Sony NEX-C3 Optics
Sony NEX-C3 Optics
The Sony NEX-C3 is available bundled with either an 18-55mm f/3.5-5.6 zoom lens, or a 16mm f/2.8 prime. The zoom lens offers 35mm-equivalent focal lengths from 27 to 83mm, while the prime is a 24mm equivalent.
With the 18-55mm zoom lens mounted, the NEX-C3 is rather too bulky to be considered pocketable, although it's still a fair bit smaller than the typical consumer SLR with a similar lens. Sharpness is about average, while autofocus is fairly quick, quiet and well-suited to movie capture, and the Optical SteadyShot image stabilization proves useful, especially towards the telephoto end of the zoom range. In the in-depth tests performed at our sister site, SLRgear, we did find some issues with chromatic aberration towards the middle of the zoom range, as well as distortion at most focal lengths, however. More details can be found in our SLRgear.com review.
As for the 16mm prime lens, it offers an interesting proposition as a walkaround lens, making the NEX-C3 just about pocketable without first removing the lens. In testing at SLRgear, we did note high levels of chromatic aberration, as well as prominent distortion and rather soft results, especially at maximum aperture. Many consumers may well be willing to overlook these shortcomings given the lens' affordability and compact size, however.
Although it's still a fairly young system, there's quite a healthy selection of glass available for E-mount cameras. As of this writing (October, 2011), Sony offers seven E-mount lenses: three zooms that together cover a range from 18-210mm (27-315mm equivalents), and four primes from 16mm to 50mm (24mm to 75mm equivalents.) For the zoom lenses, all are stabilized. Among the primes, only the 50mm lens offers stabilization. There's also one lens carrying Carl Zeiss branding, the Sonnar 24mm f/1.8, which is tied with the 50mm prime as brightest first-party lens available for the E-mount.
In full, the list of E-mount lenses available from Sony is as follows:
|Sony E-mount lenses|
Sony E 18-55mm f/3.5-5.6 OSS (27-83mm equivalent)*
Sony E 18-200mm f/3.5-6.3 OSS (27-300mm equivalent)
Sony E 55-210mm f/4.5-6.3 OSS (83-315mm equivalent)
Sony E 16mm f/2.8 (24mm equivalent)*
Carl Zeiss Sonnar T* ZA 24mm f/1.8 (36mm equivalent)
Sony E 30mm f/3.5 (45mm equivalent)
Sony E 50mm f/1.8 OSS (75mm equivalent)
* available as a kit lens
In addition, two conversion lenses which can be mounted on the front of the 16mm prime increase the wide-angle possibilities for E-mount photographers still further, to either 15mm or 18mm equivalents. It's also possible to use Alpha-mount lenses (including older glass from Minolta and Konica-Minolta) with the NEX-C3, using either the LA-EA1 or LA-EA2 mount adapters.
Beyond the optics and adapters provided by Sony themselves, a wide variety of third-party options are also available. Sony has been uncommonly open with its E-mount, providing basic specifications to lens and mount adapter manufacturers without fee, and while that hasn't yet resulted in a flurry of third-party lenses, there are a vast array of mount adapters available that allow use of lenses from most common mounts. If you have a lens from a mount that's at least reasonably well-known, chances are an adapter will be available; there are so many that it's really beyond the scope of this review to attempt to cover them all. Suffice to say that there will be limitations in their use, however -- most notably with the lack of autofocus, and with vignetting on lenses designed to provide an image circle smaller than the NEX-C3's APS-C sized image sensor.
Third party lenses, at this time, are all completely manual, and include an 8mm fisheye from Korea's Samyang Optics, plus three primes (28mm f/2.8, 35mm f/1.7, and 50mm f/0.95) from Hong Kong's SLR Magic / Noktor. Japan's Sigma Corp. showed prototype lenses for the E-mount in early 2011, but has yet to release any products. A number of other manufacturers have expressed interest, but likewise have yet to release any E-mount lenses.
