Panasonic Lumix DMC-G3 Optics
Panasonic LUMIX G Lenses
The Panasonic G3 is compatible with any Micro Four Thirds lens, with Panasonic, Olympus, and third parties together offering approximately thirty lens models at the time of writing (September 2011). Panasonic has dubbed the bulk of their Micro Four Thirds lenses "LUMIX G," and the company has released (or is on the verge of releasing) 14 models to date. Eight of these are zooms, as identified by their Vario branding, while six are primes -- among these, one macro and one 3D lens. Of the Panasonic lenses on offer, two are available in a kit along with the G3. Both with-lens kits include the 14-42 mm zoom, and one adds the 45-200mm zoom.
The Panasonic Lumix G 14 mm / f/2.5 Asph. is the company's smallest Micro Four Thirds lens. Despite featuring a metal mount, it's also the lightest by some margin -- at least, with the sole exception of the unusual 3D lens -- weighing just under two ounces. With a maximum aperture of f/2.5, it's among the brightest, bettered in Panasonic's own lineup only by the 25mm f/1.4 and 20mm f/1.7 primes. (These three lenses would complement each other nicely, with 35mm-equivalent focal lengths of 28mm, 40mm, and 50mm respectively.)
The Lumix G X Vario PZ 14-42mm f/3.5-5.6 Asph. Power O.I.S, meanwhile, is the lightest zoom lens in the line, and offers equivalent focal lengths from 28-84mm. It's one of the first two Power Zoom lens models in Panasonic's lineup, and so can provide relatively smooth, shake-free zooming and manual focusing during video capture. That's because there's no need to adjust your grip to turn a zoom or focus ring, with both instead controlled by fly-by-wire rocker switches. It also features a collapsing design that makes it significantly smaller and lighter than the earlier Lumix G Vario 14-42mm f/3.5-5.6 Asph. Mega O.I.S, and includes an updated stabilization system that provides a greater degree of correction during video capture than is available for stills. To save weight and cost, both 14-42mm lenses forgo an IS switch, with stabilization instead being enabled or disabled through the camera's menu system. The older G Vario lens further uses a plastic lens mount to reduce cost, instead of featuring a metal one. As you'd expect, it's significantly cheaper than the power zoom version, and it will also be preferable to photographers wanting a mechanical zoom ring or a focus ring (albeit still fly-by-wire).
The Lumix G Vario 7-14mm f/4.0 Asph. offers the widest field of view among Panasonic's Micro Four Thirds zooms, and is also unique as the company's only zoom to offer a constant maximum aperture -- but no stabilization. The Lumix G Vario 14-45mm f/3.5-5.6 Asph. Mega O.I.S. is just a fraction smaller and has ever so slightly more reach than the 14-42mm, with an equivalent range of 28-90mm, but weighs almost 20% more.
The Lumix G Vario HD 14-140mm f/4.0-5.8 Asph. Mega O.I.S. has by far the most reach of Panasonic's Micro Four Thirds lenses, with 35mm-equivalent focal lengths ranging from 28-280mm, for a 10x zoom range. It's the only non-power zoom lens carrying the "HD" badge, which indicates that it's designed for movie recording. This comes thanks to two specific features -- a nearly silent inner focus direct-drive linear motor for continuous auto focusing, and a seamless aperture adjustment.
The other power zoom model is the Lumix G X Vario PZ 45-175mm f/4.0-5.6 Asph. Power O.I.S., which has rocker-controlled fly-by-wire zoom and focus control, like the 14-42mm PZ, but doesn't feature a collapsing design. 35mm-equivalent focal lengths range from 90-350mm, for a 3.9x zoom. The Lumix G Vario 45-200mm f/4.0-5.6 Mega O.I.S., has a slightly greater 4.4x zoom range, and reaches out to a stronger 400mm-equivalent telephoto. The Lumix G Vario 100-300mm f/4.0-5.6 Mega O.I.S. offers the strongest telephoto of all, though, at 600mm equivalent. It's also the heaviest of Panasonic's offerings, at a little over 1.1 pounds, not to mention the largest, at just under five inches in length when retracted, with a maximum diameter of 2.9 inches.
Finally, the Lumix G Fisheye 8mm f/3.5 offers the widest field of view, while the Leica DG Summilux 25mm f/1.4 Asph. and Leica DG Macro-Elmarit 45mm f/2.8 Asph. Mega O.I.S. have the tightest fields of view among the primes. The latter pair are also the only models not carrying Lumix G branding. The 45mm is the only prime in the group to offer image stabilization. The Lumix G 12.5mm f/12 is pretty much unique, not only within Panasonic's line, but for Micro Four Thirds as a whole, allowing simultaneous recording of two low-resolution images (1.9-2.9 megapixels on the G3, depending on the aspect ratio) with slightly differing field of view, which are combined to create a single 3D image for viewing on compatible displays.
