Olympus 12-40 mm f/2.8  

Olympus 12-40 mm f/2.8 on OM-D E-M5, at 12 mm
Olympus 12-40 mm f/2.8 on OM-D E-M5, at 40 mm
Olympus 12-40 mm f/2.8 with lens shade
Olympus 12-40 mm f/2.8 (left) and "disposable" Panasonic 14-42 mm f/3.5-5.6 (right)
Olympus 12-40 (left) and Nikon AF-S 16-85 f/3.5-5.6 G (right)

The Olympus M.Zuiko 12-40 mm f/2.8 is Olympus' first pro-quality zoom lens for the Micro 4/3 format. It is also the first Olympus lens in the M.Zuiko Pro series. The "M." stands for Micro 4/3 and Zuiko is the traditional name of Olympus camera lenses (like Nikon's Nikkor and Minolta's Rokkor). Like most Japanese makers of camera equipment, Olympus has a considerable previous experience in professional-quality camera lenses (including several 4/3 lenses, as well as numerous professional models in the Zuiko lenses for OM film SLRs) and optical equipment for industrial and research applications (especially microscopes and endoscopes). Several quantitative tests of this lens model have been published. Basically, it has been found that this lens has a very good resolution and contrast at all apertures in its lower to mid-range of focal lengths, while it is somewhat weaker fully open at 40 mm. Even at its weakest combination of focal length and aperture, however, this lens easily beats any consumer-level zooms. The optical scheme contains a complex combination of multiple aspheric surfaces and multiple exotic types of glass. Externally, this lens has finely sculptured metal focus and zoom rings, and a shiny light-gray fascia near the front of the barrel carrying a blue strip. This is shared with other pro- and semi-pro Olympus Micro 4/3lenses, and is similar to the fascia carried by several Olympus 4/3 lenses (including consumer-level models).

This may be the first pro-quality Olympus Micro 4/3 lens that includes a dedicated lens shade (LH-66). This lens shade has two unlocking buttons, clicks in place very easily, and is unlikely to accidentally fall off. It can be mounted in reverse position on the lens for storage in a bag. Some of the Olympus Micro 4/3 lenses in the Premium series (e.g., 25 mm f/1.8) come with a lens shade, but not others, including the 12 mm f/2, 60 mm f/2.8 macro and 75 mm f/1.8. These lenses require the additional purchase of an expensive Olympus lens shade, or of a cheap Chinese knock-off from eBay.

The Olympus 12-40 is accompanied also by front and rear caps and a quite large soft bag, usable to prevent scratches against other equipment but insufficient to protect the lens from impacts. The standard front cap has center pich buttons and can be taken off and put on while the lens shade is mounted on the lens. The cap looks just as scratch-vulnerable as the lens barrel, and it may be a good idea to replace it with an all-plastic third-party cap for daily use.

This lens is splash-proof according to Olympus. I am not going to intentionally test this claim, and neither should you, because the statement "this lens is splash-proof" is usually accompanied by the fine-print statement "warranty does not cover water damage". Because of its numerous rubber seals and O-rings, it should also be relatively dust-proof, at least against sand grains - certainly not fine dust or color powders, which will get into any lens regardless of dust-or splash-proofing. It is also supposedly cold-proof, a claim that I am more likely to be testing one of the next winters (I live in Sweden). It does not have internal image stabilization, so this is one less thing that might go wrong.

This lens has a programmable button that can be pressed with the left thumb while cradling the lens and camera. Its function can be set through the camera menu system, and the range of available functions therefore depends on the camera model. By default, the button temporarily disables autofocus for as long as it is kept pressed.

The turning direction of the zoom ring in the Olympus 12-40 is the same as in other Olympus zooms. With the camera pointing to the subject, turn the zoom ring counterclockwise to increase the focal length. Panasonic zooms must instead be turned in the opposite direction, so if you mix Olympus and Panasonic zooms you may get confused.

