Olympus E-M1 Optics

Zoom
Wider-than-average zoom compared to most kit lenses, with excellent performance.

The new 12-40mm f/2.8 lens possesses an optical zoom ratio of about 3.3x, for a 35mm equivalent focal range of 24-80mm. While zoom ratio is typical for a kit lens, this lens goes wider than most.

Far-field performance is excellent at wide, medium and telephoto settings at f/8, with strong detail and very good contrast across the frame, though there are hints of flare visible around bright objects at wide angle. Chromatic aberration is negligible, but the E-M1 suppresses it in JPEGs. The E-M1 also offers 2x digital zoom which performs fairly well thanks to the sharp lens.

Overall, excellent performance here, especially compared to typical kit lenses. See below for comments on macro performance, geometric distortion, etc.

Macro
A small minimum area, with very good detail. Bundled flash is mostly blocked by the lens at closest distance.

As with zoom performance, the Olympus E-M1's macro performance will depend entirely on the lens in use. However, with the 12-40mm lens set to 40mm, the Olympus E-M1 captures a fairly small minimum area for a kit lens, measuring only 2.02 x 1.51 inches (51 x 39 millimeters). Sharpness is very good over much of the frame, though corners are somewhat soft. (Most lenses have some softening in the corners at macro distances.) The bundled flash seems to throttle down well at closest distance, but the lens casts a dark shadow over about two-thirds of the frame, so you'll want to use alternate lighting when shooting at closest focus with this lens.

Geometric Distortion
Low geometric distortion with the 12-40mm lens in JPEGs, much higher distortion in uncorrected RAW files.

When shooting JPEGs, the 12-40mm lens produces about 0.3 percent barrel distortion at wide angle, which is much lower than average and only slightly noticeable in some of its images. At the telephoto end, there is almost no visible distortion, only about one pixel of barrel distortion. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle) or inward (like a pincushion -- usually at telephoto).

Chromatic Aberration and Corner Sharpness
Very low chromatic aberration in JPEGs as the E-M1 suppresses it. Mild to moderate corner softening wide open.

Chromatic Aberration. Chromatic aberration is very low, as the E-M1 is the first Olympus Micro Four-Thirds model that suppresses lateral chromatic aberration in JPEGs. See below for uncorrected results.

Corner Softness. Corners are only very slightly soft wide open at wide angle while the center is sharp, which is excellent performance, especially since the lens is both wider and faster than a typical kit lens. At full telephoto, the top corners are sharp, but the bottom corners are moderately soft, with the bottom right the softest. The center exhibits good sharpness.

Vignetting. There's also some moderate vignetting (corner shading) at both wide angle and telephoto at maximum aperture, as indicated by the darker corner crops compared to the center. However, keep in mind this is a constant f/2.8 aperture lens, so performance here is actually pretty good.

Chromatic Aberration. With the aperture stopped down to f/8, chromatic aberration remains very low, as expected.

Corner Softness. Corner sharpness is quite good at both wide angle and telephoto when stopped-down to f/8, with the improvement at telephoto more dramatic than wide angle.

Vignetting. Vignetting also improves at f/8, to the point of being negligible.

Overall, excellent optical performance for a wide-angle zoom.

In-camera Lens Corrections

Geometric Distortion Correction
Like all Micro Four-Thirds cameras, the E-M1 automatically applies geometric correction to JPEGs that can't be disabled.

To see how much correction is taking place in the camera, we converted RAW files with dcraw, which does not correct for distortion. As you can see at wide angle, barrel distortion is very high at about 2%, though pincushion distortion at telephoto is a low 0.3%. We expect to see high distortion at wide angle from smaller interchangeable lenses though, so it's nothing to be too concerned about unless you are using a RAW converter which does not understand the embedded "opcodes" to perform distortion corrections automatically. Most RAW converters these days are capable of applying distortion correction automatically, as specified by the manufacturer. There is however going to be some loss of resolution in the corners as a result of such correction, because pixels in the corners of the frame are being "stretched" to correct for the distortion. Obviously, a lens that doesn't require such correction that is also sharp in the corners to begin with would be preferable, but relaxing constraints on barrel and pincushion distortion likely brings other benefits in the lens design, such as cost, size and weight.

Chromatic Aberration Suppression
The Olympus E-M1 now suppresses lateral chromatic aberration automatically in JPEGs

As mentioned above, the E-M1 is the first interchangeable lens camera from Olympus that corrects for lateral chromatic aberration in JPEGs. Other companies have been doing this for a while, and we're glad to see Olympus has finally implemented it as well. As you can see from comparing the in-camera JPEGs to uncorrected RAW crops above, the E-M1's chromatic aberration suppression is very effective at removing almost all the lateral chromatic aberration in our 12-40mm test shots, though there wasn't a lot of C.A. to suppress to begin with, particularly at the telephoto end.

Shading Compensation
The Olympus E-M1 features optional Shading Compensation to reduce vignetting in JPEG images.

Mouse over the links above to compare thumbnails, and click on the links to load the full resolution images.

As you can see, the Olympus E-M1's Shading Compensation reduces corner shading with the 12-40mm lens, so it's a useful feature particularly with fast and/or wide lenses. Note that Shading Compensation is off by default, and is not available with all lenses. It may also produce more visible noise in the periphery at higher ISOs.

Accuracy
Excellent accuracy from the EVF and LCD monitor.

The Olympus E-M1's electronic viewfinder and LCD monitor both proved quite accurate in record mode, showing just over 100% coverage with our Olympus Zuiko Digital 50mm f/2.0 prime. Excellent results here, though not a surprise given previews are derived directly from the image sensor.