Overall, we've found generally Panasonic's lenses to be of very good quality. Helped in part by in-camera processing which reduces both geometric distortion and chromatic aberration, they've consistently delivered excellent optical results in our testing and use. Lens quality is an important part of the decision whether or not to adopt a new camera system, and on that score, the Panasonic G-series does very well.
Quite a range of other options are available from Olympus, Panasonic's partner in the Micro Four Thirds format, or are on the horizon from a variety of companies. Olympus currently offers eight Micro Four Thirds-mount lenses (or nine if you count the two 14-42mm variants), of which three are primes, and the remainder are zooms. In February 2011, third party lens maker Sigma Corp. announced that it intends to market lenses for the Micro Four Thirds format, although it had yet to announce specifics as of September 2011. Fans of manual focus will also find interesting the fact that several famous names have thrown their hat in the Micro Four Thirds ring, including Carl Zeiss, Cosina, Komamura, and Schneider Kreuznach, although of these only Cosina has yet to reach market with a 25mm f/0.95 prime. Korean optics manufacturer Samyang is expected to begin shipping a 7.5mm f/3.5 fisheye from September 2011. A new startup company called Noktor has also shipped a completely manual 50mm (100mm equivalent) F0.95 prime lens, manufactured by Goyo Optical, which appears to be based on a design intended for CCTV security cameras. Finally, several low-cost, lomo-type and even pinhole lenses are available from lesser-known companies such as SLR Magic and Wanderlust.
The Micro Four Thirds mount has an unusually small flange to sensor distance, which means there's plenty of room to insert mount adapters between the camera body and lens flange. As a result, a vast selection of adapters make it possible to mount all sorts of current and historic glass on a Micro Four Thirds camera. Lenses that can be adapted include certain standard Four Thirds, Olympus OM, Canon FD, Nikon F, Pentax K, Sony / Minolta Alpha, Contax / Yashica, M42, T2, Leica M / R, Voigtlander VM / Ai-S / PK-A/R / KA, and Carl Zeiss ZM / ZF / ZK types. These adapters generally have some limitations as to compatibility and available features, which will depend on the specific model being used, but photographers on the Micro Four Thirds platform can rest assured they won't be left wanting in terms of compatibility with other lens mounts.
Because the company's lenses largely feature optical stabilization, the Panasonic G3 doesn't itself incorporate in-body image stabilization. This means that while third party lenses can be used with the camera, only Panasonic's lenses offer stabilization on the G3 (at least, for the time being -- it's certainly possible that a third party could offer its own stabilized Micro Four Thirds lens in the future).
Panasonic G3 Autofocus
The Panasonic G3 has a 23-area contrast-detect autofocus system, using the main imaging sensor to determine focus, similar to how most point & shoot cameras work. There are five AF Area options, selected by pressing the Left arrow key on the four-way controller, which doubles as an AF Mode button. These options include Face Detection, AF Tracking, 23-area Focusing, 1-area Focusing, and Pinpoint. In addition, there are three focus servo modes, selected with the Focus Mode option on page two of the Record menu. These are Single AF (AFS), Continuous AF (AFC), and Manual.
A built-in AF Assist lamp illuminates the center of the image frame in difficult lighting conditions, to assist in achieving a focus lock. Its effective range varies depending on the lens in use, and it can be disabled altogether for situations when it might prove a distraction to your subject, or otherwise objectionable. Lenses with larger diameters may partially or completely block the assist lamp from illuminating your subject.
When the AF Mode is set to Face Detection, the camera automatically detects up to 15 faces in a scene, and can be programmed to recognize six specific individuals whenever they appear in the frame, allowing them to be prioritized over other faces when recognized. (In other words, you can train the camera to distinguish six specific people from others, and base exposure and focus on just their faces, rather than others in the frame.) The G3 will focus on an individual selected by the face recognition function if possible, or on the dominant face if no individuals are recognized. When a photo contains more than one recognized face, the camera selects on which face to focus based on the priority selected when programming the faces to be recognized. There's also a three-step control over the facial recognition sensitivity, allowing higher recognition accuracy (but with an increased likelihood that one of the designated faces won't be recognized), or vice versa.