Like in several pro-class Olympus Micro 4/3 prime lenses, it is possible to switch between autofocus and manual focus by pushing or pulling the focus ring. In manual focus mode, this displays a focusing scale. There is no DoF scale. The lens focus returns to the last used manual focus distance when switching from autofocus to manual focus. Manual focusing is by wire, but with hard stops at the ends of the focusing range. Focusing is internal, i.e. it does not change the barrel length. Zooming is mechanical and does significantly extend the barrel length. Gone for good is the aperture ring, now found only on completely manual Micro 4/3 lenses like the Samyang models.

An interesting difference from all my other Olympus and Panasonic Micro 4/3 lenses is that the aperture of the Olympus 12-40 automatically closes down to its highest f/value when the camera is switched off or the lens is removed from the camera body. Perhaps this is a response to concerns that Micro 4/3 cameras could be forgotten for an extended time with the lens pointing to the sun, which might conceivably damage the camera sensor because the shutter is always open when the camera is idle or off (I don't know if instances of this type of damage are actually documented, but the possibility exists).

Olympus 12-40 f/2.8 vs. Panasonic 12-35 f/2.8

The only direct competitor at this time is the Panasonic 12-35 mm f/2.8 X-series zoom. Also this lens, which is an earlier design than the Olympus 12-40 mm, is a good performer, and there is no clear reason to prefer either lens in terms of image quality and resolution in real-world use. The Panasonic lens is slightly smaller and lighter and has built-in image stabilization, which can be important if you use an older Panasonic body. The Olympus 12-40 is usually cheaper than the Panasonic 12-35 (by up to 10%). Are the differences between these two lens models significant? Decide for yourself:

  Olympus 12-40 Panasonic 12-35
Weight 382 g 305 g
Length (min) 84 mm 74 mm
Length (max) 112 mm 100 mm
Barrel diameter (max) 70 mm 67.6 mm
Filter mount 62 mm
58 mm
Max subject magnification 0.3x 0.17x
Min field of view (close focus) 80 x 60 mm 141 x 106 mm

As seen in the above summary, there is a size and weight difference between the two lenses, but rather modest, and nothing I would be able to notice while holding the camera or carrying a typical kit in a backpack (5-6 kg). I would say the size and weight differences in this case simply do not matter, considering that the Olympus lens gives me a slightly larger zoom ratio and significantly better close-up capabilities. The latter is for me the single most important difference between the two lenses. This allows me to take close-up pictures of good quality without having to swap out my all-round zoom for a dedicated macro lens, and without messing with add-on lenses. The focusing range of the Olympus 12-40 is continuous from infinity to 20 cm. There is no dedicated "macro" mode.

The two lenses display somewhat different combinations of chromatic aberration, vignetting and geometric distortion, but the latest Olympus and Panasonic bodies automatically correct these types of aberration (among Olympus bodies, the E-M1 corrects lateral chromatic aberration, but the E-M5 doesn't). These types of aberration can be corrected in post-processing if older bodies are used. Most professional raw converters do this automatically for all known combinations of lens and camera models. PTLens is a simple to use and cheap, but very capable, program to correct geometric distortion, vignetting and lateral chromatic aberration in a large list of known lenses, including the Olympus 12-40. One of the advantages of PTLens is that it comes with a permanent license valid for all future versions, so you should never need to purchase upgrades in the future. Manual correction of these aberrations in PTLens is also possible. Another advantage of PTLens is that, if your lens is unknown to the program, you can follow the instructions on the program's web site and provide test images to the author of PTLens for inclusion of the lens profile in the library of known lens types.

Both lenses are 2-4 times more expensive than consumer-class Micro 4/3 zooms, but significantly less expensive (and also significantly less bulky and heavy) than 24-70 mm f/2.8 full-frame or APS-C zooms of similar performance from Nikon and Canon. In this sense, Micro 4/3 keeps its promise of smaller, lighter and cheaper lenses than DSLR formats, although these gains are less extreme than in consumer-class lenses (see the above picture comparison with a typical, much slower but larger and heavier Nikon kit zoom). However, neither of these two zoom lenses is suitable for inconspicuous street photography. You will need a physically much smaller lens for this, like the Olympus 12 mm f/2 or a pancake zoom.

