Panasonic 14-140mm f/4-5.8 ASPH MEGA OIS LUMIX G VARIO HD

SLRgear Review
June 3, 2009
by Andrew Alexander

The Panasonic 14-140mm ƒ/4-5.8 was released with the GH-1 as its kit lens. The lens is significant in that it features an HD designation, incorporating a new drive motor that allows for ''fast and accurate contrast auto focus.'' The lens can also be purchased separately from the GH-1 kit. Mounted on the GH-1, the 14-140mm produces an effective field of view of 28-280mm in 35mm film camera terms.

The 14-140mm isn't a ''constant'' lens, in that as you increase the focal length, the maximum aperture size decreases, however the minimum aperture stays the same. The following table reflects the change in aperture with focal length:

The Panasonic 14-140mm ƒ/4-5.8 uses 62mm filters, and comes with a petal-shaped lens hood.

Sharpness
When used at its widest aperture, the 14-140mm exhibits some mild corner softness when used at either wide-angle (14-18mm) or at telephoto (100-140mm). For the rest, the image is remarkably sharp, even at the widest aperture, with performance of less than 2 blur units. Wide open you'll see the best performance using the lens at around 50mm (ƒ/5.5 at this focal length), with a sharpness rating of just over 1 blur unit.

There's not much of an increase in sharpness performance by stopping down to ƒ/5.6 - by 50mm that's practically the maximum aperture anyway - but at 14-18mm the corners become a bit less soft. At ƒ/8 there's a bit more improvement in the corners, and at 50mm it's tack-sharp.

Diffraction limiting seems to set in at ƒ/11, with a slight across-the-board decrease in image sharpness. Performance in the mid-range (24-100mm) is still good, and even at ƒ/16 we still note performance in the range of 2 blur units. The corners of wide-angle and telephoto suffer again at ƒ/11 and smaller, and at ƒ/22, everything is slightly soft with ratings of around 3-5 blur units.

So, in the focal length extremes (wide-angle and telephoto) there's some slight softness in the corners, but this is somewhat mitigated by stopping down to ƒ/5.6 or ƒ/8. In the mid-range the lens produces excellent results, even when used wide open.

Chromatic Aberration
On the whole, chromatic aberration is well-controlled; average performance (CA visible throughout the image) is very low, and maximum CA is only visible in the corners with the lens' focal length set to below 70mm (where it's still well-controlled) or to 140mm, where it's fairly noticeable. It's easier just to look at our sample images to see the CA effect, but for the most part, it isn't really an issue.

Shading (''Vignetting'')
The GH-1 continues to foil our software in order to calculate results for corner shading. From a visual examination of our sample images, the trend of mid-range performance seems to continue - I don't see any corner shading when the lens is used around the 50mm mark, but there is some slight shading at either the wide-angle end or at full telephoto. In either case, there doesn't appear to be enough falloff to write home about.

Distortion
We know that the G1 and GH1 cameras apply some post-processing to correct for distortion, which explains the dramatic results we see for distortion. In particular, while there is some barrel distortion when used at wide angle (14-18mm), distortion completely disappears between 18-140mm.

Autofocus Operation
The GH-1 uses an electrical autofocus system, enabling fast and silent focusing. The lens was able to focus between infinity, close-focus and back again in under a second, and small focus changes happened extremely quickly. This is very impressive performance, especially considering it's a contrast autofocus detection method.

Macro
Macro performance is quite good, with a maximum 0.4x magnification rating (1:2.5 reproduction ratio). The lens' minimum close-focusing distance is 50 cm (just over a foot and a half).

Build Quality and Handling
Panasonic has led the way with micro-four-thirds lenses, and miniaturization is the name of the game. For a zoom lens with a 10x rating the lens is quite small, and comparatively light - it weighs just 460 grams (just over a pound). The lens is constructed of dense plastic, with an grey / black matte finish. The lens mount is metal, and the 62mm filter threads are plastic.

The lens has few controls to speak of, other than the zoom and focus rings. A single switch is available, which controls the Mega Optical Image Stabilization (''Mega O.I.S.''), turning it on or off. The lens has no distance scale or depth-of-field markings.

The zoom ring is the larger of the two, a thick rubber with raised rubber ridges. It is 7/8'' wide and is mounted closer to the lens mount. It has about 40 degrees of turning action between wide-angle and full telephoto, and doing so will extend the lens 2 3/8'', almost doubling the length of the lens to 5 1/8''. Add on the petal-shaped lens hood (1 5/8'') and you have a possible total length of 6 3/4''. The lens doesn't have any problems with zoom creep, and the zoom action is nicely cammed, providing a smooth turn that has just the right level of firmness. The petal-shaped lens hood reverses onto the lens for storage.

The focus ring is composed of plastic with raised ribs, and is 1/2'' wide. The focus ring will turn forever in either direction, with no hard stops to indicate a focus limit. Thus it's hard for us to determine how many degrees of ''focus action'' are available in manual focus, though manual focus is handled extremely well by the camera. Just turning the focus ring brings up a magnified view section on the LCD, which assists greatly.

Panasonic has built Mega Optical Image Stabilization into the lens, useful for countering the effects of shaky hands holding the camera.

Alternatives

Panasonic 14-150mm ƒ/3.5-5.6 ASPH Leica D VARIO-ELMAR ~$1,000
The regular four-thirds variant of this lens, the 14-150mm also features optical image stabilization, and should be usable on the GH-1 with the four-thirds to micro-four-thirds adapter. The lens is just slightly faster (ƒ/3.5-5.6 instead of ƒ/4-5.8), but is also slightly larger and heavier. We haven't yet tested this lens.

Olympus 18-180mm ƒ/3.5-6.3 Zuiko Digital ~$450
This lens should be usable on the GH-1 with the use of an adapter. Though it won't provide quite the wide-angle performance, it does offer greater telephoto capability, at the cost of a slightly slower lens in terms of aperture performance. The lens weighs about the same, but doesn't feature image stabilization. We haven't yet tested this lens.

Conclusion
Panasonic has done well with this lens. The ability to autofocus during movie mode was an absolute must for the saleability of the GH-1, which required a fast, silent autofocus mechanism; in this capacity, the 14-140mm delivers handily. Optically, the lens is no slouch, providing pleasantly sharp images in almost any situation, and when used in the mid-range (24-100mm) and stopped down slightly, images are very sharp indeed. In the extreme ends - wide-angle or full telephoto - the lens shows slight faults: some chromatic aberration, distortion and corner softness, but nothing to the extreme. The only reservation I might have about the lens is its aperture capacity: by 50mm, its maximum aperture is ƒ/5.6, meaning the heavy lifting for low-light images will be done by the camera with higher ISO settings. Used with reasonable light levels, this really isn't a factor.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.