The face selected for focusing is indicated by a yellow frame until focus lock is achieved, at which point the frame color changes to green; other faces get a white frame to indicate their location. Once detected, faces are tracked around the screen automatically. A manual AF point can be set in face detection mode by simply touching the desired point on the screen, and one of four point sizes selected by dragging a slider that appears at the right-hand side. The point position can also be set or adjusted with the arrow buttons on the back of the camera, and the size adjusted by rolling the rear dial. If a manual point is set, all detected faces are still indicated with white frames, but not used for AF calculation.
The AF Tracking mode is great for shooting sports, kids, and pets, as it automatically tracks any moving subject -- not just faces -- around the frame, based on the subject's tone and color. The subject can be selected by touching it on the screen. Alternatively, it can be selected by aiming the camera so as to place the AF point over the subject, then half-pressing the shutter button. The tracking function will relocate a subject if it briefly leaves the frame, even if it doesn't reenter from the same direction. When tracking, the subject is indicated with a yellow frame. Face recognition is disabled when the camera is set to AF tracking mode. The tracking mode also doesn't function when the Panasonic G3 is set to the Monochrome photo style, or when the Creative Control mode is set to Sepia.
In 23-Area Focusing mode, the G3 defaults to automatically selecting between all twenty three focusing points. By touching the screen, one of nine groups of AF points can be selected, and the camera will automatically choose only from the points in the selected group. Each group consists of five points, apart from in the extreme corners of the frame, where the groups only contain four points. The selected group is indicated by a cross mark in the center of the cluster of AF points.
The 1-Area Focusing mode provides a single autofocus point which can be moved anywhere within the frame except the extreme edges, again either by touching the display or by using the arrow buttons. As with the face detection mode, the AF frame size can be changed to Spot, Normal, Large or Extra Large, either by dragging an on-screen slider, or by rolling the rear dial. The pinpoint mode operates in a similar manner, except with an even smaller, fixed point size.
In Single AF servo mode, the camera will attempt to determine the point of focus when the shutter button is half-pressed, and then lock focus at this distance for as long as the shutter button remains pressed. Through the Custom menu, you can assign either the Disp./Fn1 or Q.Menu/Fn2 buttons (or both) to serve as either an autofocus lock button, an autoexposure lock button, or a combined AF/AE lock button, with a second press releasing the lock. A further Custom setting instructs the camera to operate in AF+MF mode, allowing the point of focus to be fine-tuned manually after the autofocus operation is complete.
In Continuous AF servo mode, the camera will attempt to predict subject motion and keep the area under the AF point in focus, for as long as the shutter button remains half-pressed. Because contrast-detect AF systems have to perturb the focus in order to tell whether the image is actually in focus or not, the DMC-G3's Continuous-AF mode's operation can be seen in the live view feed, at least if you're watching closely: The image will continuously shift very slightly in and out of focus when C-AF is active, as the camera constantly re-checks its focus setting.
A Focus Priority setting in the Custom menu allows the Panasonic G3 to be set to require a focus lock before the shutter can be triggered, or alternatively to allow the shutter to fire regardless of whether a lock has been achieved. When shooting in burst mode with continuous AF, enabling Focus Priority can reduce the burst speed, because a focus lock must be obtained before each shot in the burst. With Focus Priority disabled, the G3 simply focuses at the predicted distance for each subsequent image in the burst, without actually confirming a focus lock has been achieved. (For bursts in Single AF mode, focus is locked from the first shot, so the only effect enabling Focus Priority has in this situation is that it delays firing of the first frame in the burst, until a focus lock has been achieved.)
Through a Record menu setting, the Panasonic G3 can be configured to begin seeking a focus lock as soon as the camera is held relatively steady, before the shutter button is half-pressed. When this Quick AF setting is enabled, the time to obtain an AF lock should be reduced, but at the expense of battery life.
Of course, the Panasonic DMC-G3 also offers a Manual Focus mode. In MF mode, a Custom setting called MF Assist optionally causes the camera to magnify the preview image by 5x, whenever the focus ring is adjusted, to help determine critical focus. The MF assist preview can be panned around the image frame by dragging your finger across the surface of the display, and the zoom level increased to 10x (and reverted to 5x) by pressing an on-screen magnifying glass icon. After 10 seconds of manual focus inactivity, the Panasonic G3 reverts to showing the full image frame. Alternatively, a small window showing a 4x zoomed view can be shown at the center of the screen, while the remaining area shows the live view feed, helping you keep your framing unchanged during manual focus operation.
For use with old manual-focus lenses (which lack the communication that would tell the body when the focus ring was being adjusted), or perhaps to simply check the focus that the AF system has achieved, it's also possible to call up the MF assist function without first adjusting focus, by pressing the Left-arrow button when in MF mode. An MF Guide function displays an on-screen gauge with a visual indication of the current relative focus distance, making it easy to see whether you're focusing closer or further away when the focus ring is turned. (It doesn't display the actual focus distance, just a relative range from close-up to infinity.)
