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50mm lens test – Introduction

For many years, the 50mm focal-length lens was a staple of photography. Not only was it the optic of choice for many photographers, but with virtually every new SLR coming paired with a 50mm lens it was also many people’s first – and sometimes only – lens.

The reason for the popularity of such optics was that the 50mm focal length best replicates the focal length and central field of view of the human eye. The design was usually simple, with a minimal amount of glass, so, as a result, 50mm lenses are among the sharpest ever made, and virtually free from curvilinear distortions. This focal length also means that large apertures are possible without
the need for gigantic glass optics.

The reign of the 50mm lens ended in the 1980s when manufacturers began to offer SLRs with modest zoom lenses, and as these became more affordable they were soon the norm. However, despite the fact that many photographers now opt for complex zooms, the 50mm prime is still often the sharpest lens in a manufacturer’s range, and the f/1.8 varieties are also usually the cheapest. For instance, an f/1.8 can be bought new for less than £200, and used prices can even be under £100. With the 50mm focal length great for documentary, landscape and portrait images, there really is no excuse not to own one, but the question is, which one do you choose?

We have tested 12 lenses from Canon, Nikon, Pentax, Sigma, Sony and Zeiss to find out which 50mm optic is sharpest, which handles the best and which shows the least distortion. Each has been tested on an appropriate enthusiast-level camera, so the results reflect how they will work on that system.

50mm lens test – Which aperture?

Image: Lenses with an f/1.8 aperture are not only the most affordable, but also the best compromise

With a few different apertures available when choosing a 50mm lens, it can be tricky to know which one to go for. Lenses with an f/1.8 aperture are usually the cheaper, followed by the f/2.8 lenses, which are usually macros. The most expensive lenses are generally the f/1.4 models. This is due to their larger size and the fact that they require more glass.

Obviously, the difference in aperture affects the amount of light passing through the optic. A large aperture increases the ability to shoot in low light, or at a short shutter speed, but it has other advantages. Lenses are generally at their sharpest when the aperture is reduced by 2 stops. Two stops down from f/1.4 is f/2.8, meaning that an f/1.4 lens should be far sharper at f/2.8 than a lens with a f/2.8 maximum aperture. It’s a similar story with an f/1.8 lens, which should be sharper at f/2.8.

Depth of field is also affected. The f/1.4 lens offers an extremely shallow depth of field, but it won’t necessarily be very sharp at its maximum aperture. Stop it down 2 stops and not only will it have the same depth of field as a f/2.8 lens, but it should also be sharper.

The downside of lenses with a f/1.4 maximum aperture is their expense and size. In practice, the f/1.8 aperture only reduces light by 0.3EV, which for most photographers is not a significant difference.

All the f/1.8 lenses have a largely plastic construction and, with the exception of the Nikkors, they all have plastic lens mounts. The Nikkor has the best build quality of the f/1.8 lenses. It is also the largest and weighs the most, although it is by no means heavy.

The Pentax SMC DA 50mm f/1.8 also feels nice in the hand. It is the smallest 50mm lens in this test, but despite its plastic construction it feels solid. Sony’s DT 50mm f/1.8 SAM also feels reasonably solid. However, the extremely light Canon EF 50mm f/1.8 II is the least pleasant to handle. Although its build can’t be faulted – there’s no creaking and little movement to the barrel – it does feel rather cheap.

The plastic focusing ring of the Canon f/1.8 is similar to that found on the Pentax f/1.8, being very slim with a moulded ridge offering some purchase. The Sony f/1.8 lens has the least pleasant ring – there’s no grip and its gears are extremely noisy, even when manually focusing. For us, though, the best of the bunch in terms of build is the Nikkor AF-S 50mm f/1.8G. It’s the nicest to use when manually focusing, while the larger barrel, wide-ridged rubber grip and clutch switch that lets you manually adjust focus – even with the camera in AF mode – make it the best built f/1.8 lens in this group test.

The Zeiss Planar T* 50mm f/1.4 is the smallest of the f/1.4 lenses, but is the most solidly constructed. Its reassuringly weighty, all-metal design and smooth focusing ring make it a high-quality product reminiscent of a classic 50mm from the 1960s. This lens has to be focused manually, but it’s the lack of autofocus that means it can be smaller and, of course, you are spared the dirty background noise that AF motors emit as they grind and turn.

