Panasonic GH2 Optics

Zoom
Very good performance with the 14-140mm O.I.S. (Optical Image Stabilized) kit lens.

The Panasonic GH2 is available bundled with a Lumix G Vario HD 14-140mm f/4-5.8 MEGA O.I.S. Micro Four-Thirds lens. This kit lens is optimized for video by incorporating a nearly silent inner focus direct-drive linear motor for continuous auto focusing as well as seamless aperture adjustment, and possesses a generous optical zoom ratio of 10x. The 35mm equivalent focal range of this lens is about 28-280mm, because of the GH2's 2x "crop factor." Results were quite good at 14mm, with only minor corner softness and fairly strong detail throughout the rest of the frame. Coma distortion in the trees was low to moderate, and chromatic aberration very low. Performance at 25mm (50mm eq.) was very good, with just a hint of softness across the frame. Results were a touch soft at the 140mm setting, with some additional softening in the corners, but no sign of visible coma distortion and very little chromatic aberration. Overall, a very good performance for a wide-angle 10x zoom and the optical image stabilization will come in handy for low-light photography, as well as for subjects shot at full zoom.

Macro
A larger-than-average area (for a recent "SLR" kit lens), with good but slightly soft detail. Flash throttles down well.

As with zoom performance, the Panasonic GH2's macro performance will depend entirely on the lens in use. However, with the 14-140mm O.I.S. kit lens set to 140mm, the Panasonic GH2 captured a slightly larger-than-average minimum area measuring 3.18 x 2.38 inches (81 x 61 millimeters).  Detail was quite good but a touch soft, with some additional softening in the extreme corners. (Most lenses have some softening in the corners at macro distances, the Panasonic GH2's kit lens has less than most.) Some light fall-off ("vignetting") is also noticeable in extreme corners. The Panasonic GH2's flash did a good job throttling down at this distance, and there was no detectable shadow from the lens barrel, which resulted in a very good exposure with the flash.

Geometric Distortion
Low geometric distortion with the 14-140mm O.I.S. kit lens in JPEGs, very high barrel distortion at wide angle in uncorrected RAW files.

When shooting JPEGs, the Panasonic GH2's 14-140mm O.I.S. kit lens produced about 0.7 percent barrel distortion at wide-angle, which is somewhat less than that produced by most cameras we've tested, though still slightly noticeable in some of its images. At the telephoto end, there was hardly one pixel of barrel distortion, practically imperceptible. 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).

Like previous Panasonic Micro Four-thirds (and compact) models, the GH2 corrects for lens distortion in JPEGs (a good thing for JPEG shooters), so we converted RAW files with dcraw which does not correct for distortion. (SilkyPix and Adobe Camera Raw both apply distortion correction automatically, so their results are similar to in-camera JPEGs.) As you can see, at wide angle the barrel distortion is very high at about 2.4 percent, however distortion at telephoto is still quite low, at only about 0.1%. (The extent of distortion correction required at wide angle may also explain some of the softness we saw in the corners at short focal lengths.)

Chromatic Aberration and Corner Sharpness
Low to moderate chromatic aberration when shooting JPEGs with the 14-140mm O.I.S. kit lens. Brighter CA in uncorrected RAW files. Some soft corners at both wide-angle and telephoto when shooting wide open.

Chromatic Aberration. When shooting JPEGs, chromatic aberration in the corners with the Panasonic GH2's 14-140mm kit lens is low to moderate at the 14mm setting, with fairly dull mostly purple fringing. At 140mm telephoto, this distortion is quite low and less noticeable. (This distortion is visible as a slight colored fringe around the objects at the edges of the field of view on the resolution target.)

Corner Softness. The Panasonic GH2's 14-140mm kit lens produced some soft corners wide open. At full wide-angle, left corners were slightly softer than the right, with the top-left being the softest, but blurring didn't extend far into the frame. There's no doubt that the geometric distortion correction that is being applied contributes to the corner softness at wide-angle. At full telephoto, only the top-right corner was reasonably sharp, while the others were quite blurry. The center was also slightly soft, and suffers from lower contrast than at full wide-angle. Some light fall-off in the corners ("vignetting") is also noticeable.

Chromatic Aberration Correction. We weren't surprised to find the GH2 reduces chromatic aberration during JPEG processing (good for JPEG shooters), as most Panasonic point & shoot and G-series do. Above are crops from uncorrected RAW files converted with dcraw. Chromatic aberration is more obvious and slightly different (cyan and red) at wide-angle and telephoto (yellow and purple) than in the corrected JPEGs, though it's still fairly well controlled especially for a 10x wide-angle zoom. (As mentioned above, SilkyPix and Adobe Camera Raw perform similar corrections to those performed by the camera, so you'll only see CA and distortion like that shown above when using a RAW converter that doesn't apply such corrections.)

Despite the soft corners, this is actually above average performance overall for a wide-angle 10x zoom lens. Keep in mind that these shots were taken with the lens wide open, and that corner sharpness and vignetting typically improve when stopping down to a smaller aperture.

Accuracy
Excellent accuracy from both the electronic viewfinder and LCD monitor.

The Panasonic GH2's electronic viewfinder and LCD monitor proved very accurate, both showing just slightly higher than 100% coverage with a low distortion 50mm f/2 prime, though there seems to be slight vertical shift. (It's difficult to tell if the shift is just measurement error or real, however it is very slight.)  Excellent results here, as you'd expect from an electronic viewfinder and LCD.