Panasonic LX7 Optics

Zoom

Excellent performance from the 24-90mm equivalent lens.

The Panasonic LX7 is equipped with a 4.7-17.7mm lens, offering a somewhat limited optical zoom ratio of about 3.8x for a compact, with a 35mm equivalent focal range of about 24-90mm. The beauty of this lens is its speed (brightness), offering a very fast f/1.4-2.3 maximum aperture which is excellent for low-light and also provides reduced depth-of-field for better subject isolation. The following table reflects the minimum and maximum apertures versus focal length as reported by the camera:

Far-field lens performance in general is excellent at f/5.6 and wide-angle, medium and telephoto, with very good sharpness and contrast across the frame, low chromatic aberration (the LX7 suppresses it), and good resistance to flare. The LX7 also offers up to 4x digital zoom, though with the usual loss of detail and visible noise that high digital magnification produces.

Overall, this is an excellent lens. It's also fast (bright) and optically stabilized, making it great for low-light shooting as well. See below for comments on macro performance, geometric distortion, corner softness, etc.

Macro
A very small minimum coverage area, with very good detail. Flash is almost completely blocked at minimum distance.

The Panasonic LX7 captures a very small minimum area measuring 1.13 x 0.85 inches (29 x 22 millimeters) in macro mode. Detail is very good in the center, though corners show moderate softening (most lenses show some softening in the corners at macro distances). The flash seems to throttle down well, but is almost completely blocked by the lens at minimum distance, producing a mostly black image. You'll want to use external lighting for the closest LX7 macro shots.

Geometric Distortion
Higher than average barrel distortion at wide-angle in JPEGs, much higher in uncorrected raw files. Very low distortion at telephoto.

Panasonic LX7 JPEG images show about 0.9% barrel distortion at wide-angle which is a little higher than most and noticeable in some images, but less than 0.1% complex (wavy) pincushion distortion at full telephoto, which is very low. 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 of the above shots with DxO Optics Pro 7 with corrections disabled. As you can see, at wide-angle, barrel distortion is extremely high at about 4%, while distortion at telephoto is essentially unchanged at less than 0.1%.

It's not at all unusual these days to see fairly significant distortion in uncorrected raw files, so it's nothing to be concerned about unless you are using a raw converter which does not understand the embedded "opcodes" to perform distortion corrections automatically. Most raw converters these days (including Adobe Camera Raw and SilkyPix) are capable of applying distortion correction automatically, as specified by the manufacturer. There is however going to be some loss of resolution in the corners as a result of such correction, because pixels in the corners of the frame are being "stretched" to correct for the distortion. Obviously, a lens that doesn't require such correction, and is also sharp in the corners to begin with would be preferable, but relaxing constraints on distortion brings other benefits in the lens design, such as a very compact design.

Chromatic Aberration and Corner Sharpness
Low to moderate chromatic aberration at wide-angle; moderately low levels at full telephoto. Corner sharpness is quite good even wide-open, which is remarkable for such a fast wide-angle lens.

Chromatic Aberration. Thanks to in-camera chromatic aberration suppression, there are very low (center) to moderate (corners) levels of chromatic aberration from the LX7's lens at wide-angle when wide-open. At wide-open full telephoto, chromatic aberration is moderately low, though you can see some lateral or transverse C.A. even in the center if you look closely, however it's quite dim. See below for C.A. in uncorrected raw files.

Corner Softness. Wide-open at full wide-angle, the lens shows only slight blurring in the corners, which is quite remarkable given the speed of the lens as well as the extreme distortion correction taking place. (Much of the softness is due to the "pixel stretching" required to reduce distortion, and you can see some artifacts such as jagged edges along horizontal and vertical lines as well.) The center at wide-angle is quite sharp. At full telephoto, corner sharpness is a little better than at wide-angle with no distortion correcting artifacts, though still a touch soft, while the center remains quite sharp. Excellent performance.

Vignetting. There's no vignetting (corner shading) to be seen which is unusual for such as fast lens, likely corrected during processing.

Stopping down to f/5.6 improves corner sharpness at both wide-angle and telephoto, though they still aren't quite as sharp as the center, while also reducing chromatic aberration. Vignetting is again not an issue.

Chromatic Aberration Correction
Much higher levels of C.A. at wide-angle and telephoto in uncorrected raw files.

As you can see from crops above comparing camera JPEGs on the left to raw files converted with DxO Optics Pro 7 with corrections disabled on the right, levels of chromatic aberration are much higher in uncorrected raw files, particularly at wide-angle.

Coverage
Excellent accuracy from the LCD monitor.

The Panasonic LX7's LCD monitor shows essentially 100% coverage at full wide-angle and telephoto. This is excellent performance, especially considering the amount of geometric distortion correction taking place at wide-angle.