Review Olympus 12-40mm f/2.8 Pro M.Zuiko Digital ED (m43)

28 November 2013

The Olympus M.ZUIKO DIGITAL ED 12-40 mm f/2.8 PRO lens is the first model from the new, professional M.ZUIKO PRO lenses series from Olympus. This spectacularly good lens, according to our review, meets in terms of construction and its image quality the high demands of professional photographers or other perfectionist photographers. No wonder this Olympus 12-40 mm f/2.8 zoom lens is also offered as a kit lens for the Olympus OM-D E-M1. This combination delivers such high quality images that as a professional, you can confidently switch to a micro-43 camera.

Olympus 12-40mm f/2.8 Pro M.Zuiko Digital ED @ Olympus OM-D E-M1
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A 12-40 mm zoom lens on a micro-43 camera is a universal zoom lens, which can be used for almost all forms of photography. The zoom range of the Olympus 12-40 mm f/2.8 in terms of field of view is equivalent to a 24-80 mm zoom on a camera with a full frame sensor. Thanks to the high, constant brightness, this lens is an alternative to a large set of commonly used lenses with a fixed focal length (converted to a camera with a full frame sensor): 24 mm, 28 mm, 35 mm, 50 mm and 85 mm.
Construction
If you compare the Olympus 12-40 mm f/2.8 with other micro-43 lenses, then this professional Olympus lens with a diameter of 82 mm is relatively wide and heavy (382 grams). Also, the filter size of 62 mm is impressive for a micro-43 lens. In comparison, the Panasonic 12-35 mm f/2.8 has a diameter of 68 mm, weighs 305 grams and has a filter size of 58 mm. A standard 14-42 mm kit lens is less bright, but much smaller and lighter. In terms of hand-fit, this zoom lens is a fine combination with our Olympus OM-D E-M1 test camera. Compared to a traditional 24-70 mm zoom for an SLR camer, the dimensions of the Olympus 12-40 mm f/2.8 are modest. The relatively light Canon 24-70 mm f/4 weighs 60% more, is 30% longer and has a 25% larger filter size. A 24-70 mm f/2.8 lens for an SLR camera is even bigger and heavier.
This lens is very well put together. You notice that immediately when you pick up this lens. On this, it meets the toughest demands of a professional. The zoom ring and focus ring are muted and yet operate smoothly. The Olympus 12-40 mm f/2.8 – just like the professional lenses for SLRs – is extra well sealed against dust and splash water. Earlier we referred to a video (Camera Review under kitchen faucet), in which this lens with an Olympus OM-D E-M1 is held under a running faucet and continues to function normally. According to the specifications, the Olympus 12-40 mm f/2.8 is also suitable for photography in freezing cold. We have not tested this, but we believe it right away. When zooming it seems, if you listen very well, as though you can hear the rubber rings. This sound may be picked up as you zoom in or zoom out when making a video.	{insertgrid ID = 289}
L-Fn
Close to the mount is an interesting little button with the label “L-Fn”. On the Olympus OM-D E-M1, we were able this link to button a function of choice, as we have seen before on Samsung cameras. This does not have to be any specific lens function, but can also be camera settings like white balance. By linking the L-Fn button to the HDR function, I had the HDR functionality with 1 press of a button. Handy!
Auto focus
The Olympus 12-40 mm f/2.8, with the Olympus OM-D E-M1, offers lightning-fast focus using contrast detection. For contrast detection the sensor signal is used, whereby you aren’t bothered from front focus or back focus. Fast focus applies not only to static subjects, but thanks to the phase-detection on the sensor of the Olympus OM-D E-M1, fast-moving subjects are also quickly and accurately brought into focus. On the right, you can see one from a series of images, shot with a speed of approximately 5 frames per second, where the AF captured image each well and focused at the right point. Click (2x) on the image for a partial magnification at 100%.
The AF of professional SLR cameras like the Nikon D4 or Canon 1Dx is still slightly faster in tracking moving subjects. Thanks to MSC technology, focusing is quiet, which is nice for video. Analagous to USM/HSM lenses, you can overrule the AF manually at any time. This option only works if you have the camera set to AF + MF in advance. A ‘Manual Focus Clutch’ mechanism makes it possible to switch at any time from AF to manual focusing. If you use the manual focus clutch, then the focus ring has a hard stop at 20 cm and at infinity. That is an advantage over lenses with a fly-by-wire focus ring, that you can continue to turn after reaching the shortest or longest focal length.
Image stabilization
Because the sharpness of pictures shot by hand depends on the photographer, this test has to always be conducted by the same photographer in order to be able to make comparisons. For each vibration reduction test, dozens of pictures are taken, of which the sharpness is determined with Imatest. The image stabilization of Olympus is among the very best image stabilization systems that currently exists. A picture taken without image stabilization at a focal length of 40 mm with a shutter speed of 1/50 sec is just as sharp as a picture taken at a shutter speed of 1/6 sec. That’s a profit of 3 stops. At slower shutter speeds the profit went up to 4 stops. A picture taken without image stabilization at a shutter speed of 1/25 sec is as sharp as a picture taken at a shutter speed of 0.67 sec.

