Best prime lens for mirrorless cameras: 8 top optics tested and rated

January 13, 2016Matthew Richards

We put eight game-changing fast prime lenses for mirrorless cameras through their paces to see if they’re worth the money.

The Contenders
1   Fujifilm Fujinon XF 56mm f/1.2 R, £900 / $1,000
2   Nikon 1 Nikkor 32mm f/1.2, £650 / $720
3   Olympus M.Zuiko 25mm 1:1.8, £370 / $410
4   Olympus M.Zuiko ED 75mm 1:1.8, £720 / $800
5   Panasonic Leica DG 25mm f/1.4, £430 / $480
6   Panasonic Leica DG 42.5mm f/1.2, £1,200 / $1,335
7   Samsung 85mm f/1.4 ED SSA, £700 / $780
8   Sony Sonnar T* FE 55mm f/1.8 ZA, £850 / $945

Compact system cameras have certainly come of age. This new breed of mirrorless interchangeable lens cameras have proved to be something of a triumph of downsizing while still offering advanced photographer-friendly features and the important facility to swap lenses – you just can’t beat fitting the ideal optic for the task at hand.

Some of the latest mid-range CSCs gave a good showing against similarly-priced SLRs in a recent group test, but one downside of the mirrorless camera is that the choice of lenses can be limited.

The ranks of useful CSC lenses might be swelling, but specialised optics such as fisheye or tilt-shift lenses are hard or impossible to find.

For most photographers, the most desirable step up from a basic set of zoom lenses is a high-quality prime lens with a fast aperture.

Something with an effective focal length of around 50mm to 85mm is often ideal, as this lends itself well to street photography and portraiture. Medium telephoto focal lengths from 120mm to 150mm also find favour, for when you need more reach.

SEE MORE: 6 ways to cope with only a prime lens

Aperture size
The lenses we’ve chosen for this round-up include all of the above effective focal lengths, along with wide available apertures of between f/1.2 and f/1.8.

A major bonus of wider apertures is that, compared with a typical kit zoom lens, you can maintain much faster shutter speeds under low lighting conditions, without the need to bump up your sensitivity (ISO) setting.

For example, an aperture of f/1.4 is actually four stops faster (letting in 16 times more light) than the f/5.6 maximum found on most kit lenses at the longer end of their zoom range.

So, if you found yourself limited to a shutter speed of 1/8 sec with an f/5.6 kit lens under gloomy lighting, an f/1.4 lens would enable you to shoot at 1/125 sec.

Crop factor and DoF
Wide-aperture lenses offer an even bigger advantage when it comes to depth of field. Most compact system cameras have mid-sized image sensors, although the full-frame Sony Alpha 7-series is a notable exception. Fujifilm and Samsung cameras favour

APS-C-format sensors, similar to most SLRs, and have about a 1.5x crop factor. Olympus and Panasonic specialise in Micro Four Thirds (MFT) cameras which share the same lens mount, and which have smaller sensors, equating to a 2x crop factor. The Nikon 1 cameras have an even smaller sensor, with a 2.7x crop factor.

So how does this affect depth of field? Depth of field is governed more by the actual rather than the effective focal length of a lens. The latter value is calculated by applying the crop factor, and this can be a issue when you want a tight depth of field, most typically when you’re trying to blur fussy or distracting backgrounds in portraiture and still-life photography.

SEE MORE: Camera lenses explained: focal length, aperture, stabilisation and more

So how do these CSC lenses measure up against traditional fast glass for full-frame SLRs?

Take a classic portrait lens like the Nikon 85mm f/1.4 on a full-frame SLR. Shooting at a distance of two metres for a fairly tight head-and-shoulders portrait shot at f/1.4 will give a really tight depth of field of just 4.5cm. Using the Nikon 1’s 32mm lens gives the same effective focal length of approximately 85mm, so you’d shoot from a similar distance.

However, an f/1.4 aperture will give a depth of field that’s nearly three times larger, at 12cm. Even so, this is still usefully small, especially if you want to keep all of the face and hair sharp in a head-and-shoulder portrait. The depth of field shrinks to 10cm if you use the lens’s widest available aperture of f/1.2.

Switch to a 25mm lens on a Micro Four Thirds camera, and you’ll get an effective focal length of 50mm. You’d therefore need to move closer, to a distance of about 1.2 metres, for the same head-and-shoulders shot. At the closer focus distance, the depth of field will be a fairly tight 9.5cm at f/1.4, stretching to 12cm at f/1.8 and shrinking to 8cm at f/1.2.

At the other end of the scale, you’d need to move back to a shooting distance of around three metres when using the Samsung 85mm, which has an effective focal length of about 140mm. Despite the greater shooting distance, the longer focal length of the lens enables a tighter depth of field of just 7cm when shooting at f/1.4.

