Handling and Features
Performance
Verdict
Specification
This 6x zoom lens sports a constant maximum aperture of f/4 throughout the zoom range, a powered zoom system with two separate controls, internal focusing and zoom and optical stabilisation.
As this lens carries Sony's 'G' moniker, it is one of their premium lenses, even so, the price seems quite reasonable, at around £450. Could this be too good to be true? We'll investigate in this review.
Sony 18-105mm f/4 PZ G OSS Handling and Features
Build and design is typical of Sony's premium E-Mount lenses, with a robust aluminium outer lens barrel and a metal lens mount. Despite the large size of this lens, it is reasonably light weight, weighing only 427g, . Even with the large size of the lens, the low weight ensures the lens will match up perfectly with even the most compact NEX series camera bodies, and it handles very well on the NEX-7 used for testing.
Auto focus is reasonably fast locking onto subjects accurately. Applying manual focus adjustments is a pleasure, thanks to the smooth action of the focusing ring, which is nicely damped. Minimum focus varies throughout the zoom range, being 45cm at 18mm and 95cm at 105mm.
As focusing and zooming are performed internally, the 72mm filter ring does not rotate, which makes the lens ideal for use with graduated and polarising filters. A deep petal-shaped lens hood is supplied as standard, which attaches to the lens via a bayonet fitting.
The lens seems geared more towards video than stills, with a camcorder style tele/wide zoom control accompanying a zoom ring that can be rotated. There is a slight delay in operation with either control, although zooming can be performed very smoothly, which will suit video very well. There is a noticeable delay when switching on the camera with this lens attached, as the lens prepares itself for use and resets the zoom to 18mm each time.
For those times when slow shutter speeds are necessary, this lens comes equipped with optical image stabilisation. With care, sharp hand-held images can be taken at shutter speeds as slow as 1/20sec, which is roughly three stops slower than the usual rule of thumb for hand-held photography would allow.
Sony 18-105mm f/4 PZ G OSS Performance
Sharpness is already excellent in the centre of the frame at maximum aperture and 18mm, with very good clarity being recorded towards the edges of the frame. Stopping down improves performance across the frame, with peak clarity being achieved at f/5.6. Here sharpness is outstanding in the centre and excellent towards the edges of the frame.
Zooming to 45mm results in improved performance at maximum aperture. Here sharpness in the centre is outstanding and clarity towards the edges of the frame is very good. Stopping down to f/5.6 results in peak performance across the frame. Here sharpness is outstanding in the centre of the frame, and excellent towards the edges of the frame.
Finally, at 105mm, performance in the centre of the frame remains outstanding, although sharpness towards the edges of the frame appears to fall off a cliff, only achieving fairly good levels. Stopping down to f/8 results in the best performance, with outstanding sharpness in the centre and clarity that falls just short of good levels towards the edges of the frame.
MTF@18mm |
MTF@45mm |
MTF@105mm |
How to read our chartsThe blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges. Averaging them out gives the red weighted column.The scale on the left side is an indication of actual image resolution. The taller the column, the better the lens performance. Simple. For this review, the lens was tested on a Sony NEX-7 using Imatest. |
Chromatic aberrations are prevalent towards the edges of the frame, regularly exceeding 1 pixel width and even 2 pixel widths at 105mm. This level of fringing may become visible along high contrast edges placed near the edges of the frame.
CA@18mm |
CA@45mm |
CA@105mm |
How to read our chartsChromatic aberration is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more. For this review, the lens was tested on a Sony NEX-7 using Imatest. |
Falloff of illumination towards the corners of the frame is well controlled. At 18mm the corners of the frame are 0.98 stops darker than the image centre at f/4 and at 105mm the corners are 0.91 stops darker. Visually uniform illumination is achieved with the lens stopped down to f/5.6 or beyond throughout the zoom range.
The distortion this lens produces is quite noticeable. At 18mm 0.495% pincushion distortion is present, which is replaced with 7.2% pincushion distortion at 105mm. The NEX 7 used for testing automatically corrects JPEG images once they are taken, which results in the image jumping about wildly on the screen as the corrections are applied. As the correction applied is effectively stretching the centre of the frame, this will result in reduced resolution in JPEG images. RAW images are left uncorrected.
The supplied lens hood does an excellent job of shielding the lens from extraneous light that may cause issues with flare. Even without the hood this lens is quite resistant to flare and retains contrast well when shooting into the light.
Sony 18-105mm f/4 PZ G OSS Sample Photos
As the distortion of the lens is very noticeable when shooting RAW images, we have included examples showing the JPEG images corrected in-camera, as well as in Adobe Photoshop below - using Adobe Photoshop CS6 and Camera Raw 8.4 beta. For those that shoot JPEG only, you are unlikely to see the distortion at the telephoto end of the lens.
Value For Money
This lens can be picked up for around £450, which seems quite good value for money, given the specification of this lens. There are no direct alternatives covering the same range, with the same aperture at the moment. The closest is probably the Sony 18-200mm f/3.5-6.3 OSS LE lens, which gains at the telephoto end and costs £550.
Sony 18-105mm f/4 PZ G OSS Verdict
Clearly, as this lens is aimed at video shooters, some of the optical issues may not be a concern for people recording moving images with this lens on an NEX camera. In fact, it is very good for this job.
Those shooting stills may be wary of the poor performance towards the edges of the frame at the telephoto end of the zoom, and the wild distortion that is present, as well as the high levels of fringing present. These issues make the lens difficult to recommend to those who may shoot stills with this lens, unless shooting JPEG only.