The Nikkor AF-S 50mm f/1.4G and Canon EF 50mm f/1.4 USM lenses are very alike in size and construction, although the Nikkor’s motor is fractionally quieter and it is the nicer to focus manually. Pentax’s SMC DA* 55mm f/1.4 SDM weighs more than both its Canon and Nikkor equivalents, and it has an extremely good, large, manual focus ring. The Sonic Drive Motor (SDM) is fairly quiet and overall the build of the lens is of the quality we have grown to expect from Pentax products at this level.

Both the Sigma 50mm f/1.4 EX DG HSM and Sony Carl Zeiss Planar T* 50mm f/1.4 SSM lenses are large and heavy. The Sony Carl Zeiss lens has the high build quality we expect from this partnership, with a reassuringly solid metal exterior and a plastic ridged focusing ring. It is extremely nice to hold and use, although its weight means it is really best partnered with the Alpha 77 and 99.

The exterior design of the Sigma f/1.4 will be familiar to anyone who has used a Sigma lens over the past few years, with a good manual-focusing ring and a semi-matt textured finish, which makes the lens easy to hold. This lens doesn’t feature the aperture ring that some slightly older Sigma models carried.

Although both the Zeiss Makro-Planar T* 50mm f/2 macro and Sigma 50mm f/2.8 Macro EX DG are around the same size, they are very different terms of weight. The manual-focus Zeiss has a premium feel thanks to its solid all-metal construction, which partly accounts for it being rather heavy for its size. The Sigma lens is lighter, but it has a good grip to the focus ring and a nice finish. As it has autofocus it has a limit switch that can restrict focusing to its closest focus distance for macro.

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.

Specificiations: Canon EF 50mm f/1.4 USM

RRP: £539.99Street price: Around £280
Filter diameter: 58mm
Lens elements: 7
Groups: 6
Diaphragm blades: 8
Aperture: f/1.4-22
Minimum focus: 45cm
Length: 50.5mm
Diameter: 73.8mm
Weight: 290g
Lens mount: Canon EF

Chart analysis

Tested on a Canon EOS 5D Mark III

For a lens with an f/1.4 aperture, the Canon EF 50mm f/1.4 USM shows little vignetting. Curvilinear distortion is also kept to a reasonable level, although some correction will be required for straight edges right at the limit of the frame. The lens can resolve a reasonable amount of detail, and although it is far better than the Carl Zeiss lenses when shooting fully open, it can’t quite match the detail resolution of the Sigma f/1.4 lens at maximum aperture. That said, the closeness of the blue and green lines indicates that it is sharp across the frame, and with little difference in resolution from f/2.8 to f/11.

Score: 5 out of 5

Specififications: Canon EF 50mm f/1.8 II

RRP: £129.99Street price: Around £82
Filter diameter: 52mm
Lens elements: 6
Groups: 5
Diaphragm blades: 5
Aperture: f/1.8-22
Minimum focus: 45cm
Length: 41mm
Diameter: 68.2mm
Weight: 130g
Lens mount: Canon EF

Chart analysis

Tested on a Canon EOS 5D Mark III

From the test charts it is clear that the Canon EF 50mm f/1.8 II is one of the best lenses in this group. The almost flat vignetting chart shows that there is little difference in brightness from the centre to the corners. The curvilinear distortion figures are also extremely low. Resolution detail, on the other hand, is high, particularly when shooting 2 stops down from the maximum even when shooting with the aperture at its largest f/1.8 setting. The fact that the green lines are so close together tells us that there is little difference in edge and corner sharpness when shooting at f/11.

Score: 4 out of 5

Specifications: Nikon Nikkor AF-S 50mm f/1.4G

RRP: £375.99
Street price: Around £290
Filter diameter:
58mm
Lens elements:
8
Groups:
7
Diaphragm blades:
9
Aperture:
f/1.4-16
Minimum focus:
45cm
Length:
54mm
Diameter:
73.5mm
Weight:
280g
Lens mount:
Nikon F

Chart analysis

Tested on a Nikon D600

Like some of the other f/1.4 lenses, the Nikkor AF-S 50mm f/1.4G suffers from some quite harsh vignetting when the aperture is fully open, as indicated by the deep dome on the 3D illustration. Curvilinear distortion is reasonably well controlled, and only at the very edges is there any real distortion. Overall, the Nikkor is one of the better f/1.4 lenses in this respect. In terms of resolution detail, the Nikkor f/1.4 is one of the best performers in this test. Even when shooting at f/1.4, it betters many of its rivals and this excellent performance reaches a peak between f/4 and f/8.

