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
Image: These shots illustrate the results of the charts shown earlier. At its largest aperture, the Zeiss 50mm f/1.4 lens is extremely
soft. Stop the lens down to f/8 and it becomes one of the sharpest in
While the resolution graphs of each lens look very similar, there are a few models that really stand out. Most notable are the Zeiss Planar T* 50mm f/1.4 and Zeiss Makro-Planar T* 50mm f/2. At 1 stop down from the minimum aperture, both these lenses perform exceptionally well, with the f/1.4 resolving the most detail of any lens in the test. While the Zeiss f/1.4 is extremely sharp at f/8 and f/11, it is, along with the Zeiss f/2 macro, the worst lens on test here when shooting with the aperture wide open at f/1.4. Similarly, the performance of the Pentax SMC DA* 55mm f/1.4 SDM isn’t particularly great when wide open, with the corners and edges resolving almost the same amount of detail.
Of all the lenses on test here, the Nikkor AF-S 50mm f/1.4G, Zeiss Planar T* 50mm f/1.4 and Zeiss Makro-Planar T* 50mm f/2 suffer the most from vignetting wide open, with the effects very noticeable in grey-chart images. The test graphs show that the lenses produce around -0.6EV of difference in brightness between the centre and edges.
An interesting point about the Pentax SMC DA 50mm f/1.8 is that the vignetting is slightly worse on the right-hand side of the frame compared to the left. This can be seen in graphical form in the test chart on page 47. Although the vignetting isn’t very severe, and there is only around 0.1EV difference between the left and right sides, it does mean that it is slightly more awkward to correct in software, and may require shifting any correction off centre, or creating a custom profile, which will be a better solution in the long term.
Image: Curvature is clearly visible at the top of this image taken with the Sony Carl Zeiss 50mm f/1.4 lens
Of the best performers, the Canon EF 50mm f/1.8 II shows the least vignetting, followed by the Sigma 50mm f/1.4 EX DG HSM and Sigma 50mm f/2.8mm Macro EX DG. All three lenses have a less than -0.2EV difference between the edge and centre of the image frame. As expected from a 50mm lens, none of these suffers particularly badly from curvilinear distortion. Obviously, the smaller f/2.8 aperture of the Sigma 50mm f/2.8mm macro means it has a smaller front element with less curvature, as shown by the maximum distortion of the lens at just -0.7%, with a mean distortion of
The Pentax 50mm f/1.8 has an almost identical performance to the Sigma 50mm f/2.8mm macro. It suffers slightly less at its worst, with just -0.6% distortion, but as a mean it shows a fractional -0.1% average across the frame. The Zeiss 50mm f/2 shows similar results (-0.6 maximum and -0.2 mean). The remainder of the f/1.8 lenses show a similar performance, distorting between -1.3% and -1.8%.
With a larger curved glass surface, it would be expected that the 50mm f/1.4 lenses would suffer more from distortion, but the Pentax 55mm f/1.4 bucks this trend. In fact, for distortion, this lens is
the third best on test and the best f/1.4 lens. It has a maximum distortion of just -0.7%, with a -0.2% average. The Sony Carl Zeiss Planar T* 50mm f/1.4 SSM lens is the worst, with a maximum distortion of -2.3% and a mean of -0.6%, and the Zeiss 50mm f/1.4 is very similar with a -2.1 and -0.5% reading. There is very little to pick between the Sigma 50mm f/1.4, with its maximum distortion of -1.7% and mean of -0.4%, and the Canon EF 50mm f/1.4 USM and Nikon AF-S 50mm f/1.4G lenses, which both show almost identical distortion figures of -1.8 and -1.4 maximum, and -0.4% mean.
However, in real-life examples it is only the worst performing lenses that have noticeable distortion, and unless you are shooting architecture you may not notice the slight bend on some of the f/1.4 lenses. Given the very small percentages that are involved in the level of distortion, it shouldn’t be a cause for concern.
Image: These images above were shot with the Nikkor 50mm f/1.4G lens and are a good example of the resolution of a lens across the aperture settings
Despite there being some significant differences in how these 50mm lenses have performed in our lab tests, none of them is terrible. For example, the Zeiss Planar T* 50mm f/1.4 lens is very soft when used at its maximum aperture, yet it can resolve the most detail when shooting at its best aperture. Also, while the Nikkor AF-S 50mm f/1.4G may vignette quite badly at its maximum aperture, it is easy to remove in software and virtually disappears if the aperture is stopped down 2 stops.
So, basically, which of the lenses will be the best for you will really depend on what you want to do with it and the camera that you own. Generally the 50mm f/1.8 lenses have the best all-round performance. They show the least distortion, have the least degradation in resolution across the aperture range and are the best value for money. As the shots on page 45 show, there is very little difference between shooting at f/1.4 and f/1.8 in terms of depth of field, so we would recommend that most photographers will be best suited to buying an f/1.8 lens. In particular, the Nikon AF-S 50mm f/1.8G has great performance throughout the entire range, even when shooting wide open. Sigma’s f/1.4 is a good all-round lens, and despite its inexpensive construction, the Canon EF 50mm f/1.8 II resolves a great deal of detail.
Perhaps the biggest surprise is the performance of the two Zeiss lenses. Heralded by many as the pinnacle of lens design, the image quality of these two models doesn’t match their superb metal construction. Both lenses are soft wide open, and it is clearly an old optical design that has now been bettered. When stopped down the lenses are the best on test, but this is a little restrictive unless you are only ever going to use your lens at f/5.6-f/11. However, the build quality is great, and for those who shoot street pictures and manually focus, they are nice lenses.
Of the f/1.4 lenses, we liked the Pentax SMC DA* 55mm SDM. Although it has a fractionally longer focal length than the other lenses in this test, it has little vignetting or distortion compared to its contemporaries, and is well constructed with a quiet Sonic Drive Motor.
Canon’s EF 50mm f/1.4 USM doesn’t quite match the Nikkor AF-S 50mm f/1.4G in terms of resolution, but it does create less distortion and vignetting. The Sigma 50mm f/1.4 EX DG HSM is also no slouch, and is certainly comparable to the Canon and Nikon lenses. The Sony Carl Zeiss Planar T* 50mm f/1.4 SSM lens is also sharp, and has a nicely designed body, but at more than £1,000 there are more affordable options.