If you assess the sharpness visually and therefore accept some loss of sharpness relative to a picture taken from a tripod, then at a focal length of 40 mm (= 80 mm 35 mm equivalent), thanks to the image stabilization, you can take another picture at a shutter speed of 0.67 seconds. When shooting at close range, the profit by image stabilization is always smaller, even then, at a focal length of 40 mm you can use a shutter speed of about 1/10 second if you use the VR. That’s very good.
Olympus 12-40 mm f/2.8 @ 32 mm, f/2.8, 1/100 sec, 200 ISO, + Olympus OM-D E-M1
Creative Tip: Professional cameras such as the Olympus OM-D E-M1 also offer a wide choice of creative filters, which you choose in the camera for a shot that looks as if Photoshop has been applied. When shooting, save in RAW and jpg files simultaneously, and then you can let your creativity loose on the jpg files by trying out different filter settings of the camera. The simultaneously saved RAW files offer the freedom to experiment more afterwards or to apply totally different creative filters.
Resolution
At aperture 4, the highest sharpness is achieved at the shortest focal lengths. Starting from a focal length of 15 mm units, we already measure the highest sharpness from full aperture. This is a somewhat academic distinction, because the sharpness is so consistently high from corner to extreme edge, from aperture 2.8 to aperture 11, that every aperture produces a perfectly sharp picture. At a smaller aperture (f/11 and above), the sharpness drops off a bit due to diffraction. We previously reviewed the Panasonic 12-35 mm f/2.8 on an Olympus OM-D E-M5. If you compare the test results of the Panasonic 12-35 mm f/2.8 with the results for the Olympus 12-40 mm on an Olympus OM-D E-M1, then you can say that the differences in sharpness between RAW and jpg or between the E-M1 and the E-M5 are possibly greater than the differences in quality between the two lenses.
Both lenses are almost as sharp in the outer corners as in the center, and both lenses deliver the highest possible sharpness starting at maximum aperture. A 20 megapixel SLR with a full frame sensor and a 24-105 mm delivers pictures that are as sharp as a 12-40 mm (or 12-35 mm) zoom on a 16 megapixel micro-43 camera. As a completely unscientific practice test, I hung two cameras around my neck and under similar conditions (24 mm f/5.6 @ full frame and 12 mm f/2.8 @ micro-43) took a picture. Click on the picture below for two partial enlargements at 100% for both standard jpg files. Differences in point of view, focal length and color are more noticeable if you compare the pictures directly with each other. In the corners, the full frame shot shows much more distortion and chromatic aberration. In order to compare MTF50 results for this lens with MTF values for lenses tested on cameras with an APS-C or full frame sensor, we set the micro-43 test camera to a 2: 3 ratio. In other words: we tested this lens with a resolution of 14 megapixels (2:3 ratio) instead of 16 megapixels (4:3 ratio). Using the native 4:3 aspect ratio will yield slightly higher MTF values.

