Panasonic 45-200mm f/4-5.6 MEGA OIS LUMIX G VARIO

(From Panasonic lens literature) The new LUMIX G VARIO 45-200mm/F4.0-5.6/MEGA O.I.S. lens offers a zoom range of 45-200mm (35mm equivalent: 90-400mm) while achieving minimum aberration at all focal length, high-contrast representation and high color reproduction by implementing 3 ED lens elements.

SLRgear Review
November 23, 2008
by Andrew Alexander

Update: by processing RAW files produced by the G1, we have determined that the G1 does apply some measure of post-processing correction for chromatic aberration, light falloff and distortion. So on a body other than the G1, your results may vary.

The 45-200mm ƒ/4-5.6 OIS is the second lens released by Panasonic in its line of Micro Four-Thirds compatible lenses.

When mounted on a micro four thirds compatible camera, the size of the sensor produces a 2x crop factor, meaning an equivalent field of view of 90-400mm in 35mm film terms. Panasonic is one of the early pioneers in optical image stabilization systems, so it's no surprise that the lens features its Mega O.I.S. technology to reduce the effect of camera shake.

The 45-200mm isn't a ''constant'' lens, in that as you increase the focal length, the maximum aperture size decreases, though the minimum aperture remains the same. The following table reflects the change in aperture with focal length:

The Panasonic 45-200mm ƒ/4-5.6 OIS uses 52mm filters, and comes with a circular-shaped lens hood.

Sharpness
The 45-200mm ƒ/4-5.6 OIS isn't quite as good a performer as the 14-45mm ƒ/3.5-5.6, but it still provides acceptable results.

Let's start with the lens' optimal point of operation. Stopped down slightly to ƒ/5.6, at 61mm, we see 1 blur unit in the center of the frame and 2 blur units in the right-hand corners (a little less on the left-hand side, suggesting our copy is slightly de-centered). That's the best-case scenario, which is actually very good, but it shows that the lens is optimized for situations of adequate light, as ƒ/5.6 isn't terribly fast. Below 100mm, when used wide-open at (ƒ/4-5.6) the lens shows off well in the center of frame, with significant corner softness at wide-angle (14mm), improving as the focal length increases. At the mid-range (~72mm) we see quite good performance, marred only by the de-centered nature of the lens: 1 blur unit in a large central portion of the frame, with only slight corner softness. I suspect in a better copy this would be the optimal setting for the lens.

Zoomed out beyond 100mm, the lens begins to show some generalized softness, which becomes most apparent when used at 200mm; here, the lens shows 3-5 blur units - 3 in the center, 5 in the corners - suggesting that the lens produces its better images when used at the wider angles.

Stopped down to ƒ/8, even ƒ/5.6 at the mid-range (50-70mm) produces the best results for the lens. Diffraction limiting sets in at ƒ/11, but even at ƒ/16, the sharpness doesn't exceed 2 blur units until you zoom in past 100mm. Performance at ƒ/22 is noticeably soft, again 3-5 blur units up until 100mm - and 5-7 units above 100mm.

So when used below 100mm, the lens can produce some very good results, but you're better off shooting slightly stopped down, if possible. Telephoto results are a bit mixed, especially if you go into 200mm territory.

Chromatic Aberration
General chromatic aberration isn't really a factor for the lens until you zoom in past 150mm, and stop down past ƒ/16. The worst example is 200mm at ƒ/22, where we see 3/100ths of a percent of frame height of chromatic aberration, present in the entire image. CA in the corners is prominent in more practical settings, but if you can keep the lens at ƒ/8, chromatic aberration won't be a factor in images produced with this lens. Outside of that, CA may be a consideration.

At wide-angle settings (45-60mm) CA is quite noticeable when the lens is used wide open (ƒ/4-4.1), reaching over 9/100ths of a percent of frame height in the corners. This improves dramatically as the lens is stopped down, until it drops below 2/100ths at ƒ/8. 100mm produces the best results, with less than 3/100ths of a percent of frame height of CA in the corners, regardless of the aperture. Climbing above 100mm, corner CA performance degrades as the lens is stopped down.

So, in a nutshell: to avoid chromatic aberration, you can:

1. Shoot at 100mm, at any aperture.
2. Below 100mm, shoot at ƒ/8-ƒ/22.
3. Above 100mm, shoot at ƒ/4-ƒ/11.

Shading (''Vignetting'')
Unfortunately, or testing software couldn't contend with the G1's image files when it came to calculating corner shading. Looking at the sample images is fairly useful in this regard: to my eye, corner shading isn't an issue, but then we've noted that the G1 is doing some post-processing correction, so how the lens actually performs is anyone's guess.

Distortion
The 45-200mm ƒ/4-5.6 is also very good at providing undistorted images. There is a hint of pincushion distortion in the corners above 60mm, but this doesn't exceed 0.1%; at 50mm, distortion of any stripe is almost non-existent.

