Panasonic LX100 Optics

Zoom
A shorter than average wide-angle zoom, with good far-field performance.

The Panasonic LX100 is equipped with a 10.9-34mm lens, offering an optical zoom ratio of 3.1x, translating to a 35mm-equivalent focal range of about 24-75mm. That's a fairly limited range for a fixed-lens camera, especially one that doesn't offer a ton of resolution to crop from. But the lens is very fast (bright), with a maximum aperture ranging from f/1.7 at wide angle to f/2.8 at telephoto, which is excellent for low-light shooting and facilitates reduced depth-of-field for better subject isolation. The following table reflects the maximum and minimum apertures as reported by the camera at popular focal lengths:

At maximum wide angle, sharpness and contrast are quite good in the center of the frame at f/8, though there's some softening and coma distortion in the corners. Chromatic aberration is very low, as like most cameras, the LX100 suppresses it. Some flare can be see around very bright objects, though, but it appears to be fairly well-controlled. Performance at medium focal length (50mm eq.) is commendable with very good sharpness and contrast across the frame. Far-field performance at full telephoto appears to be good at f/8 across most of the frame, though it's not quite as sharp in the center as at shorter focal lengths. Note that the above images were taken at a 3:2 aspect ratio.

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

Macro
A slightly smaller than average minimum coverage area, with very good detail in the center. Flash worked well at minimum focus.

The Panasonic LX100's macro mode captured a slightly smaller than average sized minimum area measuring 2.23 x 1.68 inches (57 x 43 millimeters), which is quite good, especially compared to competing 1-inch sensor models. Sharpness in the center is very good, but corners show strong blurring even at f/8 (most lenses show some softening in the corners at macro distances, so this is typical). Exposure with the bundled flash was surprisingly good at such a close distance (a little over an inch or about 3 cm from the front of the lens). Nice.

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 LX100's JPEG files at wide angle. At full wide angle, we measured just under 0.4% barrel distortion which is pretty low but still visible. At full telephoto, distortion is very low at just under 0.2% pincushion distortion. 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 RawDigger, which does not correct for distortion (and also doesn't do full demosaicing, so please do not evaluate image quality using these uncorrected images). As you can see at wide angle, barrel distortion is very high at about 3.4%, while telephoto shows about the same very low pincushion distortion as JPEGs.

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 and other aberrations, as well as in reducing cost, size, and weight. The downside is that the distortion correction contributes additional blurring to 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 LX100'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
Moderately low to very low chromatic aberration in JPEGs. The lens produces some slightly soft corners at both wide angle and telephoto ends.

Chromatic Aberration. Thanks to in-camera chromatic aberration suppression, there's low CA in the corners at wide angle, and moderately low CA in the corners at telephoto in JPEGs. As expected, though, uncorrected RAW files (see below) show much more CA than seen above.

Corner Softness. Wide open at full wide angle, the LX100's lens is sharp in the center, but all four corners are slightly soft, with some softness extending perhaps a third of the way 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, pretty good performance for the aperture and focal length. Wide open at full telephoto, corners are also somewhat soft with the top left the softest, however the softness does not extend nearly as far into the frame and the center exhibits good sharpness.

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

F8: At max wide angle, corner sharpness didn't really improve much if at all when stopped down to f/8, remaining somewhat soft, though contrast is better. This isn't a surprise given the amount of correction applied, though. Sharpness in the center did however improve slightly when stopped down. At full telephoto, the upper corners improved but they're still not tack sharp, while lower corners actually became a touch softer, which is a little disappointing. Sharpness in the center remained about the same, 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 RawDigger), the LX100's lens produces moderately high and bright lateral chromatic aberration at wide angle, and what we'd call moderate CA at full telephoto. So the LX100'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 LX100's RW2 files, in addition to correcting geometric distortion.

Overall, good performance from the LX100's lens considering its size, speed and the camera's price, but it's a little short on reach compared to some competing cameras, and corner performance is somewhat disappointing, at least at the wide and tele ends.

Coverage
Excellent accuracy from the electronic viewfinder and LCD monitor.

The Panasonic LX100's EVF and LCD monitor both provide essentially 100% coverage at wide angle and telephoto in record mode. This is excellent performance, especially considering the amount of geometric distortion correction taking place at wide angle.