M.Zuiko 25mm F/1.2 Review

The ultra-bright M.Zuiko 25mm F/1.2 PRO is the first F/1.2 lens from Olympus and one of only a handful of such lenses for Micro Four-Thirds. Its 25mm focal-length makes it the second widest ultra-bright native lens for the Micro Four-Thirds mount and is equivalent to 50mm on a full-frame sensor. This is considered the normal focal-length and gives a very natural looking perspective.

With its normal focal-length and F/1.2 maximum aperture, the M.Zuiko 25mm F/1.2 PRO is quite versatile for a prime lens. It can produce very shallow depth-of-field suitable for classic portraits or environmental portraits and creative photography. Note that this is neither wide nor long, so a reasonable working distance is required depending on what is being framed, although the minimum focus distance is 30cm which gives 0.11X magnification.

Design & Build

As member of the PRO line of M.Zuiko lenses, this lens is built to a high standard. Its all-metal lens barrel has a very smooth finish. The lens feels very sturdy and has a completely internal focusing mechanism which gives it a fixed-size barrel. Its body is weatherproof and freezeproof like other Olympus PRO lenses.

While it is smaller than such bright lens for full-frame cameras, the M.Zuiko 25mm F/1.2 PRO is rather large for a Micro Four-Thirds lens, measuring 86mm in length and 70mm in diameter. It weighs 410g which makes it feel substantial without being heavy. There is a 62mm thread to attach filters at the front of the lens.

Mechanics of the 25mm F/1.2 PRO are superb. There is a single hybrid focusing ring which is 3cm wide and heavily textured. It gives a really good grip and remains easily usable while wearing gloves. The focus ring changes from fly-by-wire to mechanical by pulling it down 3mm towards the mount. In fly-by-wire mode, it smoothly rotates indefinitely without any stops. Since the control is electronic, focus does not change unless the attached camera expects it to which is possible in DMF mode after AF has locked.

With the ring in mechanical focus mode, there is more resistance to the rotation but it remains smooth. The throw of 90° makes manual focusing quick yet requires slow and fine movements to nail focus perfectly. When mechanical mode, the camera is set to MF, regardless of any focus mode selected in-camera. Then the focus-ring gets hard stops at the closest focus-distance and slightly passed infinity. A minor inconvenience of this mechanism is that 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.

Optical Performance

Optics of the Olympus M.Zuiko 25mm F/1.2 PRO are good. The optical formulation of this lens shows no measurable distortion and virtually no chromatic aberrations. There is however severe vignetting a very bright apertures. From F/1.2 to 2.2, vignetting is rather obvious and exceeds a ½ EV. Smaller apertures produce even illumination..

Zuiko 25mm F/1.2

Olympus OM-5 Mark II

Olympus OM-3

Panasonic DC-G97

M.Zuiko 25mm F/1.2 PRO Sharpness

Center sharpness of this lens starts off somewhat soft wide-open but it quickly improves while stopping down. By F/1.6 it is already very good and becomes nearly perfect at F/2.8. Extreme corners though are very soft from F/1.2 to F/4. There is still noticeable corner softness until F/5.6. At F/6.3 they become sufficiently sharp for a large print. Of course, under typical use for a very bright lens, edges are often out-of-focus to create background separation, so this might not be noticeable.

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 25mm F/1.2 PRO is a worthy lens for portrait and creative photography using a Micro Four-Thirds mirrorless camera. The critical issue is how much corner sharpness matters with the intended photographic subjects. Vignetting is obviously a serious issue too but can easily be corrected via software with virtually no impact on image-quality. Center sharpness, distortion and chromatic aberration-resistance are very good on this lens and rival much larger heavier lenses.

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