Panasonic GX1 Optics

Zoom Lens
A typical zoom ratio for a kit lens, with fair performance.

The above shots were taken with the Lumix G X VARIO PZ 14-42mm f/3.5-5.6 Power O.I.S. Micro Four Thirds zoom lens. The 35mm equivalent focal length is about 28-82mm, a result of the GX1's 2x "crop factor." Results at full wide-angle were pretty good at f/8, but detail was just a touch soft across most of the frame, with hints of flare around bright objects. Extreme corners exhibited mild to moderate blurring and minor coma distortion. Chromatic aberration is well controlled at all focal lengths (the GX1 suppresses C.A.). Performance at medium focal length was also good, but again with a hint of softness across the frame. At full telephoto, the lens was a little softer across the frame, and there was some noticeable vignetting (shading) in the corners. The GX1's digital zoom mode showed typical loss of fine detail for such a high magnification.

Overall, a fair performance for a kit lens, but the X lens is pricier than most 3x kit lenses (it lists for about US$400 when bought separately), so we were hoping for better optical performance at this price point, despite its compact size and power zoom feature.

Note: be sure to read our discussion of the blur issue we ran into at telephoto with this lens, induced by shutter vibrations at certain shutter speeds.

Macro
A larger than average minimum area, with somewhat soft detail and strong corner shading. Flash throttled down well, though.

The Panasonic Lumix DMC-GX1's macro performance will depend entirely on the lens in use. However, with the 14-42mm X kit lens, the Panasonic GX1 captured a much larger than average minimum area measuring 3.79 x 2.85 inches (96 x 72 millimeters). Detail was good but a little soft across the frame at f/8, with additional softening in the corners. (Most lenses have some additional softening in the corners at macro distances.) There was also some fairly strong vignetting or corner shading in the extreme corners, much more than we're used to seeing especially stopped-down to f/8. The popup flash had no trouble throttling down at this distance, resulting in a pretty good exposure, though corner shading was still visible. However, sharpness in the center of the frame was better in the flash shot.

Geometric Distortion
Low geometric distortion with the 14-42mm X kit lens in JPEGs, though strong distortion in uncorrected RAW files.

When shooting JPEGs, the Panasonic GX1's 14-42mm kit lens produced just over 0.3 percent barrel distortion at wide-angle, which is much less than average and hardly noticeable in its images. Pincushion distortion at full telephoto was about 0.2 percent, also lower-than-average and not very noticeable. 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 converted a RAW file from the above shot with dcraw, which does not correct for distortion. As can be seen above, the actual barrel distortion at wide-angle is quite high at about 2.0%, while pincushion at telephoto was also fairly high, at about 0.8%. 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 very compact design.

Chromatic Aberration and Corner Sharpness
Low to moderate levels of chromatic aberration from the kit lens in JPEGs. Uncorrected RAW files show higher amounts. Corners at wide-angle were soft wide-open, but improve when the lens is stopped-down. Our copy of the lens was soft at full telephoto, even stopped-down to f/8.

Chromatic Aberration. Chromatic aberration in the corners with the Panasonic Lumix DMC-GX1's 14-42mm X kit lens is low to moderate in terms of pixel count in JPEGs, being somewhat exacerbated by the blurring, but coloration is fairly dull and bluish. The camera's processor does a pretty good job of reducing CA in JPEGs (see below for uncorrected RAW). As usual, color fringing gradually reduces in brightness and width as it approaches the center of the image, where it is almost non-existent.

Corner Softness. The Panasonic GX1's 14-42mm X kit lens produced moderate blurring in all four corners wide-open at f/3.5, though softness doesn't extend very far into the frame. The center was fairly sharp. Corners were even softer at full telephoto, and the center was quite soft as well. (This is not focus error as multiple trials with manual focus didn't improve sharpness.) Some moderate corner shading ("vignetting") is also noticeable from the difference in brightness of the center versus corner crops above.

Stopped down to f/8, corner sharpness improved somewhat, but full telephoto was still soft across the frame, with slightly softer corners. Vignetting (corner shading) improved quite a bit, but is still slightly noticeable.

Chromatic Aberration Correction. As mentioned above, the Panasonic GX1 applies chromatic aberration correction to its JPEGs, as uncorrected RAW files show much more distinct green and magenta coloration. RAW files converted with the bundled SilkyPix software or Adobe Camera RAW are automatically corrected for CA and geometric distortion, so we used dcraw for the uncorrected conversions above right.

Shading Compensation
The Panasonic GX1 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 GX1's Shading Compensation reduces corner shading with the 14-42mm X 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.

Accuracy
Excellent coverage accuracy from the LCD monitor.

The Panasonic GX1's LCD monitor proved quite accurate in record mode, showing just a touch over 100% coverage with our low-distortion Olympus 50mm f/2 reference lens. Excellent results here.