Score: 5 out of 5

Specifications: Nikon Nikkor AF-S 50mm f/1.8G

RRP: £199.99
Street price: Around £155
Filter diameter:
58mm
Lens elements:
7
Groups:
6
Diaphragm blades:
7
Aperture:
f/1.8-16
Minimum focus:
45cm
Length:
52.5mm
Diameter:
72mm
Weight:
185g
Lens mount:
Nikon F

Chart analysis

Tested on a Nikon D600

The Nikkor AF-S 50mm f/1.8G lens is particularly impressive as its resolution only drops very slightly when it is used fully open. This is great for those who want to really take advantage of the f/1.8 aperture. Overall, the resolution is very good, especially when the cost of the lens is taken into account.

The shading graph shows that when fully open the lens does suffer from vignetting that is around -0.3EV darker at the edges, although this is not really a problem. Looking at the curvilinear distortion values, the Nikkor 50mm f/1.8G lens is on a par with comparable lenses from Canon and Sony.

Score: 5 out of 5

Specifications: Pentax SMC DA* 55mm f/1.4 SDM

RRP: £759.99Street price: Around £610
Filter diameter:
58mm
Lens elements:
9
Groups:
8
Diaphragm blades:
9
Aperture:
f/1.4-22
Minimum focus:
45cm
Length:
66mm
Diameter:
70.5mm
Weight:
375g
Lens mount:
Pentax K

Chart analysis

Tested on a Pentax K-5 II

Pentax’s SMC DA* 55mm f/1.4 SDM lens has an impressively low level of curvilinear distortion. In fact, it’s the third best result for a lens in this test. Vignetting is also kept to a bare minimum.

Resolution is good, although the f/1.8 is better, particularly at 1 stop down from the minimum aperture. The light-green line is quite far from the dark green, showing that there is quite a difference is sharpness between the centre and edge.

Score: 4 out of 5

Specifications: Pentax SMC DA 50mm f/1.8

RRP: £249.99
Street price: Around £220
Filter diameter:
52mm
Lens elements:
6
Groups:
5
Diaphragm blades:
7
Aperture:
f/1.8-22
Minimum focus:
45cm
Length:
63mm
Diameter:
38.5mm
Weight:
122g
Lens mount:
Pentax K

Chart analysis

Tested on a Pentax K-5 II

The most noticeable thing about the Pentax SMC DA 50mm f/1.8 is that on the lens we had, there
was slightly more vignetting on one side than on the other. Although this 0.1EV difference is noticeable in the illustration, it was indistinguishable under real shooting conditions. Curvilinear distortion is also slightly uneven, although there is little here to be concerned about as it is fairly weak. As for resolution, the lens is good 2 stops down and 1 stop from minimum, so it has a good
working range.

Score: 4 out of 5

Specificiations: Sigma 50mm f/1.4 EX DG HSM

RRP: £459.99
Street price:
Around £350
Filter diameter:
77mm
Lens elements:
8
Groups:
6
Diaphragm blades:
9
Aperture:
f/1.4-16
Minimum focus:
45cm
Length:
68.2mm
Diameter:
84.5mm
Weight:
505g
Lens mount:
Canon EF, Nikon F, Sony A, Pentax K, Sigma

Chart analysis

Tested on a Canon EOS 5D Mark III

The shading graph of the Sigma 50mm f/1.4 EX DG HSM is particularly impressive and looks more like the graph of an f/1.8 lens. Curvilinear distortion is reasonable for an f/1.4 lens, although images with straight lines close to the limits of the frame may require a little nudge to get them perfectly straight.

Resolution is very good and, although there is a noticeable drop in image quality when working at f/1.4, the graph puts the Carl Zeiss f/1.4 lens to shame. Overall, the Sigma f/1.4 lens should warrant the attention of most DSLR users, especially as it is available in all major lens mounts.

