Olympus M.Zuiko Digital ED 12-40mm f/2.8 PRO lens
The 12-40mm f/2.8 lens is an impressive performer, delivering quality that rivals that of many DSLR+fast zoom pairings that target serious enthusiast photographers. But its great advantage is being able to do this in a more compact, lighter-weight unit.
Fast focusing and near-silent AF operation also make this lens attractive.
Announced in September 2013, concurrently with the OM-D E-M1 camera, the Olympus M.Zuiko Digital ED 12-40mm f/2.8 PRO lens introduced the company’s ‘professional’ series of Micro Four Thirds System lenses with high optical performance and dust- and splash-proof construction. Covering focal lengths equivalent to 24-80mm on a 35mm camera, this lens maintains a constant f/2.8 maximum aperture throughout the 3.3x zoom range.
The M.Zuiko Digital ED 12-40mm f/2.8 Pro lens. (Source: Olympus.)
The optical design of this lens is complex for a standard zoom, comprising 14 elements in 9 groups with one aspherical ED lens, two aspherical lenses, one DSA lens, two ED lenses, one HD lens and two HR lenses.
The diagram above shows the positions of the exotic elements in the lens design. (Source: Olympus.)
ZERO (Zuiko Extra-low Reflection Optical) coating (introduced with the 60mm f/2.8 macro lens) has been applied to the optical surfaces to minimise ghosting and flare and improve performance with backlit subjects. This lens is also sealed to prevent the entry of dust and water splashes from entering and meets the same dustproof and splashproof standards as the OM-D E-M1 as well as being freeze-resistant.
Who’s it For?
The relatively high price of this lens signals it is designed for serious photographers at both professional level and enthusiast. Physically, it’s best paired with either the flagship E-M1 Mark II or the last two generations of the E-M5, where its 84-30 degree angle-of-view coverage makes this lens useful for many types of photography, ranging from landscapes and architecture (outdoor and indoor applications) to portraiture and even close-up shooting.
Although M4/3 lenses are usable on both Olympus and Panasonic cameras, if you require stabilisation, you will need a Panasonic body with built-in O.I.S., such as the G95, GX9 or G9. You may lose some autofocusing speed with this combination, compared with the Olympus bodies.
Being dustproof, splashproof and freeze-resistant, it’s an excellent choice for outdoor photographers and its focusing and zoom rings are designed for easy use when wearing gloves. The hood is reversible for storage and has a bayonet lock with pinch clips and metal rim. The lens cap fits well and is quick to remove and replace.
A key feature of the 12-40mm f/2.8 PRO lens is its manual focus clutch mechanism, which provides easy switching between auto and manual focusing. When the focus ring is pushed forward, autofocusing is enabled. Pulling the focus ring back engages manual focusing.
Hard stops are provided at the closest focusing distance and also at infinity in manual focus mode. The resolution of the snapshot focus mechanism has been improved and a distance indicator is revealed when the focus ring is pulled back, enabling focusing to be adjusted like conventional manual focus lenses.
For autofocusing, this lens employs an inner focusing system and includes a compact, lightweight focusing unit consisting of two cemented lenses. The MSC (Movie and Still Compatible) mechanism is driven by a high- precision metal shaft and fast linear motor drive system, which eliminates the need for noisy gears and makes this lens ideal for shooting movie clips.
It also provides an easy way to pull focus when you want to swap quickly from one subject to another at a different distance. If you set the focus to a specific distance in manual mode then switch to AF and focus, the lens ‘remembers’ the MF position and allows you to swap focus instantly by simply pulling the focus ring back. The remembered distance is retained, regardless of the focal length, making it easy to shift focus quickly – or keep a subject focused – as you zoom.
Build and Ergonomics
This lens was originally designed and built to match the OM-D E-M1 and, accordingly, it is fully environmentally sealed, making it dust-, splash- and freeze-proof. The build quality is much as you would expect from its design and price point: sturdy but highly refined with a very solid metal mounting plate.
The overall finish is similar to that of Olympus’s top-quality prime lenses, which have textured controls to allow easy use with gloved fingers. In autofocusing mode, the focusing ring is located 20 mm behind the front of the lens. It’s about 20mm wide and the leading 12 mm is finely ridged to provide a secure grip. When this ring is pulled back in the switch to manual focusing mode, it reveals a narrow distance scale with settings for 0.2, 0.5 and 1 metres plus 1, 2 and 5 feet as well as an infinity position.
The zoom ring is 27 mm wide and located just behind the focusing ring. It carries a 22 mm wide band of ridged strips and its trailing edge is marked with the 12mm, 14mm, 18mm 25mm 35mm and 40mm focal length positions. This ring turns through roughly 80 degrees, extending the inner barrel by 30 mm as you zoom from 12mm to 40mm.
Both zoom and focusing rings are well damped with just enough resistance to enable precise settings to be made. The front element doesn’t move during focusing or zooming and the lens can focus down to 20cm at all focal lengths, which brings it to within about four centimetres of the subject at 40mm, where it provides a 30% magnification, extending to 5.5 cm at 12mm.
Between the zoom ring and the mounting plate is a programmable L-Fn button, which is located just under your thumb when you cradle the camera plus lens with your left hand. It’s similar to the button on the Olympus 12-50mm f/3.5-5.6 lens and can be used to hold focus because autofocusing stops when this button is pressed. And, like that button, it’s not usable on all M4/3 cameras.
