Olympus M.Zuiko 25mm f/1.8 ED Premium Lens Review

Olympus M. Zuiko 25mm f/1.8 Performance

At f/1.8, sharpness in the centre of the frame is already excellent, and clarity towards the edges of the frame is good. Stopping down improves performance across the frame, with sharpness in the centre reaching outstanding levels between f/2 and f/8. Clarity towards the edges of the frame reaches excellent levels between f/5.6 and f/8.

MTF

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 hovering around the half pixel-width level towards the edges of the frame between f/1.8 and f/11. This low level of fringing should be difficult to spot, even in large reproductions of images, or harsh crops from the edges of the frame.

CA

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 well controlled for a fast aperture standard lens. At f/1.8 the comers are 1.21 stops darker than the centre of the image and stopping down to f/5.6 results in visually uniform illumination across the frame.

Distortion is well corrected in camera, but even so, Imatest was only able to detect 1.07% barrel distortion. This low level of distortion should pose few issues and the distortion pattern is uniform across the frame, which should make applying corrections in image editing software afterwards, relatively straightforward.

A deep circular 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.

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