Olympus M.Zuiko Digital ED 12-50mm f3.5-6.3 EZ Lens
The M.Zuiko Digital ED 12-50mm f3.5-6.3 EZ lens is one of several options bundled with the new OM-D E-M5 digital camera. The first of its type with a motorised zoom mechanism, this lens covers the equivalent of 24-100mm in 35mm format, making it a useful general-purpose lens. It also features the Olympus MSC (Movie & Still Compatible) high-speed autofocus lens drive mechanism.
The M.Zuiko Digital ED 12-50mm f3.5-6.3 EZ lens. (Source: Olympus.)
The optical construction comprises 10 elements in 9 groups and includes proprietary Dual Super Aspherical lens technology. The zoom mechanism is contained within the lens barrel and floating element design enables internal lens elements to be positioned to optimise zoom and focus performance across the zoom range. Multi-coatings subdue internal reflections.
The diagram above shows the optical components and structure of the lens, highlighting the positions of the exotic elements. (Source: Olympus.)
The motorised zoom mechanism is similar to those used on video cameras. To zoom in, you simply twist the zoom ring to the left, while twisting the opposite way zooms out. The rate of zoom is controlled by the speed of the twist, providing some degree of control and fluidity. A linear motor drive provides support for autofocusing when shooting video.
Build and Ergonomics
The lens barrel is fully sealed against dust and moisture, which makes it an excellent partner for the E-M5, on which it was tested. Its build quality is excellent, with no slackness and a durable metal mounting plate.
The lens extends 83 mm in front of the camera body. Its front element is recessed a little to allow for a 52mm filter thread and attachment for the clip-on lens cap and LH-55B lens hood (which is sold separately). It doesn’t rotate during focusing, allowing angle-critical attachments to be used without requiring adjustment.
Behind the it is a stainless-steel ring carrying the name plate plus a thin navy blue band that characterises M-Zuiko lenses. Immediately to its rear is a 10 mm wide focusing ring with a narrow ribbed grip. The focusing ring rotates through 360 degrees when the camera is in AF mode.
Behind the focusing ring the barrel steps in for approximately 26 mm. In this section is a multi-position zoom ring, which is linked to a new electromagnetic zoom mechanism. The ring can be set in three positions.
Pulled back towards the camera body selects the M-ZOOM mode, which allows the zoom ring to be used like a mechanically-coupled zoom. In this mode, the ring can be rotated through about 160 degrees.
Pushing the ring forward engages the E-ZOOM mode, which works like the zoom control on a video camera, enabling users to control the speed of the zoom with the force applied while twisting the ring. A slight twist makes the lens zoom slowly, while a strong twist applies a faster change of focal length. In both cases, zooming is very smooth and steady.
The third mode, MACRO, is only accessible by pushing the zoom ring as far forward as it will go. To access this mode, you must press the MACRO button on the left hand side of the lens barrel roughly 10mm out from the mounting plate. (You can do this with your left thumb, while using the index or middle finger of your right hand to push the ring forward.)
There are no focal length markings on the lens barrel but changes can be monitored on the LCD or EVF (although the font size in the display is pretty small). A plastic covered window on the right hand side of the barrel opposite the macro button displays the mode you have selected.
Above the macro button on the left side of the barrel is a second button labelled ‘L-Fn’, which is programmable. The default setting temporarily suspends continuous AF when something interrupts the field of view while you’re shooting. It’s useful while recording movies and burst shots of action.
The lens connects to the camera with a solid stainless steel mounting plate that has 11 electronic contacts. It is offered in black and silver, to co-ordinate with the E-M5 bodies and is supplied with front and end caps.
On the E-M5, the review lens produced a good set of results in our Imatest tests, which proved it capable of matching the performance of the camera’s sensor. The highest resolution figures were recorded between f/5.6 and f/8, with the 35mm focal length delivering the best results, as shown in the graph below.
Some edge softening was detected, particularly in the middle of the focal length range, although centre resolution was relatively high. Resolution tailed off from f/9, dropping sharply between f/11 and f/22 as a result of the increasing influence of diffraction. We would not recommend using this lens at these aperture settings.
Lateral chromatic aberration was mainly within the ‘low’ band, with some straying into ‘moderate’ levels at the longest and shortest focal lengths when small apertures were used. Coloured fringing was barely detected in shots taken at 50mm and undetectable at shorter focal lengths. In the graph below, the red line marks the boundary between ‘negligible’ and ‘low’ CA, while the green line separates ‘low’ and ‘moderate’ CA.
Vignetting was well controlled and only just visible at the widest aperture settings across the focal length range. Stopping down only one f-stop made it disappear. Distortion was also very low for the lens’s focal length range, with only slight barrel distortion visible at 24mm and nothing significant thereafter. Both these defects would be easily correctable with image editing software so neither should pose problems for the majority of photographers.
Despite the lack of a lens hood, the review lens handled backlit subjects very well, even with wide angles of view. Even when the lens was pointed towards a bright light source, image contrast remained relatively high and there was surprisingly little evidence of flare artefacts.
Bokeh was smoother and more attractive than we expected for the maximum aperture range of the lens and the size of the camera’s sensor.
Buy this lens if:
- You want a capable general-purpose lens and it’s offered with the E-M5 body.
- You want superior resolution across a wide range of aperture settings with all focal lengths.
Don’t buy this lens if:
- You need true macro capabilities.
- You require a fast lens for low light work and/or differential focusing.
Picture angle: 84-24 degrees
Minimum aperture: f/22
Lens construction: 10 elements in 9 groups (Dual Super Aspherical, Aspherical x2, HR and ED Lenses
Lens mounts: Micro Four Thirds System
Diaphragm Blades: 5 (circular diaphragm)
Focus drive: High Speed Imager AF (MSC Linear Motor Drive)
Minimum focus: 35 cm
Maximum magnification: 0.36x
Filter size: 52 mm
Dimensions (Diameter x L): 57 x 83 mm
Weight: 211 grams
RRP: AU$499; US$499.99
Distributor: Olympus Imaging Australia; 1300 659 678, www.olympus.com.au
Based on JPEG files taken with the Olympus OM-D E-M5 body.
Vignetting at 12mm.
Vignetting at 50mm.
Rectilinear distortion at 12mm.
Rectilinear distortion at 50mm.
12mm focal length; ISO 200, 1/320 second at f/7.1.
50mm focal length; ISO 200, 1/250 second at f/10.
Strong backlighting; 12mm focal length; ISO 200, 1/500 second at f/9.
Macro mode; 50mm focal length; ISO 800, 1/13 second at f/6.3.
50mm focal length; ISO 1600, 1/20 second at f/6.3.
Additional image samples can be found with the review of the Olympus OM-D E-M5.
- Build: 9.0
- Handling: 8.5
- Image quality: 9.0
- Versatility: 9.0