Panasonic GX7 Optics

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

The 14-42mm II kit lens has a 35mm-equivalent focal length of about 28-82mm, a result of the GX7's 2x "crop factor." Results at full wide angle are pretty good at f/8, with sharp detail across most of the frame, though with hints of flare around bright objects. Extreme corners exhibit mild blurring and minor coma distortion, though this scene isn't great for judging corner performance (see below for lab results). Chromatic aberration is well-controlled, because the GX7 suppresses it. At full telephoto and f/8, the lens is a little softer across the frame with lower contrast, though performance is not bad for an inexpensive kit lens (Panasonic is only charging ~$100 more for the lens when bundled with the camera). The GX7's 2x digital zoom works fairly well, but 4x shows a lot of chroma noise and some interpolation artifacts, so digital magnification that high should be avoided except for very small prints.

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

The Panasonic Lumix DMC-GX7's macro performance will depend entirely on the lens in use. However, with the 14-42mm kit lens, the Panasonic GX7 captured a larger than average minimum area measuring 3.68 x 2.76 inches (93 x 70 millimeters). Detail is 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 way overexposed as some cameras do.

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

In camera JPEGs, the Panasonic GX7's 14-42mm kit lens produces about 0.4 percent barrel distortion at wide angle, which is much less than average and hardly noticeable in its images. Pincushion distortion at full telephoto is about 0.3 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 matching RAW files from the same test shots 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 2.1%, while pincushion at telephoto remains the same 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 higher amounts. Some soft corners even stopped down to f/8.

Chromatic Aberration. Chromatic aberration in the corners with the Panasonic GX7's 14-42mm kit lens is 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). At wide angle, color fringing gradually reduces in brightness and width as it approaches the center of the image, where it is almost non-existent. At full telephoto, some reddish fringing remains, even in the center.

Corner Softness. The Panasonic GX7's 14-42mm kit lens produced soft corners with reduced contrast in all four corners wide-open at f/3.5, though softness doesn't extend very far into the frame. The center is fairly sharp. At full telephoto, corners are fairly sharp on the left-hand-side, but the ones on the right are softer with lower contrast, and the center is also somewhat soft with lower contrast.

Vignetting. Some moderate corner shading ("vignetting") is noticeable from the difference in brightness of the center versus corner crops above.

F/8: Stopped down to f/8, corner sharpness improved only slightly at wide angle (much of the softness is likely due to the strong distortion correction). At full telephoto, contrast and sharpness improved but the bottom right corner is still softer than the others. Vignetting (corner shading) improved quite a bit, but is still somewhat noticeable.

Chromatic Aberration Suppression. As mentioned above, the Panasonic GX7 applies lateral chromatic aberration correction to its JPEGs, as uncorrected RAW files show fairly bright green/magenta coloration at wide angle and blue/red 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, so we used dcraw for the uncorrected conversions above right.

Shading Compensation
The Panasonic GX7 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 GX7's Shading Compensation reduces corner shading with the 14-42mm 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, about average performance for a kit lens, but given Panasonic is only charging about US$100 for it when purchased with the camera, it's actually a pretty good value.

Accuracy
Excellent coverage accuracy from the EVF and LCD monitor.

The Panasonic GX7's EVF and LCD monitor proved quite accurate in record mode, showing essentially 100% coverage with our low-distortion Olympus 50mm f/2 reference lens. Excellent results here.