The barrel of the Olympus 12-40 appears to be externally mostly metal, including the focus and zoom rings. Like in the Panasonic 12-35 mm, however, the load-bearing structure of the barrel is almost exclusively made of plastic. There is nothing intrinsically wrong with plastic barrels and plastic attachments for the lens bayonet (see, e.g., LensRentals). I have been using lenses of this type for decades, and had no problem with them caused by the plastic material. Metal may have a more reassuring feel for beginner photographers, but gets uncomfortable to the touch when it is really cold, and quickly adds to the weight of a lens.

The barrel of the Olympus 12-40 is fully retracted at the 15 mm zoom setting (not at its minimum focal length of 12 mm, which extends the front barrel by about 4 mm). About 1 mm of inward travel of the extending lens barrel still seems possible at minimum retraction, judging from the distance between barrel sections. This suggests that it is not a good idea to pack this lens tightly in a bag where pressure is applied to the front and rear of the lens. Since the maximum retraction is not at one end of the zoom range but somewhere in mid-range, there is no "hard stop" with the forward and rear sleeves of the barrel solidly resting against each other. Therefore, excessive pressure applied to the front and rear ends of the lens is transmitted to the internal cams of the zoom mechanism (which have no way to further retract the lens barrel) and may dent or deform them.

There are reports of a few Olympus 12-40 specimens (probably less than half a dozen reports by users on bulletin boards) breaking at the lens mount after being dropped while mounted on a camera, banged against something, or when the camera backpack was dropped. The four plastic studs that accept the screws attaching the rear bayonet to the lens body snapped off in these cases. This lens seems to be popular, so the frequency of this type of accident may be very small. So far, Olympus has accepted to repair this type of breakage under warranty (with the exception of specimens showing clear external signs of impact, which of course is not covered by warranty - you need an extra insurance to cover this type of damage). Olympus has not acknowledged this to be a design or manufacturing fault, and replaces the broken part with a new but identical one. There are speculations that this fault may be more likely to occur in some specimens because of accidentally overtightened screws at the factory, but no confirmation.

It is never a pleasure to lose a lens, but I would rather have a lens break at its mount than the bayonet of the camera body snap off. While a broken plastic mount on a lens is easy to repair (Olympus replaces the broken barrel piece) and afterwards the lens is like new, lenses with metal barrels typically do not snap at the lens mount, but their internal mechanisms deform, their optical elements shift or shatter, and the camera body is often damaged as well. These problems are far more serious, and often too bothersome to repair.

General comments

It is of course a good thing that professional-class lenses are being introduced in the Micro 4/3 format. They seem to be very well-received by customers. Even though Olympus and Panasonic initially may not have intended Micro 4/3 as an alternative to DSLRs, and are still somewhat cautious today, the market is clearly pushing Micro 4/3 in this direction. Large corporations are, as usual, slow in realizing that the needs of the customers are more important than corporate strategies. This is why Nikon missed out on the mirrorless market by refusing to develop a mirrorless system that could be appealing to professional photographers and advanced amateurs, for fears that it could hurt its DSLR sales. The mirrorless camera market today might look very different if Nikon had developed a system equivalent to Micro 4/3 and capable of using autofocus Nikkor lenses designed for APS-C and full-frame sensors. Now it is too late. The Nikon 1 system, in spite of a few interesting features, is no match for Micro 4/3 and destined to become a footnote in the history of camera industry. Its image quality lags behind Micro 4/3 and other mirrorless formats, and the range of native Nikon 1 lenses limiting and clearly targeted to amateurs. Nikon DSLR lenses are usable only as a telephoto on the Nikon 1 cameras, because of the very small sensors.