Autofocus Operation
The 45-200mm ƒ/4-5.6 focuses very quickly on the G1 body, and locks onto the target well. The focus action is virtually silent. A setting on the G1 allows you to override autofocus results by just turning the focus ring; this setting can also ensure that autofocus results aren't affected by an accidental turn of the focus ring.

Macro
At 0.38x magnification (almost 1:2.6 reproduction), the Panasonic 45-200mm ƒ/4-5.6 offers fairly useful macro capabilities. Minimum close-focusing distance is just over three feet (1m).

Build Quality and Handling
The Panasonic 45-200mm ƒ/4-5.6 lens is made of a two-tone dense plastic, with a metal lens mount. The micro four thirds format allows the lens to be very compact, and fits the small G1 camera well. At just 100mm long (under 4 inches) and 380 grams (just over 13 ounces), this is indeed a tiny product, especially considering the range of focal lengths it covers.

The lens takes 52mm filters. It isn't adorned with much in the way of instrumentation: lens markings for relevant focal lengths and a switch to control image stabilization are the only features other than the zoom and focus rings. The Mega OIS stabilization has a two-stage setting for ON and OFF.

Manual focus is controlled by a ribbed hard plastic ring about a 1/2-inch wide, set in front of the zoom ring. There are no stops at either the close or infinity end of the focus spectrum. The G1, like other 4/3-mount manufacturers, controls focus electrically, with the lens receiving electrical instructions from the ring, and responding mechanically to focus forward or backward. Manual focus operation is very intuitive on the G1; if enabled via a custom function, the image is magnified to provide high detail for critical focus. During focus the forward lens element doesn't rotate, allowing for painless use of filters.

Zooming through the lens' range of 45-200mm is accomplished with the zoom ring, almost an inch wide and made of a dense rubber. The ring uses sharp, squared ridges that offer good grip. The ring is just stiff enough to prevent any form of zoom creep, but it still very smooth and easy to turn. About 45 degrees of turning will move you through the lens' zoom range. At 45mm, the lens has extended by 1 1/2 inches.

The lens hood provided with the 45-200mm adds about 2 1/4 inches to the overall length of the lens; it's a deep circular shape, and attaches with a bayonet-style mount. It's ribbed on the inside to reduce stray light, and reverses to be attached to the lens for storage.

The Mega OIS feature of the lens activates very quickly, and is virtually silent in its operation. We're still in the stages of finalizing our image stabilization test results, but we can say that the lens stabilization is consistent with what we've come to expect from Panasonic. Three modes of image stabilization are offered in the G1: continuous mode, a mode that operates only when the shutter is depressed, and a panning mode that corrects vertical movement only.

Alternatives

It's still early days for the Micro Four Thirds system, so there isn't anything out of the box that counts as an alternative. However, the Four Thirds designers smartly created an adapter to allow regular four-thirds lenses to be mounted, offering backwards-compatibility for G1 users.

Any of these alternative recommendations should be taken with a large grain of salt; who knows what effects to image quality will occur when using the regular 4/3rds - micro-4/3rds adapter.

If you do want to use the adpater to mount Olympus lenses to the G1, you'll need to update your camera with a firmware update provided by Olympus: see the end of this article for the link.

Panasonic 14-150mm ƒ/3.5-5.6 ASPH Leica D VARIO-ELMAR ~$1,000
We haven't yet tested this lens, but with the 4/3 - micro 4/3 adapter this lens could become the definitive walk-around combination for the G1. Given that performance of the 45-200mm isn't spectacular, the 14-150mm may be a reasonable alternative to having to carry around two lenses. Downsides: it's heavier, takes larger 72mm filters, and is fairly expensive.

Olympus 40-150mm ƒ/4-5.6 ED Zuiko Digital ~$280
With a firmware update and the 4/3 - micro 4/3 adapter, the Olympus 40-150mm becomes an option for the G1. The lens is much sharper than the Panasonic 45-200mm, but of course the maximum focal length is 150mm, rather than 200mm. The Panasonic lens is a bit better at counter-acting CA, corner shading and distortion, but we still don't know how much of that is the lens and how much is the G1.

Conclusion
The 45-200mm makes a good companion to the 14-50mm ƒ/3.5-5.6, but it isn't quite the star performer as that lens. The lens does provide good image performance when used in a fairly wide array of focal length - aperture combinations, but in certain scenarios you may have to trade off image sharpness for CA. As well, telephoto performance above 150mm is distinctly so-so. But, as the second lens in the micro four-thirds camp, it fares pretty well.

A postscript to this review: in our test of the G1, we have our suspicions that Panasonic may be doing post-capture processing to reduce chromatic aberration and distortion, thus improving the performance of the lens. But we won't know for sure until someone comes up with a RAW converter for the G1.

Finally, as noted earlier, Olympus has made available a series of firmware updates to enable Olympus 4/3rds lenses to be compatible with the Panasonic G1. Both the G1 and the relevant lenses must be updated, all of which is done through the camera. If this applies to you, here's the link to Olympus' firmware update site:

Olympus Firmware update for G1 / 4/3rds lenses

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.