Score: 5 out of 5

Specifications: Sigma 50mm f/2.8 Macro EX DG

RRP: £319.99Street price: Around £270
Filter diameter:
55mm
Lens elements:
10
Groups:
9
Diaphragm blades:
7
Aperture:
f/2.8-45
Minimum focus:
18.8cm
Length:
66.5mm
Diameter:
71.4mm
Weight:
320g
Lens mount:
Canon EF, Nikon F, Sony A, Pentax K, Sigma

Chart analysis

Tested on a Canon EOS 5D Mark III

As a macro lens, the Sigma 50mm f/2.8 Macro EX DG has been designed with precision in mind and the lack of long arrows on the distortion diagram show that only at the very edges is there any curvilinear distortion. This translates to the lens having an average distortion value of

Score: 4 out of 5

Specifications: Sony Carl Zeiss Planar T* 50mm f/1.4 SSM

RRP: £1,299
Street price: £1,299
Filter diameter:
72mm
Lens elements:
8
Groups:
5
Diaphragm blades:
9
Aperture:
f/1.4-22
Minimum focus:
45cm
Length:
71.5mm
Diameter:
81mm
Weight:
518g
Lens mount:
Sony Alpha

Chart analysis

Tested on a Sony Alpha 99

There is quite a spread of the different lines on the resolution graph, showing a real difference between the sharpness at the centre and edges of images taken on the Sony Carl Zeiss Planar T* 50mm f/1.4 SSM lens. It is also worth noting that the corners really suffer from diffraction when the aperture is at f/16, but the centre is almost at its sharpest. Vignetting is well controlled, as the fairly shallow dome indicates, but curvilinear distortion is quite harsh and will need correcting when shooting raw images.

Score: 4 out of 5

Specifications: Sony DT 50mm f/1.8 SAM

RRP: £159Street price: Around £115
Filter diameter: 49mm
Lens elements: 6
Groups: 5
Diaphragm blades: 7
Aperture: f/1.8-22
Minimum focus: 34cm
Length: 45mm
Diameter: 70mm
Weight: 170g
Lens mount: Sony Alpha DT (APS-C only)

Chart analysis

Tested on a Sony Alpha 58

Although the edges of the Sony DT 50mm f/1.8 SAM lens aren’t very sharp when shooting a f/1.8, the centre is almost as sharp as when the lens aperture has been stopped down. This is common with other f/1.8 lenses released over the past couple of years. The dome shape of the shading illustration shows that the lens vignettes more than most of the other f/1.8 lenses on test here, although it isn’t as bad as the Nikon equivalent. Curvilinear distortion could also be better when compared to some of its counterparts, although again, it is comparable to the equivalent Nikkor lens.

Score: 4 out of 5

Specifications: Zeiss Planar T* 50mm f/1.4

RRP: N/A
Street price: Around £600-£620
Filter diameter:
58mm
Lens elements:
7
Groups:
6
Diaphragm blades:
9
Aperture:
f/1.4-16
Minimum focus:
45cm
Length:
69/71mm
Diameter:
66/71mm
Weight:
330-380g
Lens mount:
Canon EF, Nikon F

Chart analysis

Tested on a Nikon D600

The resolution detail of the Zeiss Planar T* 50mm f/1.4 is something of an oddity in this lens round-up. It clearly shows that the lens is very poor when wide open, and is actually sharper when shooting at f/11 rather than 2 stops down at f/2.8.

Conversely, it is the best lens when used at its maximum potential, and when paired with the Nikon D600 the results are excellent.

However, this lens does suffer from curvilinear distortion, and vignetting causes the edges of the image to be almost -0.6EV darker than at the centre of the frame.

Score: 4 out of 5

Specifications: Zeiss Makro-planar T* 50mm f/2

RRP: N/AStreet price: Around £1,070-£1,100
Filter diameter:
67mm
Lens elements:
8
Groups:
6
Diaphragm blades:
9
Aperture:
f/2-22
Minimum focus:
24cm
Length:
88/91mm
Diameter:
72/75mm
Weight:
500-570g
Lens mount:
Canon EF, Nikon F

Chart analysis

Tested on a Nikon D600

Like its f/1.4 counterpart, the Zeiss Makro-Planar T* 50mm f/2 suffers from quite bad vignetting when shooting wide open, with the edges around -0.6EV darker than the centre. However, it has less curvilinear distortion.

Again, the aperture needs to be stopped down by more than 2 stops to get the best from the lens. At its sharpest, the lens is one of the best on test, although to achieve this it needs to be used in a restrictive aperture range of between f/8 and f/11.

Score: 4 out of 5


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
this test

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

Our verdict

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.