Vignetting
When testing the Olympus OM-D E-M1, we set the camera to correct vignetting. The term that Olympus uses in the camera menu for vignetting correction is: “shadow compensation”. You choose “shadow compensation” in the adjustments menu G. This compensation does not fully eliminate all vignetting, but it does ensure that in practice you never have more than a half stop difference in brightness between the center and the corners in RAW files that you open in Lightroom or Photoshop, or jpg files that you have stored in the camera. If you open your RAW files with a different RAW converter, then you run the chance of encountering vignetting. That can be corrected with software.
Distortion
The distortion is also automatically corrected, meaning that jpg files and RAW files that you open in Lightroom or Photoshop exhibit no visible distortion over the entire zoom range. Therefore, there are no correction profiles in Photoshop or Lightroom for Olympus or Panasonic lenses: the distortion has been corrected in the camera. This is (thankfully) not something that you have to turn on or off in the camera menu. If you bypass the distortion correction of the camera, you will see that the lens design yields visible barrel-shaped distortion up to a focal length of 20 mm. Distortion above 20 mm is pincushion-shaped, which becomes visible at approximately at the maximum focal length (40 mm).
Bokeh
The quality of the background blur, the bokeh, is determined by, among other things, the depth of field. The depth of field of an f/2.8 lens on a micro-43 camera corresponds to the depth of field of a f/5.6 lens on a camera with a full frame sensor. That is an ideal depth of field for a nice full-screen portrait, which is the focus of nose to ear with a beautiful background blur. The Olympus 12-40 mm f/2.8 has 7 aperture blades, which at maximum aperture give a nice round bokeh. There is indeed an edge to the bokeh, which at apertures to f/4 is slightly more visible (move your mouse over the image). The Panasonic 12-35 mm f/2.8 shows a bokeh with a less sharp edge on the outside, but with more of an “onion peel” character (multiple rings within each other). You will probably see differences only if you take pictures under completely identical conditions, and then place the images right next to each other. With both lenses you can create pictures with a beautiful background blur, possibly just as nice as the bokeh of a good lens on a camera with an APS-C sensor, but not as beautiful as you get if you use a bright lens on a camera with a full frame sensor.
Flare
The Olympus 12-40 mm f/2.8 is very resistant to flare. It makes you almost wonder why a flower-shaped lens hood is included. Even with night shots around a bright light source directly in frame, only a very small area of flare shows. We didn’t encounter any ghosts in our test shots. Of all the lenses we’ve tested to date, for both micro-43 cameras and for SLRs, this zoom lens is among the very best.
Chromatic aberration
The Olympus OM-D E-M1 test camera, unlike the Olympus Om-D E-M5, is able to correct for chromatic aberration. This is not at all necessary in this particular case. In all situations, jpg or uncorrected files, regardless of the aperture at all focal lengths, the lateral chromatic aberration is so low that you will have in practice never be bothered by it.
Conclusion Olympus-12-40mm test
{insertgrid ID = 387}	See our list of tested lenses or our list of tested micro-43 lenses to compare the performance of this lens to other lenses.
WYSIWYG score: This table shows the performance of this lens when you save the files in the camera as jpg, including all in-camera lens corrections (distortion, chromatic aberration). This score gives you for this lens/test camera combination: “What you see is what you get”.	{insertgrid ID = 308}
Pure RAW score: This table shows the performance of this lens when the file is stored in the camera as a RAW file. This score approaches the intrinsic quality of the combination of lens and test camera. If you make use of Photoshop, Lightroom or SilkyPix for converting RAW files, then the RAW scores for chromatic aberration and distortion are the same as the jpg scores.	{insertgrid ID = 309}
Pros	Cons
Image quality and build quality of uncompromising high, “professional” level High brightness Exceptionally high sharpness starting at maximum aperture from corner to center Extra well sealed against dust and splash water. Suitable for use in the freezing cold Clutch mechanism with hard stops at 20 cm and infinite for manual focusing	Not cheap Relatively large and heavy for a micro-43 lens For video: Zoom not completely silent
I more often run into professional photographers who shoot with an Olympus OM-D E-M5 or a Panasonic GH3. That’s not for nothing. As you can read in our camera tests, the picture quality of this micro-43 camera at ISO values up to 3200 ISO gives nothing up to SLRs with a larger sensor. Pick a good lens and you can make beautiful pictures with these cameras. The Olympus 12-40 mm f/2.8 is such a good lens that shows that you can make professional-quality pictures with the micro-43 system. Our testing shows that this robust, dust- and splash-proof micro-43 zoom lens can be a high-quality alternative for a much larger and more expensive 24-70 mm f/2.8 zoom lens. The sharpness starting at f/2.8 is already very high from center to the extreme corners. The bokeh is a little less woolly, but that’s to be weighed against a great insensitivity to flare, low chromatic aberration and high sharpness in the corners at full aperture. The high purchase price should not be a barrier for so much photo enjoyment. {insertgrid ID = 600}