Panasonic LX10 Optics

Zoom
A very fast, 3x wide-angle zoom with good far-field performance.

The Panasonic LX10 is equipped with a 8.8-26.4mm lens, offering an optical zoom ratio of 3x, translating to a 35mm-equivalent focal range of about 24-72mm. That's a fairly limited range for a fixed-lens camera but actually a bit longer than a close rival, the Sony RX100 IV or V at 70mm. The lens is very fast (bright), with a maximum aperture ranging from f/1.4 at wide angle to f/2.8 at telephoto. That's 2/3rds of a stop faster than the Sonys at the wide end and the same at telephoto. The following table reflects the maximum and minimum apertures as reported by the LX10:

At maximum wide angle, sharpness and contrast are quite good across the frame at f/5.6, though there's some slight softening and coma distortion in the corners. Chromatic aberration is well-controlled though some flare can be see around very bright objects. Performance at medium focal length (50mm eq.) is commendable with very good sharpness and contrast across the frame at f/5.6. Far-field performance at full telephoto also appears to be quite good at f/5.6 across the frame.

The Panasonic LX10 also offers up to 4x digital zoom at full image size, though it suffers from the usual loss in image quality at that magnification due to interpolation artifacts and more visible noise. The LX10 also offers a 2x iZoom mode with better image quality than 4x, as well as Extended Optical Zoom which just crops the image when Medium or Small Picture Size is selected for a maximum of 6x total "optical zoom" at 5 megapixels.

It's difficult to judge lens performance using such a deep and high-contrast scene (this series is meant mainly to convey zoom range), so see below for lab results on corner versus center sharpness, geometric distortion, chromatic aberration, macro performance, etc.

Macro
A slightly smaller than average minimum coverage area, with very good performance. Flash throttled down well at minimum focus.

The Panasonic LX10's macro mode captured a slightly smaller than average sized minimum area measuring 2.12 x 1.41 inches (54 x 36 millimeters), which is quite good, especially compared to competing 1-inch sensor models. Sharpness over much of the frame is good, however extreme corners show some minor blurring even at f/8 (most lenses show some softening in the corners at macro distances, so this is typical). Exposure with the flash was not too bad for such a close distance, though exposure was uneven because of the location of the flash relative to the lens, overexposing the top left and underexposing the bottom right of the frame.

Geometric Distortion
Very low distortion in camera JPEGs, but very high in uncorrected RAW files at wide angle.

Thanks to in-camera distortion correction, there's low geometric distortion in the LX10's JPEG files at wide angle. At full wide angle, we measured just under 0.3% barrel distortion which is pretty low but still visible. At full telephoto, distortion is very low at just over 0.1% barrel distortion, instead of the usual pincushion we normally see at telephoto. 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).

To see how much correction is taking place in the camera, we converted RAW files from the above shots with dcraw which ignores embedded lens correction profiles. As you can see at wide angle, barrel distortion is very high at about 3.6%, while telephoto shows about 0.4% of barrel distortion.

We expect to see fairly significant distortion in uncorrected RAW files in fast, compact lenses, as allowing this gives the lens designers greater flexibility in optimizing center sharpness as well as in reducing cost, size, and weight. The downside is that the distortion correction contributes to additional blurring in the corners of the frame where pixels are "stretched" during correction and where lenses are usually already a bit soft. Note that RAW converters that officially support the LX10's RW2 files will apply distortion corrections automatically, as specified by Panasonic in the lens profile built into the RAW files.

Chromatic Aberration and Corner Sharpness
Moderate to very low chromatic aberration in JPEGs. The lens produces some slightly soft corners at both wide angle and telephoto ends when wide open.

Chromatic Aberration. The LX10's lens exhibits moderate lateral CA in the corners wide open at wide angle, and moderately low lateral CA in the corners wide open at telephoto in JPEGs. However, there are clear signs that CA is being suppressed, especially at telephoto where you can see soft and desaturated edges. As expected, uncorrected RAW files (see below) show much more CA than seen above.

Corner Softness. Wide open at full wide angle, the LX10's lens is very sharp in the center, but all four corners are somewhat soft, with some softness extending deep into the frame. Much of the softness is due to the strong distortion correction, and you can also notice some interpolation artifacts in the form of rough edges in the USAF target. Still, a very good performance for the aperture and focal length. Wide open at full telephoto, corners are slightly soft and exhibit a loss of contrast and the aforementioned desaturated edges. The center shows good sharpness wide open, but is not quite as sharp as wide angle.

Vignetting. There's some vignetting (corner shading), with a little more at wide angle than at full telephoto, though it's fairly minor.

F5.6: At max wide angle, corner sharpness and chromatic aberration didn't improve much when stopped down to f/5.6, remaining somewhat soft, though contrast is a bit better. This isn't a surprise given the amount of correction applied, though. Sharpness in the center did however degrade slightly when stopped down, due to diffraction (a shot at f/4 showed minor improvement over wide open). At full telephoto, corners improved quite a bit, becoming almost as sharp as the center with much better contrast and without the desaturated edges. Sharpness in the center improved slightly over wide open, and vignetting was not detectable at either end.

Chromatic Aberration Correction

As you can see in the crops from uncorrected RAW images on the right (taken from RW2 files converted with dcraw), the LX10's lens produces high and very bright lateral chromatic aberration at wide angle, and what we'd call moderately high CA at full telephoto. So the LX10's processor does a great job suppressing lateral chromatic aberration in camera JPEGs (crops on the left). Note that most RAW converters should also automatically suppress CA when converting the LX10's RW2 files, in addition to correcting geometric distortion.

Overall, pretty good performance from the LX10's lens considering its size, speed and the camera's price.

Coverage
Excellent accuracy from the LCD monitor.

The Panasonic LX10's LCD monitor provided just under 100% coverage at wide angle and just over 99% at full telephoto in our tests. This is excellent performance, especially considering the amount of geometric distortion correction taking place at wide angle.