Sony A7 Optics

Zoom
Limited zoom range, with decent if not stellar performance for a full-frame kit lens.

The Sony A7 is available bundled with a 28-70mm f/3.5-5.6 OSS "kit" lens. This optically stabilized lens possesses a lower than average optical zoom ratio of only 2.5x, and because the A7 is a full-frame camera, there is no crop factor.

Sharpness and contrast at full wide angle (28mm) are very good at f/8 in the center, though corners and edges show some significant softness, particularly on the left side of this sample. Chromatic aberration isn't an issue since the camera suppresses it (see below), and flare seems well controlled. At full telephoto (70mm) and f/8, the lens also performs fairly well with good sharpness across much of the frame, though corners and edges still exhibit some noticeable softness.

(Note: We had to return our original kit lens before testing was completed, so the shots taken above were from a different copy of the lens than the lab shots below. There are unfortunately noticeable differences in optical performance, so please be aware that there can be significant sample variation.)

Digital Zoom
The A7 offers three types of digital zoom. Sony's "Clear Image" digital zoom is available at 2x magnification, standard digital zoom up to 4x, and "Smart Zoom" is available where the camera just crops away the unused portion of the image when a lower resolution is selected. You can combine the various digital zooms as well, but maximum total digital zoom is 4x at full resolution.

Clear Image zoom appears to do a pretty good job at 2x magnification. Standard 4x digital zoom shows the typical loss of detail that amount of enlargement produces. It's difficult to tell given the lack of fine detail in this scene at these zoom levels, but it's probably best to avoid using standard digital zoom and instead crop, upsize and sharpen as required during post processing.

Macro
A much larger than average minimum coverage area, with good detail.

As with zoom performance, the Sony A7's macro performance will depend entirely on the lens mounted. However with the 28-70mm kit lens set to 70mm, the A7 captures a minimum area measuring 6.26 x 4.17 inches (159 x 106 millimeters), which is much larger than average for a kit lens. Sharpness is very good across most of the frame at f/8, with corners that are just a touch soft, particularly on the right side. (Most lenses have some softening in the corners at macro distances.)

Geometric Distortion
Lower than average geometric distortion at wide angle and telephoto in JPEGs, but the A7 always applies distortion correction to JPEGs when the 28-70mm kit lens is mounted.

With the 28-70mm kit lens, the Sony A7 produces JPEGs with about 0.2 barrel distortion at both maximum wide angle (28mm) and full telephoto (70mm). In both cases, distortion is quite low and hardly 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).

See below for uncorrected distortion from this lens.

Chromatic Aberration, Corner Sharpness & Vignetting
Low levels of C.A. (and the A7 suppresses it). The lens produces some soft corners.

Chromatic Aberration. Chromatic aberration in the corners at wide angle (28mm) while wide open is moderately low with some minor magenta fringing, and the center of the image shows very little C.A. The camera does a pretty good job at suppressing much of the lateral C.A. produced by the lens (see below). At full telephoto (70mm), C.A. is is quite low and muted across the frame.

Corner Softness. Wide open at full wide angle, the 28-70mm lens that first came with our A7 is just a touch soft in all four corners, and the center is quite sharp with excellent contrast. Wide open at full telephoto, corners on the right-hand-side are soft and exhibit some astigmatism with better vertical resolution than horizontal. Blurring extends deep into the frame from the right side, while the left side is fairly sharp, and the center is sharp.

Vignetting. Minor vignetting (corner shading) is noticeable at full wide angle and telephoto, as indicated by the darker corner crops, even with automatic vignetting correction enabled by default (see below).

F/8: "Stopped-down" to f/8, corner sharpness improved at wide angle to the point where they are almost as sharp as the center. Excellent performance here. At full telephoto, corner sharpness improved in the top right, but the bottom right corner actually became a little softer. Minor to moderate vignetting is still visible at f/8 at both ends of the zoom, and C.A. remains well controlled.

Overall, decent performance for a full-frame kit zoom lens, especially considering its low price (~US$300) when purchased bundled with the camera. Our second copy however didn't seem to perform as well (at least in our far-field shots), so be aware of significant sample variation.

Lens Corrections

The Sony A7 has the ability to automatically compensate for geometric distortion, chromatic aberration, and lens shading (vignetting), as images are captured. Only E-mount lenses are supported.

Geometric Distortion

Above, you can see the uncorrected geometric distortion from the 28-70mm kit lens is moderately high at wide angle, with about 0.9% barrel distortion. At the telephoto end, pincushion distortion is higher at about 1.3%.

The default Distortion Compensation setting is normally Off for the A7, but is forced to Auto when some lenses such as the 28-70mm lens are mounted. In cases where distortion correction can't be disabled on the camera, we use RawDigger or dcraw to convert RAW files as they both don't apply distortion correction even if a RAW file contains correction instructions. Thus, like most Micro Four Thirds lenses, it appears that Sony designed this lens with considerable geometric distortion and is correcting it during processing.

Chromatic Aberration

Above, you can see significantly higher lateral Chromatic Aberration in the corners at wide angle with Chromatic Aberration Compensation disabled, though the difference at telephoto is minimal because C.A. is low at full telephoto to begin with. The default for this setting is Auto.

Shading (Vignetting)

Mouse-over the links above to see the difference the A7's Shading Compensation makes when wide open (the worst-case scenario for most lenses). As you can see, significant corner shading correction is being performed particularly at wide angle, though some fall-off is still left behind at both ends of the zoom in the corrected images. The default for this setting is also Auto.

Note that the Sony A7 applies Shading Compensation to RAW (ARW) files as well as JPEGs, so if you'd rather correct for it yourself when shooting RAW, make sure to turn Shading Compensation off before shooting. As far as we can tell, Shading Compensation is the only lens correction the A7 bakes into RAW image data (the other corrections are just tags in metadata).

Coverage
Excellent accuracy from the EVF and LCD monitor.

The Sony A7's OLED electronic viewfinder and LCD monitor both show just over 100% coverage with our FE 55mm f/1.8 prime lens. Excellent performance.