M.Zuiko 12-100mm F/4 IS PRO Review

The M.Zuiko 12-100mm F/4 IS PRO is a completely unique offering on the market with no equivalents by any brand for any systems. It is the highest powered Constant Aperture Zoom lens, providing an impressive 8X optical zoom while keeping an F/4 maximum aperture throughout its focal-range. Starting at 12mm, this lens offers an ultra-wide 24mm-equivalent focal-length on a full-frame, and reaches 100mm which is equivalent to 200mm. Other systems need two lenses to cover this range, usually a 24-70mm plus 70-200mm on Full-Frame and 16-50mm and 50-135mm on APS-C cameras.

Given its focal-range and aperture, the versatility of the M.Zuiko 12-100mm F/4 IS PRO is unparalleled. It is completely suitable for landscape, architecture, portrait, street and particularly travel photography. One can save bulk, weight and time spend switching between lenses by replace two of the standard professional trinity lenses with this one. This is one of the few optically stabilized lenses from Olympus, given that all their mirrorless cameras offer built-in image-stabilization. When combined with the state-of-the-art stabilization system in the Olympus OM-D E-M1 Mark II
Olympus OM-D E-M1 Mark II, the two are effective to 6.5 stops which Olympus says is only limited because of the rotation of the Earth!

Build & Design

Olympus clearly built the M.Zuiko 12-100mm F/4 IS PRO to a high standard. The lens barrel is made of metal with a nice smooth finish. It weighs 561g which is not heavy but feels dense. This lens is completely weathersealed and freezeproof. At 78 in diameter and 117mm in length, this is one of the larger Micro Four-Thirds lenses which is understandable considering its reach for a constant-aperture zoom. When fully zoomed-in, an inner barrel extends by about 5cm.

The mechanics of this lens are simply superb. There is a zoom ring about 3cm wide around the middle of the lens barrel. It rotates smoothly with more resistance than usual which prevents it from exhibiting any zoom-creep. The throw is exactly 90° which makes framing easy. The zoom ring is heavily ridged, providing a really good grip and making the lens usable while wearing gloves.

Towards the front of the lens, there is a 25mm wide hybrid focus-ring which has its front half covered in ridges for a good grip. The hybrid ring 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. In mechanical mode, it very smoothly controls the focus-distance with a 90° throw. Focusing is completely internal.

The front of the M.Zuiko 12-100mm F/4 IS PRO is threaded for 72mm filters. A bayonet mount attaches the included self-locking petal-type lens hood. Given the hood moves along with the lens, it is mostly effective when the lens is near its wide-end. On the fixed portion of the barrel these is a switch to toggle image-stabilization. It is either all on or all off, there is no way to just use stabilization in-camera since sliding the IS button to Off turns stabilization off in the camera as well. Next to the stabilization switch there is a programmable button to provide an additional customizable control. Its function depends on the attached camera. There is no way to configure the lens itself and this button does absolutely nothing when attached on a camera that cannot configure its behavior.

Optical Performance

The Olympus M.Zuiko 12-100mm F/4 IS PRO performs exceptionally well. There is a very slight amount of barrel distortion visible from 12 to 15mm and it disappears completely after that. Chromatic aberrations occur along edges of high-contrast.

Vignetting is noticeable at 12mm throughout the aperture range yet never exceeds 0.5 EV which makes it unintrusive with most photographic subjects. It improves stopped down but remains visible near wide-angle. Near the middle of the focal-range, there is no vignetting at all. It reappears towards telephoto but much less pronounced than near wide-angle. Stopping down there greatly improves things.

Zuiko 12-100mm F/4

M.Zuiko 12-100mm F/4 IS PRO Sharpness

The sharpness of this is good yet not impeccable like the 12-40mm F/2.8 PRO. At bright apertures near wide-angle, there is some slight softness at the center and moderate softness near extreme corners. The entire image gets sharper while stopping down up until the diffraction limit around F/10 but never becomes tack sharp.

Around the middle of the zoom range, center sharpness is excellent even wide-open. Corners start of soft and improve considerably stopped down to F/5.6, getting even better at F/8, once again until the diffraction limit hits. Still, edges are never completely sharp.

At telephoto, the performance is very similar to the middle of the zoom. The center there is much sharper though. There is still a high amount of corner softness wide-open which improves significantly by F/8. This does not leave much room until the diffraction limit hits, just 2/3 EV later at F/10..

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.

Upper Left

Upper Right

Center

Lower Left

Lower Right

Summary

The Olympus M.Zuiko 12-100mm F/4 IS PRO is an achievement in itself. Its unprecedented zoom range and constant aperture combination makes in incredibly versatile. Upon testing this comes at a noticeable compromise in optical performance, particularly sharpness, yet is not so pronounced as to incapacitate the lens. For common print sizes, the 12-100mm only needs to be stopped down one stop to produce highly usable results. Critical sharpness it does not have yet this lens makes up for it nicely with flexibility.