Ultimately, it’s perfectly possible to tighten depth of field and blur the background effectively when using any of the lenses in this test.

SEE MORE: Best compact system camera: 6 top CSCs go head to head

Smoothly does it
When minimising depth of field, the bokeh, or quality of defocussed areas, becomes important. The ideal is for a lens to produce a smooth and creamy-looking bokeh, with pleasing transitions between focussed and unfocussed areas.

A greater number of diaphragm blades helps to maintain a well-rounded aperture when stopping down a little, which avoids defocussed bright objects taking on noticeable geometric shapes.

Good control over longitudinal chromatic aberrations also pays dividends, as this helps to fend off a type of colour fringing that can’t be corrected, even in cameras that feature automatic removal of lateral chromatic aberrations.

It’s not all about increasing shutter speeds and reducing depth of field, though. High-quality prime lenses often tend to be sharper than most zoom lenses, while also exhibiting less distortion.

That said, this class of lens can be prone to losing sharpness and contrast, as well as producing noticeable vignetting (darkened image corners) towards the wider end of the aperture range.

SEE MORE: 5 things photographers will learn switching from DSLR to mirrorless

Small wonder
One of the biggest selling points of compact system cameras is that they’re physically small, lightweight and easy to carry around with you. These advantages would be nullified if you had to carry big, heavy lenses – but, despite being ‘fast glass’, most of the lenses in this group test are reasonably compact.

The exceptions are the Samsung 85mm f/1.4 and Sony 55mm f/1.8 lenses, which are actually bigger and heavier than some full-frame SLR lenses of similar focal lengths and apertures.

However, most of the lenses in this group test certainly aren’t lightweight when it comes to the price tag, with costs stretching as high as £1,200 for the Panasonic 42.5mm lens.

Let’s take a closer look at the features, build quality and performance of all the contenders, to see how they measure up. But first…

How we test lenses

Our lens tests are based on a two-stage procedure. First, extensive lab tests are carried out, shooting two test charts under carefully controlled lighting conditions.

The results are processed using Imatest Master, so that we can quantify optical performance in terms of sharpness, chromatic aberrations and distortion. Overall quality is assessed at the centre, edge and corners of the images.

For this class of prime lens, we pay particular attention to the image quality at the widest available apertures, as this is a key benefit of a fast prime lens compared with standard zoom lenses.

For real-world testing, we use each of the lenses under widely varying indoor and outdoor lighting conditions. Overall handling is checked, along with the smoothness and precision of control rings and switches.

We also test the speed and accuracy of the lenses’ autofocus systems, complete with operation of full-time manual override where this is available. Ratings are finally given for features, build quality, image quality and value for money.

SEE MORE: How to get the best from your camera lenses

Best prime lens for mirrorless cameras: Fujifilm XF 56mm f/1.2 R

Price: £900 / $1,000
One of the larger and heavier lenses in the group, the XF 56mm feels robust and well-built. The combination of an approximately 85mm effective focal length and a fast f/1.2 aperture makes it potentially perfect for portraiture.

On-board controls comprise an aperture ring with one-third f/stop increments, and a smooth and fluid focus ring that’s also comfortably large. It’s a shame that, unlike in all the other camera and lens combinations on test, full-time manual override isn’t available.

Despite weighing 405g and having a 70mm-diameter barrel, which extends beyond the bottom of the Fujifilm X-E2 we used for testing, the body and lens combination feels well-balanced and entirely natural.

Interior highlights include two ED (Extra-low Dispersion) elements, a double-sided aspherical element, and four convex elements designed to produce even light coverage across the image frame.

Performance
It’s certainly not the sharpest lens in the group, but defocussed areas are particularly smooth, and the transition between focussed and defocussed areas is also very clean.

Contrast is good even at the widest available aperture and, true to the manufacturer’s claims, the lens has minimal vignetting even at f/1.2. Colour fringing can be slightly apparent at f/1.2, but pretty much disappears by the time you hit f/2.8.

There’s only the merest touch of barrel distortion and, overall, image quality is very good indeed. It’s a beautifully built lens, with performance to match.

Features: 4/5
Build Quality: 5/5
Image Quality: 4/5
Value: 4/5

Overall: 4/5

SEE MORE: Best Fuji lens: which to buy next

Best prime lens for mirrorless cameras: Nikon 1 32mm f/1.2

Price: £650 / $720
Thanks to the 2.7x crop factor of the Nikon 1 system, this diminutive 32mm lens has an effective focal length of about 85mm, coupled with a wide available aperture of f/1.2.

