Olympus E-PM1 Optics

Zoom
Typical zoom range for a kit lens, with very good performance.

The Olympus PEN E-PM1 is available bundled with an Olympus M.ZUIKO 14-42mm f/3.5-5.6 II R Micro Four Thirds lens. The kit lens possesses a very typical optical zoom range of 3x, and the 35mm equivalent focal range is about 28-84mm, because of the E-PM1's 2x "crop factor." Results were very good at 14mm, with strong detail and good contrast across the frame, though some chromatic aberration can be seen in the corners. Results were also very good at the 42mm setting, with good sharpness and contrast, as well as lower levels of chromatic aberration. Overall, well above average performance here for an inexpensive kit lens. See below for comments on macro performance, geometric distortion, corner softness, etc.

Macro
An average sized minium area, with slightly soft detail. Flash exposure is dim.

As with zoom performance, the Olympus PEN E-PM1's macro performance will depend entirely on the lens in use. However, with the 14-42mm II kit lens set to 42mm, the Olympus E-PM1 captured a fairly average minimum area measuring 2.87 x 2.15 inches (73 x 55 millimeters). Details were quite good, just a touch soft across the frame, and there's very little additional softening in the extreme corners. (Most lenses have some softening in the corners at macro distances, and the Olympus E-PM1's kit lens has much less than most.) Extreme corners showed a very small amount of light falloff, though that's not unusual. The built-in flash throttled down too much at this close distance, resulting in a underexposed image.

Geometric Distortion
Low to moderate geometric distortion with the 14-42mm II kit lens in JPEGs, much higher than average distortion in uncorrected RAW files.

When shooting JPEGs, the Olympus PEN E-PM1's 14-42mm kit lens produced about 0.6 percent barrel distortion at wide-angle, which is actually a little better than average and only slightly noticeable in some of its images. At the telephoto end, there was almost no visible distortion, less than one pixel. 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).

To see how much correction is taking place in the camera, we converted RAW files from the above shots with dcraw, which does not correct for distortion. As you can see, at wide-angle, the barrel distortion is very high at about 2.5%, though pincushion distortion at telephoto is very low, almost nil. We expect to see high distortion at wide-angle from smaller interchangeable lenses though, so it's nothing to be 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's going to be some loss of resolution 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, and 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 and Corner Sharpness
Moderate chromatic aberration at wide-angle with the 14-42mm II kit lens; lower levels at full telephoto. Some mild to moderate corner softening at wide open.

Chromatic Aberration. Chromatic aberration in the corners with the E-PM1's 14-42mm II kit lens was moderate and slightly noticeable at wide-angle (14mm) when wide-open (maximum aperture). At full telephoto (42mm), C.A. was lower, and not as noticeable.  In both cases, the color fringing gradually reduces in brightness and width as it approaches the center of the image, where it is practically nonexistent.

The Olympus E-PM1 does not appear to be reducing C.A. in its JPEGs, as uncorrected RAW files have similar amounts.

Corner Softness. The Olympus E-PM1's 14-42mm kit lens produced only slightly soft corners at full wide angle, and the center was very sharp. Corners we also only slightly soft at full telephoto, though the center was not as sharp as wide-angle. There's also some mild vignetting (corner shading), as indicated by the darker corner crops compared to the center.

Very good performance for a kit lens here, especially considering the lens was wide-open for these shots. (Corner sharpness generally improves when a lens is "stopped-down" a couple of f-stops below full aperture. See below.)

Chromatic Aberration. With the aperture stopped down to f/8, chromatic aberration in the corners is slightly lower.

Corner Softness. Corner sharpness improved both wide-angle and telephoto when stopped-down to f/8, and sharpness improved in the center at full telephoto as well. Vignetting also improved to the point of being negligible. Again, very good performance from the kit lens.

Accuracy
Very good accuracy from the LCD monitor.

The Olympus PEN E-PM1's LCD monitor proved very accurate in record mode, showing just slightly over 100% coverage with our Olympus Zuiko Digital 50mm f/2.0 low distortion prime. Very good results here. Since the electronic viewfinder is optional, we didn't test its accuracy with the E-PM1, but we expect similar accuracy.