There are two approaches to mechanical image stabilization in compact system cameras: lens-based, or in-body (sensor shift). For the NEX series models, including the C3, Sony has opted for a lens-based system, branded as "Optical SteadyShot". One of the main advantages of lens-based stabilization in SLRs--the fact that the optical viewfinder image is also stabilized--doesn't apply in compact system cameras, since they're always operating in live-view mode, thus allowing sensor shift systems likewise to provide a stabilized preview. Still, lens-based stabilization typically performs better at longer focal lengths than do sensor-shift systems. There is a drawback, though: with a lens-based system, you must decide whether to opt for a stabilized version of each lens, and pay a premium for the stabilization, where in-body systems offer stabilization with pretty-much any lens.
Of the two available kit lens choices, only the 18-55mm zoom is stabilized, as are all currently-available E-mount zoom lenses from Sony. With the exception of the 50mm f/1.8, none of the current primes are stabilized. When using Alpha-mount lenses with the optional mount adaptors, stabilization is not available, since Sony's Alpha-series image stabilization relies on sensor shift ("SteadyShot Inside") technology inside the camera body, something that's not available in NEX-series bodies.
Like any compact system camera, the NEX-C3's lack of a mirror box means that there's nowhere in the optical path to put a dedicated phase detection sensor. Instead, the NEX-series cameras are reliant on the image sensor itself for autofocus. This means using contrast detection autofocus, by default, as do all mirrorless models except Nikon's J1 and V1. (Those cameras don't have a dedicated phase detect sensor, but include phase detection AF points on the main imaging sensor.) Sony's E-mount lenses were designed from the ground up with contrast detection autofocus performance in mind, with the weight and positioning of the focusing group tuned appropriately, and focus drive is provided by a near-silent stepper motor. This, along with the increased processing power of modern cameras, means that contrast detection autofocus is a much more useful proposition than was the case a couple of years ago, although it's typically still somewhat slower than phase detection. The advantage of contrast detection, though, is that it negates problems with front or back focusing, and generally provides higher autofocus accuracy.
Some Alpha-mount lenses attached via the LA-EA1 mount adapter that's running current firmware can also be used with the NEX-C3's contrast detection autofocus system, but only if they use an in-lens autofocus motor. That rules out screw-drive lens models, which must be focused manually when using this adapter. Since Alpha-mount lenses weren't designed with contrast detection autofocus operation in mind, performance may suffer to varying degrees--depending on the lens model--both in terms of AF speed and power consumption. If shooting video, lens drive noise may prove objectionable.
With the alternate LA-EA2 mount adapter, the NEX-series cameras are uniquely able to provide for phase detection autofocusing with Alpha-mount lenses, courtesy of a dedicated phase detect sensor. They do this in basically the same way as Sony's Translucent Mirror-based SLT-series cameras. A partially reflective mirror is placed in the optical path, sending a portion of incoming light to the dedicated 15-point autofocus sensor. Unlike the earlier mount adapter, the LA-EA2 provides support for screw-drive lenses, thanks to a built-in autofocus motor. Since it doesn't rely on the stepped motion of contrast detection AF, it should also provide significantly better AF performance even with lenses that include their own AF motors. Of course, AF drive noise may still prove an issue, depending on the lens model in use.
The Sony NEX-C3 includes a bright orange LED lamp at the top of the hand grip, which serves as an AF assist illuminator. With relatively limited space available on the body, it's quite easy to accidentally obscure with your fingertips, especially if you have large hands. It's also likely to be obscured by larger lenses, and can't be used with Alpha-mount lenses attached via the LA-EA2 mount adapter. It serves its purpose quite well for nearby subjects with the kit lenses, however.
The Sony NEX-C3 features an electromagnetic vibration dust-reduction system, coupled with a charge protection coating on its low-pass filter that aims to prevent dust adhering -- especially important since the NEX-C3's shutter is normally open for full-time Live View. The vibration seems to be at a rather lower frequency than some competing systems (or perhaps to have a harmonic at a lower frequency), because it's clearly audible as a brief, high-pitched whine when operating. The system automatically runs only at power-off, meaning that it doesn't delay camera startup. It can also be triggered at any time while using the camera, should you notice that dust specks are present in your images. Interestingly, the sound when operating manually has a slightly higher pitch than that when operating at power-off, suggesting the frequencies used differ between the two cycles.