While the LCD on the Panasonic G3 has a reasonably high-resolution design, with some ~153,000 pixels (460,000 dots), the electronic viewfinder offers 480,000 pixel resolution, and so presents the best choice for manual focus operation, or confirmation of precise autofocus.
In the above discussion, we mentioned several times how the Panasonic G3's touch screen can be used to set the AF point, identify the desired subject, or call up the focus-assist display in Manual Focus mode. We've often said that we're no particular fans of touch-screen interfaces, but the touch interface on the previous Panasonic G2 model really made believers of us, and the G3 retains that heritage. Shawn and Dave first heard about the original G2's touch interface in the non-disclosure briefing, and shared much the same initial opinion: "eh - another gimmicky touch-screen interface." Once they had a chance to shoot with the camera, they found their opinion changing pretty radically. The touch interface on the G2 and G3 is really done exactly right, and using it to set focus or select a subject for tracking is an incredibly natural way of doing so. Perhaps the best measure of how much we all like it is how often we find ourselves wanting to select an AF point on other cameras we're testing by poking their screens.
Shawn made a video showing how the Panasonic G2's touch interface works for our review of that camera, and with the touch interface being a similarly integral part of the G3 experience, we think it's worth re-linking here. Check it out, it's really a very intuitive way of relating to your camera!
AF in Movie mode
In Movie mode, you have the same focusing options available as when shooting stills, and it is possible to adjust focus not only before movie recording starts, but also during recording. There
are a couple of differences from their still image counterparts though -- the most
obvious being the absence of the beep that serves to confirm AF lock. Also, when set to AF-C servo mode, the Panasonic G3 looks to a setting in the Motion Picture menu to determine whether to allow Continuous AF. If the option is disabled, the G3 will operate in Single AF mode, regardless of the Focus Mode being set to AF-C, performing an AF operation only until a lock is achieved. If the option is enabled, Continuous AF becomes available during movie recording as well as for still images. Since focus operation is picked up by the camera's internal
microphone, you may want to choose either S-AF or MF modes to minimize the presence of AF drive noise. It's also important to note that even when in MF mode, focus operation can result in motor noise being picked up on the audio track, since most Micro Four Thirds lenses use a fly-by-wire system for manual focusing, rather than a direct mechanical linkage. The extent to which AF noise is recorded on the audio track will vary depending on the specific lens used, and Panasonic's own HD-branded lenses offer much quieter AF operation than is typical.
Panasonic DMC-G3 Sensor Cleaning
The Panasonic DMC-G3 features an ultrasonic dust-reduction system, especially important since the DMC-G3's shutter is normally open for full-time Live View. The system automatically runs at power-up, and might as a result slow camera startup slightly. We measured the G3's delay from power-on to first shot at about 1.4 seconds. Not only is that slower than some competing SLR models, but it's also around 0.4 seconds slower than the previous Panasonic G2 model. That said, the G3 still starts up quickly enough that we didn't feel it would be likely to cause us to miss a shot.
We have found, however, that in-camera dust-removal systems are less than perfectly effective. You're still going to need to use a sensor-cleaning kit fairly often, so the advantage of in-body dust removal is perhaps less than it might seem. If you've got dust specks on your sensor (and sooner or later you will), you're going to need to clean it. There are a lot of products out there intended to address this need, but a distressing number of them work poorly (if at all), and many are grossly overpriced. Advertising hype is rampant, with bogus pseudo-scientific jargon and absurd product claims. And prices -- Did I mention prices? How about $100 for a simple synthetic-bristle brush?
So how do you know what product to use?
We don't pretend to have used everything currently on the market, but we can tell you about one solution that worked very well for us. The "Copper Hill" cleaning method is straightforward and safe, and in our routine usage here at Imaging Resource, highly effective. Better yet, the products sold by Copper Hill Imaging are very reasonably priced. Best of all, Nicholas R (proprietor of Copper Hill) has put together an amazingly detailed tutorial on sensor cleaning, free for all.
Sensor cleaning is one of the last things people think about when buying a d-SLR, but it's vital to capturing the best possible images. Take our advice and order a cleaning kit from Copper Hill right along with your d-SLR, so you'll have it close at hand when you need it: You'll be glad you did!
(While they've advertised on our sister site SLRgear.com from time to time, we receive no promotional consideration from Copper Hill for this note. We just think their sensor cleaning products are among the best on the market, and like their way of doing business. -- We think you will too. Click here to check them out.)
