Carl Zeiss Vario-Tessar E 16-70mm f/4 ZA OSS T* Review

Zeiss Vario-Tessar T* E 16-70mm f/4 ZA OSS Performance

Sharpness is already outstanding in the centre of the frame at maximum aperture and 16mm, with very good clarity being recorded towards the edges of the frame. At this focal length, diffraction appears to be the limiting factor for performance, as stopping down doesn't improve sharpness at all, although similar performance is maintained with the lens stopped down to f/5.6 and f/8.

Zooming to 35mm results in reduced performance at maximum aperture. Here sharpness in the centre is still excellent, but clarity towards the edges of the frame has dropped to fairly good levels. Stopping down to f/5.6 results in peak performance across the frame. Here sharpness is outstanding in the centre of the frame, and very good towards the edges of the frame.

Finally, At 70mm, performance evens out across the frame and sharpness is very good across the frame at maximum aperture. Stopping down to between f/5.6 and f/8 results in the best performance, with outstanding sharpness in the centre and excellent clarity towards the edges of the frame.

MTF@16mm

MTF@35mm

MTF@70mm

How to read our charts The 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 quite high, towards the edges of the frame, regularly exceeding 1 pixel width and even 1.5 pixel widths at 16mm and 70mm. This level of fringing may become visible along high contrast edges placed near the edges fo the frame, such as tree branches, or the tops of buildings.

CA@16mm

CA@35mm

CA@70mm

How to read our charts Chromatic 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 16mm the corners of the frame are 0.98 stops darker than the image centre at f/4 and at 70mm the corners are 0.81 stops darker. Visually uniform illumination  is achieved with the lens stopped down to f/8 or beyond throughout the zoom range.

Distortion is reasonable at either end of the zoom range. At 16mm, 2.54% barrel distortion is present and this is replaced with 1.09% pincushion distortion at 70mm. If you require absolutely straight lines, you'll be glad to know that the distortion pattern is uniform across the frame, which should make applying correction in image editing software afterwards a doddle.

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 good contrast when shooting into the light.

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