M.Zuiko 12-40mm F/2.8 PRO Review

The first lens to brand the PRO name is the M.Zuiko 12-40mm F/2.8 PRO. It is designed to be a workhorse lens with its 12-40mm focal-range being equivalent to 24-80mm on a full-frame. This makes it extremely versatile and completely suitable for landscape, architecture, portrait and travel photography. Any professional with a Micro Four-Thirds system is going to need this lens.

The 12-40mm F/2.8 features a constant maximum aperture throughout its 3.2X optical zoom range. At 383g, its sturdy body has a confidence-inspiring weight without being too heavy. The lens barrel is made of metal, as is the mount, and is completely weatherproof. It is a mid-size lens with an extending inner barrel. It becomes roughly 40% longer when zoomed fully in. Since the extending inner barrel is plastic, it always stays balanced. There is a 62mm thread to attach filters at the front of the lens.

The mechanics of the Olympus M.Zuiko 12-40mm F/2.8 PRO are simply superb. There is zoom ring about 1" wide close to the lens mount. It rotates with a constant moderate amount of effort and shows no zoom creep at all. The throw is about 60° which makes framing easy. Immediately next to the zoom ring, there is slightly less wide hybrid focus ring that changes from fly-by-wire to mechanical by pulling it down 3mm towards the mount. In fly-by-wire mode, it rotates indefinitely without any stops. Since the control is electronic, focus does not change unless the attached camera expects it to. This is possible in traditional MF mode or in Direct MF mode after AF has locked. A camera setting can also change the direction of rotation for manual focusing.

When the focus ring is in mechanical possible, the lens behaves quite differently. First, it forces MF, regardless of which mode the camera is. Second, the focus direction is fixed by the lens. Then, in one neat feat of engineering, the focus-ring gets hard stops at the closest focus-distance and slightly passed infinity. The through is roughly 90° here, making precise focus easier. It has the same oddity as the 7-14mm when mounted to an Olympus OM-D E-M10 Mark II
Olympus OM-D E-M10 Mark II: The focus distance resets when the ring changes from fly-by-wire to mechanical.

There is a programmable button at the base of the lens to provide an additional customizable control. Its function depends on the attached camera. There is no way to configure the lens itself.

The Olympus M.Zuiko 12-40mm F/2.8 PRO delivers an optical performance close to perfection. Besides a very slight softening of corners at F/2.8 and F/3.5, details are extremely sharp edge-to-edge at any focal-length starting at F/4. Plus, corner softness at the widest apertures is so minimal that it would not show on anything but the largest prints.

This lens exhibits no noticeable distortion at any combination of aperture and focal-length. There is a slight vignetting noticeable in RAW files at apertures wider than F/5.6 regardless of focal-length. Corner shading becomes noticeable in JPEG images only around 12mm since the camera does a really good job correcting it. Chromatic aberrations are also nicely compensated for and rarely appear except at mid focal-lengths.

Zuiko 12-40mm F/2.8

Panasonic GH7

Olympus OM-1 Mark II

Panasonic G9 II

What is shown below are 5 crops taken from a photograph, repeatedly captured for each combination of focal-length and aperture. The smaller pieces are cropped from the extreme corners of the image, while the middle wide crop comes from the center of the image. Select an aperture in a row for a desired focal-length to see the crops from the corresponding image. When judging quality, keep in mind that these crops come from a 16 MP image which is normally used to print an image up to 20x16". On a computer display, these may appear much larger which magnifies image defects.

M.Zuiko 12-40mm F/2.8 PRO Sharpness

Upper Left

Upper Right

Center

Lower Left

Lower Right

The Olympus M.Zuiko 12-40mm F/2.8 PRO is an excellent lens with superb optical performance. It covers ultra-wide to normal focal-lengths with a moderately bright constant maximum aperture, making it the most versatile Micro Four-Thirds lens. Build quality is impeccable and its weatherproof construction will be much appreciate by professionals who must keep shooting even in adverse conditions.