Kit Lens Test Results
Fair to good performance with the 14-42mm O.I.S. (Optical Image Stabilized) kit lens.
The Panasonic G3 is available bundled with a Lumix G Vario 14-42mm f/3.5-5.6 MEGA O.I.S. Micro Four Thirds lens. This kit lens possesses a typical optical zoom ratio of 3x, and has a 35mm equivalent focal range of about 28-82mm, because of the G3's 2x "crop factor". Results were pretty good at 14mm and f/8, with only minor softness in the extreme corners and fairly strong detail throughout the rest of the frame. Coma distortion in the trees in the corners was low to moderate, and chromatic aberration very low with much of it processed out. Performance at 25mm (50mm eq.) and f/8 was also good, though corners were still slightly soft, with the top-left softer than the others. Chromatic aberration was negligible. Sharpness was good across much of the frame at 42mm at f/8, though the top-left corner was quite soft, with some slight blurring and coma distortion in the other corners. Again very little chromatic aberration was visible. Overall, a fair to good performance for an inexpensive kit lens, and the optical image stabilization should help handheld shots in poor light.
A larger-than-average area, with good but slightly soft detail. Flash throttles down well.
|Macro with 14-42mm kit lens
|Macro with Flash
As with zoom performance, the Panasonic G3's macro performance will depend entirely on the lens in use. However, with the 14-42mm kit lens set to 42mm, the Panasonic G3 captured a larger-than-average minimum area measuring 3.92 x 2.94 inches (100 x 75 millimeters). Detail was quite good but a bit soft, with a touch of additional softening in the extreme corners. (Most lenses have some softening in the corners at macro distances, the Panasonic G3's kit lens has less than most.) Some minor light fall-off ("vignetting") is also noticeable in extreme corners. The Panasonic G3'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 good exposure with the flash.
Low geometric distortion with the 14-42mm kit lens in JPEGs; high barrel distortion at wide-angle in uncorrected RAW files.
|In-Camera JPEG: Barrel distortion at 14mm is about 0.3 percent|
|In-Camera JPEG: Pincushion distortion at 42mm is 0.3 percent|
|Uncorrected RAW: Barrel distortion at 14mm is 2.0 percent|
|Uncorrected RAW: Pincushion distortion at 42mm is 0.3 percent|
When shooting JPEGs, the Panasonic G3's 14-42mm kit lens produced about 0.3 percent barrel distortion at wide-angle, which is much less than that produced by most kit lenses we've tested, and hardly noticeable in images. At the telephoto end, there was about 0.3 percent of pincushion distortion which is a little higher than average, but also not very noticeable. 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 G3 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 presumably other raw converters that support the G3's RW2 files) applies distortion correction automatically, so results are very similar to in-camera JPEGs. As you can see, at wide-angle barrel distortion is very high at about 2.0 percent, however pincushion distortion at telephoto remained roughly the same as the in-camera JPEGs, at 0.3%. (The high barrel distortion at wide-angle is not unusual for a Micro Four Thirds lens, but the extent of distortion correction required may explain some of the softness we saw in the corners at short focal lengths.)
Chromatic Aberration and Corner Sharpness
Very low to moderate chromatic aberration when shooting JPEGs with the 14-42mm 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 G3's 14-42mm kit lens was very low to moderate at the 14mm setting, with fairly dull mostly purple/blue fringing in the corners. At 42mm telephoto, this distortion was lower and even 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 G3's 14-42mm kit lens produced some soft corners. At full wide-angle, three corners were moderately soft with the upper-left arguably the softest, while the bottom right was sharper. Blurring extended quite a ways into the frame, though the center was very sharp. At full telephoto, corner sharpness was similar with the same three corners moderately soft and the bottom right reasonably sharp, but the center was also slightly soft, and suffers from lower contrast than at full wide-angle. Some light fall-off in the corners ("vignetting") was also noticeable at the wide-angle end.
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.
|Wide: Camera JPEG||Wide: Uncorrected RAW|
|Tele: Camera JPEG||Tele: Uncorrected RAW|
Chromatic Aberration Correction. We weren't surprised to find the G3 reduces chromatic aberration during JPEG processing (good for JPEG shooters), as most Panasonic point & shoot and G-series models do. Above are crops comparing camera JPEGs to uncorrected RAW files converted with dcraw. Chromatic aberration is more obvious and slightly different at wide-angle (green and purple) and telephoto (cyan and red) than in the corrected JPEGs, though it's still fairly well controlled. (As mentioned above, SilkyPix performs 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.)