The 12~40/2.8 m.Zuiko: (Tested on the E-M1 with firmware v 1.1.)
For the last six years, I've used the Olympus E3 and it's matching 12~60mm f2.8-4 Zuiko Zoom lens. I found it perfect for documenting visiting dignitaries (I do a fair bit of that) and general photography. At an equivalent focal length of 24 to 120mm it covered the most useful focal lengths.
It was a good lens ... but not quite a great one. (I say "was", as I've now sold it.) It suffered slight, but noticeable, barrel distortion at the wide end, though it was good from about 20mm and up. Sharpness was never an issue. It was great!
After all, Olympus, while never really giving out performance figures, claimed their "high-grade" lenses for the E system
would match or outperform a 20 mega-pixel sensor on a 4/3rs sensor. And the E3 was just 10mp (advanced for its day,
though not now!).
But, recently I switched from my E3 to the new, Olympus E-M1 and ordered the 12~40/2.8 constant aperture zoom to
go with it. It was smaller, lighter, and the reviews said "even better" than the 12~60 Zuiko. It arrived not quite a week
ago. So let's take a look.
Fit and Finish:
if you've used the 12~60 Zuiko, you'll know that the zoom ring was not the smoothest. This was not a result of poor manufacturing, but of the seals used to make the lens splash-proof/dust-proof. The 12~40 m.Zuiko is much, much
smoother, in this regard. A result, I think, of 6 more years of development in seal technology - better materials and all that. Still, it's not the silky smooth feel you get with a Leica zoom, but it is very smooth and really pleasant to use.
The manual focus ring is almost as silky smooth as a Leica - because it is a "fly by wire" system. Very smooth, with no obvious backlash - though still not as light and smooth as the focus ring on the 75/1.8 m.Zuiko prime. But then again,
the 75mm is not weather sealed... and the seals always impart some resistance ... it's either that, or they would not
seal the lens!
Curiously, the lens is at it's most compact when set to around 15-16mm. When you move the zoom ring to 12mm, the
front element moves forward, once again! This has no bearing on the price of tea in China... just a curiosity.
The lens hood is included - a nice touch. But, more importantly, it has two small release buttons, on either side of the flower-shaped hood. These release the locks that hold the hood onto the bayonet at the front of the lens. This is more important than you might think!
So, back to the release buttons on the new, LH-66 hood. Simply put, by retracting the plastic latch, when you install
or remove the hood, the "bump" on the 12~40/2.8 will not get so worn and the whole system will last many years
longer; without obvious wear or the need for repair. Nice to see Olympus paying attention to the small details.
The focus ring moves back towards the photographer, to reveal a distance scale. Do that, and the lens in in manual
focus mode. Move the ring forward and you've got AF once again. If I have any complaint with this lens, it' is that
the focus ring can be readily moved from AF to MF, if brushed against the dividers in a camera bag. I'd like to see
Olympus make the detent that holds it in one spot or the other, a bit stiffer. But, it's a minor gripe.
On the side of the lens, there is an additional Function Button (Marked L-Fn) whch can be programed to almost any function. However, I've yet to find a practical use for it! Your mileage may vary.
Something many people are not aware of, is that most "zoom" lenses are not really Zoom lenses! Most so-called "zoom"
lenses are actually variable focal length (varifocal) lenses, not true zoom (parfocal) lenses.
You can tell, by looking at the aperture. If it is varies, say f4 to f6.3 as you move through the focal lengths, it is actually
a variable focal length lens. The difference from a zoom lens, is that a variable focal length (VFL) lens does not hold
focus as you change the "zoom" ratio. True zoom lenses can be focused at any point and they will hold their focus
throughout their range. Such lenses can be easily spotted, as they have one, constant, maximum apterture, throughout
their range, such as f4, 3.5 or 2.8. There are even a few faster, true zooms, though as you approach f2 it gets much more difficult (read: expensive) to hold the quality over the zoom range.
Variable focal length lenses are simpler to design, cheaper to build and, in the age of Auto-Focus, functionally the same.
For as fast as the focus shifts, the Auto-focus system corrects for it!
The nice bit about true zooms, such as the 12~40/2.8 PRO, is that they tend to be both sharper and better corrected -
with fewer optical vices. The bad bit is that they cost more. You get what you pay for!
ONE CAVEAT: That being said, the 12~40/2.8 PRO suffers from significant complex or "moustache" distortion at focal lengths of 18m or wider. The problem is not noticeable if you shoot Jpegs, as the camera corrects for it during conversion to jpeg. If you shoot RAW files, and develop them in Olympus Viewer 3 or any of several other commercial raw developers that make such corrections automagically, then you still won't see it. But if you shoot raw files and, like me, develop them one of the less common, but very good raw developers, such as Silkypix, or one of the open-source developers, such as Raw Therapee, that do not do such corrections automatically, it can be a serious problem. Fortunately, there are two inexpensive and very effective solutions. The first is PT Lens, which does the job, very effectively, while the other is to use RAW Therapee 5, a free, open source developer that is able to correct these distortions with a single click. [UPDATE: The latest version, 5.4, now does the correction automatically, in the same way that Lightroom, Photoshop and others do it. Invisibly!]
After you've read this review, I suggest you also read my updated review of the 12~40/2.8 PRO's Moustache distortion problem (with examples), found here.
Otherwise, the lens is sharp, crisp, with high accutance. It is a convenient lens to use, in terms of size, weight, and range of focal lengths. Because of its compact size and bright, f2.8 aperture, it gets a lot of use and it delivers pro-grade results. (It must, for I have now sold thousands of images made with it and the clients are all very happy.)