When you’re shooting with the C-AF+TR focus mode while recording a movie, the Fn1 button starts the camera tracking on the subject within the selected AF area (chosen before staring movie recording). Release the L-Fn button and the camera will re-focus again.
The review lens performed very well on the OM-D E-M5 Mark III body we used for our tests. Autofocusing was very fast and completely silent in all modes, including C-AF. Tracking AF was consistently accurate, including during movie recordings, where focus changes were frequent.
Our Imatest tests showed the resolution of JPEG files came very close to meeting expectations for the review camera’s 20-megapixel sensor across all focal length settings between f/3.5 and f/6.3 and were only a little lower at wider apertures. Results from raw files were consistently above expectations for both near-centre and edge measurements across this aperture range.
Diffraction began to take effect from f/7.1 but resolution remained relatively high to f/16 with a steep drop down to f/22. Some edge softening was identified at wider aperture settings with the shorter focal lengths at our standard test distances but it was only detectable with close examination of test shots.
Softening was more noticeable in close-up shots, where it can be advantageous in situations where the viewer’s eyes need to be drawn to the centre of the field. The graph below shows the results of our Imatest tests.
Lateral chromatic aberration was negligible at all lens apertures and focal lengths, as shown in the graph of our Imatest results, below. The red line marks the boundary between ‘negligible’ and ‘low’ CA.
The combination of lens hood and ZERO coating was effective for minimising flare and increasing fine contrast, although when a very bright light source was included within the frame, some veiling flare resulted, as shown in the sample images below. Normal backlighting was handled very well.
Our assessments of rectilinear distortion were carried out on converted raw files to avoid the impacts of the in-camera corrections applied to JPEGs. While distortion has often been a weakness in M4/3 lenses, in the 12-40mm PRO lens we found it to be very well controlled. Very slight barrel distortion could be seen at 12mm but distortion was effectively negligible for the rest of the zoom range.
Vignetting was another aberration that is automatically corrected in JPEG files in the review camera so, once again we had to evaluate raw files. Slight vignetting was seen at f/2.8 across the zoom range increasing as the lens was zoomed to 40mm. Fortunately, most of it was gone by f/4 and this aberration is easily corrected in image editors and most raw file converters so we don’t see it as a significant issue.
The seven-bladed lens diaphragm appears to close to an almost perfect circle, making this lens capable of producing smooth and pleasing bokeh. But a lot depends on the focal length, shooting angle and relative brightness of the background.
The 40mm focal length can deliver close to 1/3 life size magnification at its closest focus and, with an evenly-lit background, delivered smooth and attractive bokeh at f/2.8. With shorter focal lengths, the bokeh could become a little choppy where there were bright patches in the background. Stopping down even 1/3 of an f-stop increased the chance of irregularities showing up.
Autofocusing performance, which is influenced by the algorithms in the camera, was generally excellent and the face-detection function worked flawlessly, even with quite fast-moving subjects.
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Picture angle: 84 to 30 degrees
Minimum aperture: f/22
Lens construction: 14 elements in 9 groups (including 2 aspherical, 1 aspherical ED, 1 DSA, 2 ED, 1 HD and 2 HR elements)
Lens mounts: Micro Four Thirds
Diaphragm Blades: 7 (circular aperture)
Focus drive: MSC (Movie & Still Compatible) linear motor
Stabilisation: No (relies on in-camera sensor-shift system)
Minimum focus: 20 cm
Maximum magnification: 0.3x
Filter size: 62 mm
Dimensions (Diameter x L): 69.9 x 84 mm
Weight: 382 grams
Standard Accessories: LH-66 Lens Hood , LSC-0918 Lens Case , LC-62D Lens Cap, LR-2 Rear Lens Cap , Instruction Manual, and Warranty Card
Distributor: Olympus Imaging Australia; 1300 659 678
Based on JPEG files from the Olympus OM-D E-M5 Mark III.
Vignetting at 12mm.
Vignetting at 25mm.
Vignetting at 40mm.
Rectilinear distortion at 12mm.
Rectilinear distortion at 25mm.
Rectilinear distortion at 40mm.
12mm focal length, ISO 200, 1/320 second at f/11.
40mm focal length, ISO 200, 1/160 second at f/11.
Close-up at 12mm; ISO 200, 1/1600 second at f/2.8.
Close-up at 40mm; ISO 200, 1/1600 second at f/2.8.
Smooth bokeh and good subject isolation at f/2.8; 40mm focal length, ISO 200, 1/4000 second.
27mm focal length, ISO 200, 1/500 second at f/8.
Strong backlighting; 40mm focal length, ISO 200, 1/800 second at f/11.
Veiling flare at 24mm; ISO 200, 1/100 second at f/8; JPEG file.
The same image captured as a raw file and corrected with the standard auto setting in Adobe Camera Raw.
35mm focal length, ISO 200, 1/160 second at f/11.
40mm focal length, ISO 200, 1/500 second at f/7.1.
12mm focal length, ISO 200, 1/1250 second at f/8.
40mm focal length, ISO 160, 1/8000 second.
30mm focal length, ISO 200, 1/320 second at f/5.
Face detection AF response; 28mm focal length, ISO 200, 1/640 second at f/5.
Additional image samples can be found with our review of the Olympus OM-D E-M5 Mark III.
RRP: AU$1249; US$999
- Build: 9.0
- Handling: 9.0
- Image quality: 9.0
- Versatility: 8.8