Panasonic GM1 Optics

Zoom Lens
A wider-than-average zoom for a kit lens, with above average performance.

The Panasonic 12-32mm kit lens has a 35mm-equivalent focal length of about 24-64mm, a result of the GM1's 2x "crop factor." Although zoom ratio is lower than average at only about 2.7x, this lens goes wider than most kit lenses.

Optical performance at full wide angle is very good at f/8, with sharp detail across most of the frame, though the right-hand side shows some noticeable softness and a bit of coma distortion, an indication our sample is slightly decentered. Chromatic aberration is well-controlled, because the GM1 suppresses it. At full telephoto and f/8, the lens performs even better with excellent sharpness and contrast, and just slightly soft corners on the right side. The GM1's 2x digital zoom works fairly well, but 4x reveals a lot of chroma noise and some interpolation artifacts, so digital magnification this high should be avoided except for small prints.

Macro
A larger-than-average minimum area, with good detail. Flash exposure is a little dim.

The Panasonic GM1's macro performance will depend entirely on the lens in use. However, with the 12-32mm kit lens, the Panasonic GM1 captured a larger-than-average minimum area measuring 4.61 x 3.46 inches (117 x 88 millimeters). Details are quite good across much of the frame at f/8, though corners are quite soft. (Most lenses have some additional softening in the corners at macro distances.) The popup flash throttled down a bit too much at this distance, resulting in a slightly dim exposure. Still, that's better than being strongly overexposed as some cameras tend to do.

Geometric Distortion
Average geometric distortion with the 12-32mm kit lens in JPEGs at wide angle, though strong distortion at wide angle in uncorrected RAW files.

In camera JPEGs, the Panasonic GM1's 12-32mm kit lens produces about 0.8 percent barrel distortion at wide angle, which is about average and noticeable in its images. Pincushion distortion at full telephoto is very low, at only about one pixel's worth. This is the tendency for the lens to bend straight lines outward (like a barrel -- usually at wide-angle).

To see how much correction is taking place in the camera, we convert matching RAW files from the same test shots with dcraw or RawDigger, which do not correct for distortion. As can be seen above, actual barrel distortion at wide angle is quite high at about 2.6%, while pincushion at telephoto is moderate at about 0.3%. We expect this for 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 (including Adobe Camera Raw and SilkyPix) 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, and is also sharp in the corners to begin with would be preferable, but relaxing constraints on distortion brings other benefits in the lens design, such as a more compact design.

Chromatic Aberration and Corner Sharpness
Low levels of chromatic aberration from the kit lens in JPEGs. Uncorrected RAW files show moderate amounts. Soft corners on the right-hand side even stopped down to f/8.

Chromatic Aberration. Chromatic aberration in the corners with the Panasonic GM1's 12-32mm kit lens is moderately low to very low in JPEGs. The camera's processor does a pretty good job of reducing CA in JPEGs (see below for uncorrected RAW). What color fringing there is gradually reduces in brightness and width as it approaches the center of the image, where it is almost non-existent.

Corner Softness. Our copy of the Panasonic 12-32mm kit is slightly decentered, producing soft corners on the right-hand side, while left corners are pretty sharp. The softness on the right extends into the frame about a quarter of the way, however the center is quite sharp. At full telephoto corners are sharper, but the right-hand side is still a but softer than the left, while the center is sharp.

Vignetting. Some moderate corner shading ("vignetting") is noticeable from the difference in brightness of the center versus corner crops above, at both wide angle and telephoto.

F/8: Stopped down to f/8, corner sharpness improves only slightly at wide angle, and at full telephoto, corners are actually slightly softer than at wide open. Sharpness remains excellent in the center at both ends of the zoom range, though. Vignetting (corner shading) improves quite a bit, but is still somewhat noticeable.

Chromatic Aberration Suppression. As mentioned above, the Panasonic GM1 applies lateral chromatic aberration correction to its JPEGs, as uncorrected RAW files show moderate but fairly bright green/magenta coloration at wide angle and duller blue/yellow fringing at telephoto. RAW files converted with the bundled SilkyPix software or Adobe Camera Raw are automatically corrected for lateral chromatic aberration and geometric distortion to roughly match the camera's processing.

Shading Compensation
The Panasonic GM1 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 Panasonic GM1's Shading Compensation reduces corner shading with the 12-32mm kit lens, so it's a useful feature. Shading Compensation is off by default, not available when shooting video or when burst rate is set to SH, and is not available with all lenses. It may also produce more visible noise in the periphery at higher ISOs.

Overall, well above average performance for a kit lens.

Accuracy
Excellent coverage from the LCD monitor.

The Panasonic GM1's LCD monitor proved quite accurate in record mode, showing just over 100% coverage with our Olympus 50mm f/2 reference lens. Excellent results here.