The 50mm focal-length lens is a true photographic icon and an essential piece of kit for any photographeru2019s kit bag, but there are quite a few to choose from. Richard Sibley and Andrew Sydenham test 12 such optics to assess their particular qualities
Our lens charts are created using industry-standard software. Each of the lenses has been tested on an appropriate camera, with the Canon EOS 5D Mark III, Nikon D600, Pentax K-5 II, Sony Alpha 99 and Sony Alpha 58 being used.
The MTF charts show clarity on their vertical axes and the number of line pairs per picture height of the target along the horizontal axes. As the number of line pairs per picture height increases, the lens is less able to define them, hence the downward curve in these graphs.
The shading graph shows a 3D representation of the vignetting that occurs on the sensor. A red portion of the graph represents almost a -1EV reduction in the corners, while a completely flat green graph shows there is no vignetting at all.
In the curvilinear distortion chart the small arrows represent the direction of the distortion shift. In the centre of the chart the two numbers show how much the lines bend away from the ‘normal’, with the ‘Max’ measuring the greatest shift and the ‘Mean’ the average over the whole chart.