Sony 50mm f/2.8 macro ( SAL-50M28 ) - Review / Test Report - Analysis
Lens Reviews - Sony Alpha/NEX (APS-C)
Friday, 08 August 2008 10:00

Distortion

Typical for all macro lenses the Sony 50mm f/2.8 macro produces images which are basically free of distortion (~0.18%).

The chart above has a real-world size of about 120x80cm.

Vignetting

The Sony 50mm f/2.8 macro is a full format lens and as such enjoying the usual sweet spot advantage when used on an APS-C DSLR. Within this scope the lens shows moderate vignetting at f/2.8 (0.65EV) and the problem is pretty much negligible from f/4 onwards.

MTF (resolution)

The Sony 50mm f/2.8 macro produced very good to excellent resolution figures in the MTF lab. At f/2.8 you can expect an excellent center quality and very good borders. The performance peak is reached around f/5.6 with an excellent resolution across the frame. The quality is still very acceptable at f/16 but you should avoid smaller apertures beyond due to diffraction effects.

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

Lateral chromatic aberrations (color shadows at harsh contrast transitions) are fairly high for a fix-focal lens with an average pixel width between 1.3px and 0.7px at the image borders. However, this is still moderate from a global perspective and usually no problem in field conditions.

Bokeh

The quality of the bokeh is a primary playground for a macro lens and the Sony lens is capable of producing very decent results here. The rounded aperture shape in out-of-focus highlights remains intact at f/2.8 and f/4 but circular shapes are somewhat distorted towards ellipsoids near the image borders. The blur is very smooth and uniform.

Longitudinal (Axial) Chromatic Aberrations (LoCA)

LoCAs (non-coinciding focal planes of the various colors), sometimes called "bokeh CAs", may be visible in very critical scenes at f/2.8. As you can notice below the halos have different colors - magenta (red + blue) in front the focus point and green beyond. It's not a real issue anymore from f/4 onwards.

Move the mouse cursor over the f-stop marks below to observe the respective LoCAs
f/2.8 f/4




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