reviewed. It's about as you'd expect: at the same apertures the faster lens is sharper, especially into the corners, and doesn't tend to drop off as much as you stop down (at least until diffraction takes its toll). In terms of other attributes, the faster lens has more chromatic aberration, and even slightly more true raw linear distortion (though curiously it's corrected better with the in-camera adjustments, particularly at 12mm).
Likewise, the Panasonic 12-35mm f/2.8 definitely outperforms the 12-100mm at the center, though not really at the edges except at 35mm. I haven't tested the new Panasonic 12-60mm f/2.8-4 yet, so can't speak to that versus the Olympus 12-100mm f/4.
I mention those other lenses because they basically define state of the art for mid-range zooms on m4/3 at the moment. The 12-100mm f/4 isn't far off that mark, but it's off the mark, for sure. But that's probably what you'd expect, as the 12-100mm f/4 is definitely trying to be more of a convenience, do-everything-decently lens. From the performance aspects, Olympus got this about right. The problem is that you pay more for it. If you're going for pure performance starting at 12mm in a zoom, get the 12-40mm f/2.8, as it's cheaper and definitely is a notch better in many aspects. If you're going for minimal size and weight starting at 12mm, then the Panasonic 12-35mm f/2.8 is probably your choice, and it, too, is less expensive.
Looking at the other end (100mm), both the Panasonic 35-100mm f/2.8 and the Olympus 40-150mm f/2.8 go beyond what the 12-100mm f/4 can do at 100mm, though not as much as you'd think. The Olympus 40-150mm f/2.8, though, is almost extraordinarily excellent at 100mm and f/4, as it holds the corners extremely well while basically defining center performance for m4/3. The 12-100mm f/4 just can't quite match that.
So the only real way to look at the 12-100mm f/4 is that it's one lens that doesn't fall down significantly in performance where you'd usually carry two lenses that perform better. Convenience. You pay about half price for one lens than you do for two, you lose f/2.8, and you make small sacrifices in performance here and there, but nothing that would take you down to the kit lens level of performance. You do get one gain: the 12-100mm f/4 focuses quite close. Not quite into true macro range—about 1:3 at the wide end and 1:5 at the long end—but enough so that you might not need to carry a macro lens. Again, convenience.
As such, the 12-100mm f/4 is a very tempting lens to leave on the camera most of the time. During my week in Alaska the only time I took it off was when I needed more reach for distant subjects. I could see someone using this lens as their one zoom, and perhaps supplementing it with my favorite three primes (12mm, 45mm, 75mm, all Olympus) for those times when they really need top level performance and faster apertures.
I liked this lens more than I thought I would. Olympus seems to have picked all the right compromises for an all-in-one lens. It's respectably sharp and versatile at the same time. The close focus performance is a bonus, and most of the compromises that might affect your images really get corrected by the lens corrections, in camera or in raw converters.
In the end I agonized a bit about returning the loaner lens I reviewed. I didn't keep it, but that's mostly because I already have a solid set of m4/3 lenses I use. Had I been coming into m4/3 for the first time, the 12-100mm f/4 is a mighty tempting lens to start with.
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