Canon and Samsung mirrorless cameras are technically more similar to Micro 4/3 than Nikon 1, but lack lenses as well as the traction of the already established Micro 4/3 platform. Sony seems to be simultaneously trying several different strategies in the mirrorless market (some of them technically interesting, but lacking traction as well), hoping that one will emerge as a popular platform. However, the market is hardly asking for an alternative to Micro 4/3 at this point. Visit any large camera store and you will see that the Micro 4/3 section is bigger than all other mirrorless systems combined. Non-Micro 4/3 companies seem to have missed the fact that the traditional strategy of locking competitors out of one's camera system by making it proprietary is unwise when the main competitors have by far the largest, non-proprietary camera and lens system on the market. Uninformed buyers may still fall for a "minority" camera system without knowing it, but advanced amateur and professional photographers who require a broad choice of camera capabilities and lens models already know better.

I miss the rubber-clad focus and zoom rings of my Nikon and Sigma APS-C lenses, which are way more comfortable to operate than the finely machined metal of later Micro 4/3 lenses (including the Olympus 12-40) and much less vulnerable to wear and scratches. Compared to the sandpaper feel of machined metal of the newer Olympus and Panasonic lenses, or the completely smooth feel of current Sigma Micro 4/3 lenses, which can't even tell me whether I am holding the focus ring or a fixed part of the barrel, I much prefer rubber, or even the molded plastic rings of first-generation Micro 4/3 lenses. Something has gone very wrong in lens design departments. The external appearance of current lenses for mirrorless cameras seems to be designed with some sort of abstract "stylish design" in mind, or to impress inexperienced photographers, rather than for ergonomics and usability. I would welcome third-party rubber covers for the metal focus and zoom rings of these lenses, as long as they can be designed so that they don't slip or come off during use.

To lens designers who seem to prefer snazzy new external appearances over the usability of traditional lens designs, I have one thing to say: If it ain't broken, don't fix it. Design money is better spent on good image quality and a much broader range of focal lengths and lens speeds than currently available. In the end, a real photographer would not mind at all if a lens that produces good images looks like something from a Leica, Nikon or Olympus history book. Besides, Olympus is heavily investing in "retro" designs for its camera bodies, customers love them, and other brands like Sony are jumping on the bandwagon. Why not do the same with lenses? After all both the SLR Olympus OM lenses and the more recent Olympus 4/3 lenses had perfectly good rubber-clad focus and zoom rings.

My reasons for upgrading to the Olympus 12-40

The Olympus 12-40 replaces the "disposable" Panasonic 14-42 mm f/3.5-5.6 as my all-around zoom. It is hardly surprising that this leads to an improvement in image quality and lens speed. It may be more surprising to hear that it took me about two years to take this step, in part because I have good-quality prime lenses for demanding applications, in part because the development of pro-quality Micro 4/3 zooms has been very slow, but also because the Panasonic 14-42 is not such a bad lens after all. It provides a surprisingly acceptable image quality, in spite of being - and feeling like - a cheap consumer product with an all-plastic barrel (including the bayonet itself). As my Micro 4/3 kit is gradually picking up weight, I am eventually going to miss this feather-light (161 g) 14-42 Panasonic zoom. An additional reason why I am upgrading to the Olympus 12-40 is that I prefer to be prepared before the weak Panasonic plastic bayonet of the 14-42 breaks off or its plastic zoom mechanism starts to wear out (it feels moderately "gritty" since I used it in desert heat and dust).


The Olympus 12-40 mm f/2.8 is the first pro-quality Micro 4/3 zoom lens from Olympus, and one of the only two currently available zooms in this category and focal range. It is slightly larger and heavier than the Panasonic 12-35 mm f/2.8, but offers a slightly higher range of focal lengths and significantly better close-up capabilities. Image quality and versatility of use of both lenses are definitely better than with consumer-quality zooms, and as a whole these two pro-quality zooms are equivalent in these respects. The choice of one or the other of the two lenses depends on other factors, mainly on whether your camera has built-in image stabilization or requires the lens to provide it, and whether close-up photography with this lens is important for you.

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