Sony NEX-C3 Optical Test Results
Below are the results of our optical tests with the Sony NEX-C3 and the bundled E 18-55mm f/3.5-5.6 OSS kit lens. The test images shown on most other pages of this review were taken with very sharp references lenses, so we use this page to explore kit lens quality.
Lens Test Results
A typical 3x zoom ratio, with average performance.
|18mm @ f/8||55mm @ f/8|
The Sony NEX-C3 is available bundled with an E 18-55mm f/3.5-5.6 OSS lens. This optically stabilized lens possesses a typical optical zoom ratio of about 3x, with a 35mm equivalent focal range of about 27-83mm because of the NEX-C3's 1.5x "crop factor". Sharpness at wide-angle was pretty good at f/8. Some chromatic aberration is however evident along the edges and corners, and some flare is visible around the building's white surfaces. Results at the 55mm setting were also pretty good at f/8, with much lower levels of chromatic aberration and less flare. See below for comments on macro performance, geometric distortion, corner softness, etc.
An average sized minimum coverage area, with good detail. Flash throttled down reasonably well.
|Macro with 18-55mm
kit lens (55mm @ f/8)
|Macro with Flash|
As with zoom performance, the Sony NEX-C3's macro performance will depend entirely on the lens in use. However with the E 18-55mm kit lens set to 55mm, the NEX-C3 captured an average sized minimum area measuring 3.01 x 2.00 inches (77 x 51 millimeters). Detail was good in the center at f/8, just a touch soft, though corners and edges of the frame were much softer. (Most lenses have some softening in the corners at macro distances.) The flash did a pretty good job throttling down, resulting in good though slightly dim exposure. The flash also had no trouble clearing the lens as there is no detectable shadow, though coverage was a little uneven with the bottom and corners of the image is a little dimmer than the rest.
Higher than average geometric distortion at wide-angle and telephoto.
|Barrel distortion at 18mm is 1.1 percent|
|Pincushion distortion at 55mm is 0.5 percent|
The Sony NEX-C3's E 18-55mm kit lens produced about 1.1 percent barrel distortion at wide-angle, which is higher than average and noticeable in some of its images. At the telephoto end, there's about 0.5% pincushion distortion, also higher than average but not quite as 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).
The Sony NEX-C3 does not appear to be applying any geometric distortion correction to its JPEGs, as uncorrected RAW files show the same amount of distortion.
Chromatic Aberration and Corner Sharpness
High chromatic aberration at wide-angle; much lower levels at full telephoto. The lens produced some pretty soft corners wide-open, but improved when stopped-down.
Chromatic Aberration. Chromatic aberration in the corners with the NEX-C3's 18-55mm kit lens at wide-angle (18mm) is moderate in terms of the number of pixels, but quite bright, so the effect is noticeable in the softer corners and edges of some shots. At full telephoto (55mm), CA is moderate in terms of number of pixels, but the colors in the fringes are very muted, so CA was quite low overall. Color fringing gradually reduces in brightness and width as it approaches the center of the image, where it is very low at both wide-angle and telephoto.
Corner Softness. Wide-open at full wide-angle, the 18-55mm lens that came with our NEX-C3 was pretty soft in the left corners, with the top left being the softest. Softness extended pretty far into the frame as well. Corners on the right were much sharper, though some flare was noticeable, while the center of the image was sharp with very good contrast. Some minor vignetting (corner shading) is also noticeable at full wide-angle, as indicated by the darker corner crop. At full telephoto, all four corners were soft with the left side being softer than the right, though the center was pretty sharp. Softness didn't extend quite as far into the frame as it did at wide-angle. The lens also had lower contrast overall at full telephoto compared to wide-angle.
|18mm@f/8: Lower left
C.A.: Moderately high and bright
Softness: Minor blurring
|55mm@f/8: Lower left
Softness: Moderate blurring
C.A.: Very low
"Stopped-down" to f/8, corner sharpness at wide-angle improved dramatically compared to wide-open at f/3.5, though CA was still high. At full telephoto, sharpness also improved at f/8 versus wide-open at f/5.6, but corners were still soft with lower contrast.
Overall, an average performance for a kit lens.
The images above were taken from our standardized test shots. For a collection of more pictorial photos, see our Sony Alpha NEX-C3 Photo Gallery .
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