It therefore matches the Fujifilm 56mm lens in these respects, although the Nikon is much smaller and little more than half the weight.

Build quality feels pretty solid and there are no switches or other moving parts, apart from the focus ring.

Indeed, it’s the first Nikon 1 lens to feature a manual focus ring, along with SWM (Silent Wave Motor) ultrasonic autofocus. Autofocus isn’t especially fast, but at least it features full-time manual override.

A feature shared with some of Nikon’s upmarket SLR lenses is the Nano Crystal Coating applied to combat ghosting and flare, even when shooting into the light.

However, more in common with other CSC lenses, there’s no rubber weather seal ring on the lens mount, as fitted to most Nikon SLR lenses.

SEE MORE: Best Nikon lenses for DX-format cameras

Performance
Unusually, sharpness peaked at f/2.8 in our tests, but it’s still good at the widest f/1.2 setting, as well as at mid-range apertures, where it’s a pretty close match to the Fujifilm 56mm lens.

The bokeh is pleasant, but not quite as silky-smooth as from most other lenses in the group. Colour fringing is fairly well controlled, but distortion is slightly more noticeable than with most competitors.

Vignetting is remarkably low even when shooting wide open, especially considering it’s such a small lens with such a wide available aperture.

Features: 3/5
Build Quality: 4/5
Image Quality: 3/5
Value: 4/5

Overall: 4/5

SEE MORE: Nikon lenses from A-Z: the ultimate photographer’s guide

Best prime lens for mirrorless cameras: Olympus 25mm f/1.8

Price: £370 / $410
The Olympus 25mm is the smallest and lightest lens here, measuring just 58x42mm and weighing a mere 137g.

Two factors that help to facilitate the diminutive dimensions are that the focal length is a mere 25mm (effectively 50mm on a Micro Four Thirds body), and the widest available aperture is f/1.8 – that’s two-thirds of a stop or a full stop slower respectively than the f/1.4 or f/1.2 lenses in the group.

However, most of the faster lenses are also between two and three times as expensive. Despite its relatively light weight and downmarket price, the Olympus feels strong and satisfyingly well engineered.

As an MSC (Movie & Still Compatible) lens, autofocus is essentially silent. The manual focus ring is rather larger than that of the Nikon 32mm lens, and more comfortable to use, although both operate very smoothly.

Unlike the sibling Olympus 75mm that’s also on test, this one isn’t badged as an ED lens, but it does feature two aspherical glass elements in its design.

There’s also a seven-blade diaphragm that manages to maintain a fairly well-rounded aperture when stopping down a little from f/1.8.

Performance
Despite looking a bit of a poor relation with its widest f/1.8 aperture, the Olympus manages to produce a beautiful bokeh: in our tests, it looked smoother than the effect delivered by the Nikon 32mm, with its wider aperture and longer focal length.

Sharpness is also spectacular, even at f/1.8, although the degree of barrel distortion is a little disappointing.

Features: 3/5
Build Quality: 4/5
Image Quality: 4/5
Value: 4/5

Overall: 4/5

SEE MORE: Olympus cameras: the full and complete range explained

Best prime lens for mirrorless cameras: Olympus ED 75mm f/1.8

Price: £720 / $800
Every inch the big-yet-modestly-sized brother of the Olympus 25mm lens, the 75mm has a similar look and feel.

Again, it’s an MSC lens with clean styling and no switches, just a focus ring as its only moving part. Further similarities include a fully internal focussing system that’s fast and accurate.

Build quality feels solid and robust, even though the lens weighs a mere 305g, just half the weight of the competing Samsung 85mm. Naturally, the Samsung has to produce a bigger image circle, and it’s also two-thirds of a stop faster at f/1.4.

Even so, the Olympus feels a very natural and well-balanced fit on PEN and OM-D bodies, while giving a useful short telephoto focal length, equivalent to 150mm on a full-frame camera.

There’s also an Olympus 45mm f/1.8 that bridges the gap between the 25mm and 75mm lenses in the line-up.

Additional upmarket features compared with the Olympus 25mm include three ED (Extra-low Dispersion) glass elements, and nine diaphragm blades, the latter helping to ensure a particularly well-rounded aperture.

SEE MORE: Best budget cameras 2016: 8 top options tested and rated

Performance
In most respects, performance is extremely similar to the Olympus 25mm lens. Bokeh is delightfully smooth despite the merely modest f/1.8 maximum aperture, while sharpness and contrast are both excellent, even when using the lens wide open.

Again, vignetting is minimal. Where the 25mm produces noticeable barrelling, the 75mm creates a hint of pin-cushion distortion.

Features: 4/5
Build Quality: 4/5
Image Quality: 4/5
Value: 4/5

Overall: 4/5

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