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Olympus M.Zuiko ED 12-40mm f/2.8 PRO Lens Review

Gary Wolstenholme reviews this professional weather-sealed 12-40mm f/2.8 Olympus Micro Four Thirds lens.

|  Olympus M.Zuiko ED 12-40mm f/2.8 PRO in Interchangeable Lenses
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Handling and Features

Olympus M Zuiko Digital ED 12 40mm F2 8 Pro (8)

This standard zoom lens for Micro Four Thirds (MFT) system cameras provides an angle of view equivalent to a 24-80mm lens used on a 35mm format camera and sports a constant f/2.8 maximum aperture throughout the zoom range. The lens is also dust and splash proof, and is available from around £800 at the time of writing. In this review we'll take a look at how it performs.


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Olympus M.Zuiko ED 12-40mm f/2.8 PRO Handling and Features

Olympus M Zuiko Digital ED 12 40mm F2 8 Pro (12)

The lens barrel is constructed from high quality plastics, with a glossy finish and the bayonet is metal with a rubber gasket to prevent the ingress of dust and moisture into the camera body. Despite the robust construction the lens only weighs 382g. As far as size and handling are concerned, this lens is a perfect match for the Panasonic Lumix G6 camera body used for testing.

Olympus M Zuiko Digital ED 12 40mm F2 8 Pro (5)

As focusing is performed internally the 62mm filter thread does not rotate, which makes this lens ideal for use with graduated and polarising filters. Sliding back the focus ring reveals a distance scale and automatically changes the camera to manual focus mode, which is ideal for applying quick adjustments. However, it is incredibly easy to nudge this by accident when changing lenses, so care needs to be taken to ensure the lens is in the desired mode for shooting. The minimum focus distance is 20cm throughout the zoom range, which is ideal for close ups, or shooting in claustrophobic environments.

Olympus M Zuiko Digital ED 12 40mm F2 8 Pro (10)





Olympus M.Zuiko ED 12-40mm f/2.8 PRO Performance

At 12mm sharpness is already outstanding across the frame, and there is only a slight improvement in clarity when stopped down one stop. This pattern is repeated at 18mm with excellent sharpness being achieved between maximum aperture and f/8.

Zooming to 40mm results in a slight reduction in sharpness at maximum aperture, although performance is still very good in the centre of the frame and good towards the edges of the frame at f/2.8. Stopping down to between f/4 and f/5.6 results in outstanding sharpness across the frame at this focal length.

This lens appears to be particularly affected by diffraction at small aperture settings, with a dramatic reduction in sharpness being visible at f/22. Although this may not be an issue for many, those wishing to use small apertures for longer exposures, might want to use a neutral density filter instead so that the lens can be kept closer to its optimum aperture range.





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How to read our charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column.

The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple.

For this review, the lens was tested on a Panasonic Lumix G6 using Imatest.

Chromatic aberrations are well controlled throughout most of the zoom range. Between 12mm and 18mm fringing only exceeds half a pixel width when stopped down to between f/11 and f/22. At 40mm fringing just exceeds three quarters of a pixel width towards the edges of the frame at f/2.8, but even so, this low level should be difficult to spot.





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How to read our charts

Chromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.

For this review, the lens was tested on a Panasonic Lumix G6 using Imatest.

Falloff of illumination towards the corners is fairly typical for a standard zoom lens, and shouldn't pose too many issues. At 12mm and f/2.8 the comers are 1.35 stops darker than the centre of the image and at 40mm, and falloff is reduced and the corners are only 0.76 stops darker than the image centre. Stopping down to f/5.6 results in visually uniform illumination across the frame throughout the zoom range.

Distortion is well corrected in camera, but without corrections applied, Imatest detected 5.51% barrel distortion at 12mm being replaced with only 0.965% pincushion distortion at 40mm. The level of distortion  at 12mm will be quite noticeable in images with lines parallel to the edge of the frame, although the distortion pattern is uniform across the frame throughout the zoom range, which should make applying corrections in image editing software afterwards, relatively straightforward.

A petal-shaped hood is supplied with this lens, which does a reasonable job of shading the lens from extraneous light that may cause issues with loss of contrast or flare. Even without the hood in place, this lens is very resistant to flare and contrast levels hold up well when shooting into the light.

Olympus M.Zuiko ED 12-40mm f/2.8 PRO Sample Photos




Value For Money

Currently, this lens is available for around £800, which seems pretty good value for a lens of this quality, especially when the price of Panasonic's 12-35mm f/2.8 is taken into account. Despite having a shorter zoom range it currently costs £30 more. This is probably due to it including optical stabilisation, which isn't much of a selling point if your camera body includes stabilisation itself.




Olympus M.Zuiko ED 12-40mm f/2.8 PRO Verdict

Those looking for a professional specified standard lens for their Micro Four Thirds camera are now spoilt for choice with offerings from Panasonic, and this lens from Olympus.

This lens delivers outstanding sharpness through much of the zoom range at maximum aperture and sports a robust, dust and splash proof build, all while remaining compact and lightweight. The excellent performance of this lens will certainly win it many fans, that's for sure.





  The Olympus M.Zuiko 12-40mm f/2.8 lens delivers outstanding sharpness through much of the zoom range at maximum aperture with a dust and splash proof design.



Olympus M.Zuiko 12-40mm f/2.8 PRO Pros

Outstanding sharpness from maximum aperture
Compact and lightweight
Robust build
Dust and splash proof
Quick access for manual focus
Good value



Olympus M.Zuiko 12-40mm f/2.8 PRO Cons

Manual focus control easily nudged when changing lenses
Heavily affected by diffraction at small aperture settings






Olympus M.Zuiko ED 12-40mm f/2.8 PRO Specifications

Lens Mounts
  • Panasonic Micro Four Thirds
  • Olympus Micro Four Thirds
Focal Length12mm - 40mm
Angle of View30° - 84°
Max Aperturef/2.8
Min Aperturef/22
Filter Size62mm
35mm equivalent24mm - 80mm
Internal focusingYes
Maximum magnificationNo Data
Min Focus20cm
Box Contents
Box ContentsLSC-0918 Lens Case, Lens Hood, Lens Cap (Front and rear)

View Full Product Details






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The closest focusing distance of 20cm. is evidently from the subject to the focal plane in the camera and not to the end of the lens. I discovered this when trying to measure the accuracy of the manual focusing scale. The length from the focal plane to the end of the lens hood when the lens is fully extended to 40mm zoom is 16cm., leaving about 4cm. of working distance to the subject when the focusing scale is set to 20cm. At the wide end of the zoom the lens is 3cm. shorter but the working distance is about the same, which is puzzling. The lens can actually focus quite a bit closer, coming down to about two fingers' breadths from lens hood to subject.
Yes, the closest focus is a constant 20cm. from the focal plane to the object focused on, right through the zoom range. In manual focus there is a mechanical stop at either end of the travel of the zoom ring, but it annoys me that it doesn't stop at exactly infinity. It continues on past infinity for a bit and back out of focus. There is a bonus at the other end ,however, as the lens can focus a bit closer than 20cm.
Bengt 5
17 Jun 2016 10:21AM
Why don't you quantify these test results. "Excellent" is nice to hear but does not allow me to compare this lens to for example the new Leica Panasonic 12 mm f/1.4.
Thank You.

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