First impressions of the Sony FE 50mm F1.2 GM
 |
It seems that every camera company is flexing its optical muscles these days to churn out F1.2 lenses. Sony, not one to be left behind, just released its first F1.2 prime, the FE 50mm F1.2 GM. One can’t help but ponder if Sony made this lens, at least in part, to dispel the myth that the smaller lens mount diameter – compared to its mirrorless peers – makes such fast lenses impossible (Sony claims F0.63 E-mount lenses can be made, but don’t make business sense).
Either way, while the Planar T* FE 50mm F1.4 ZA optic was impressive in its own right, offering a very flat field of focus and minimal aberrations, the 50mm F1.2 appears to exceed it in nearly every respect.
Click through for a closer look.
Size and weight
 |
The FE 50mm F1.2 GM is surprisingly compact and lightweight for what it offers. Next to the Planar T* 50mm F1.4 ZA, it’s nearly the same size and at 778g weighs exactly the same, despite offering half a stop more light gathering and shallow depth-of-field capability. Both lenses are exactly the same length: 108mm. The F1.2 GM has a slightly larger diameter, with the largest section of its barrel measuring 87mm compared to 83.5mm for the F1.4 ZA. This can be explained by the approximately 36% increase in surface area required for an F1.2 aperture compared to F1.4. Still, the filter diameter is a modest 72mm.
Mount each lens on a camera body, close your eyes, and you won’t be able to tell which lens is attached. Well, save for the nicer rubberized manual focus ring on the F1.2 GM.
The Sony optic is the smallest and lightest of its competitors, weighing 18% less than Canon’s RF 50mm F1.2 and 30% less (and 30% shorter) than Nikon’s 50mm F1.2 S.
Build quality and sealing
 |
Despite its compact size, the 50mm F1.2 GM feels very well-built. Similar to other lenses in the GM-series, it’s rated as ‘dust and moisture resistant’, with seals around all buttons and rings. A rubber gasket around the mount should help protect against moisture and other elements entering the camera body. Sony says that hybrid metal and engineering plastic has been used for durability and to reduce the weight of the lens. Finally, a fluorine coating on the front element should make water, oils, fingerprints and dirt easy to clean off.
External controls
 |
The FE 50mm F1.2 GM lens offers a number of external controls. A focus mode switch allows you to quickly switch between auto and manual focus. Two focus hold buttons can be customized to any function available to all other custom buttons on the camera body. The manual focus ring has a nice rubberized texture that makes it easy to grasp and that also differentiates it from the aperture ring. The focus ring offers a linear focus response for intuitive focus pulls in video and stills…
External controls (continued)
 |
The aperture ring has a texture similar to the lens barrel but with ‘teeth’ to make it easy to grasp and turn. F-stops are marked in 1/3 EV steps. The aperture ring can be ‘clicked’ or ‘de-clicked’, with the latter setting making it easier to smoothly change the aperture if you wish to vary the depth-of-field while shooting video.
Optical design
 |
The optical construction comprises 14 elements in 10 groups. Three extreme aspherical (XA) elements – shown here in orange – help minimize aberrations and reduce the overall size of the optics. These XA elements also play a role in maintaining high resolution across the frame at wide apertures.
Bokeh
 |
Enhanced surface precision of the molds used to create those XA elements in the last slide helps ensure smooth bokeh. Pictured at the top left in this image (courtesy of Sony) is a conventional aspherical lens surface, leading to an undesirable circle of confusion (top right). At the bottom left is a surface trace of one of Sony’s XA lens surfaces with 0.01µm surface precision, creating a clean circle of confusion (bottom right) and generally pleasing bokeh.
Sony claims that spherical aberration has been carefully controlled at the design and manufacturing stages for smooth foreground and background bokeh, and the comparative images Sony showed us against competitors were convincing, though we’ll reserve final judgement for after our own testing.
Bokeh
 |
An 11-bladed aperture ensures circular out-of-focus highlights even as you stop down. In the image above you can see perfectly circular discs even after stopping the lens down 1.7 stops, which would be difficult for a lens with 9 or 10 aperture blades to do. Though there are many other factors that contribute to pleasing bokeh, this should help the F1.2 GM pleasantly render out of focus lights and produce smoother, more Gaussian bokeh.
There’s some mechanical vignetting that leads to cat’s eye effect wide open as you can see on the left, but it mostly disappears as you stop down to F1.8 and is completely gone by F2, as you see on the right.
Sharpness
 |
MTF traces provided by Sony suggest impressive performance wide open (leftmost MTF graph), with over 90% contrast retained for higher resolution 30 lp/mm detail (green) at the center of the frame continuing out at least 6mm from the center of the imaging circle. Meanwhile, this 30 lp/mm trace, indicative of lens’ sharpness, never dips below 60% anywhere in the frame, typically hovering nearer to 70% at image peripheries.
The fact that the sagittal and tangential traces generally closely follow each other indicate that astigmatism is well-controlled, which suggests that bokeh should have a pleasing rendering, which bears out in our initial impressions.
A quick note on reading these graphs: sagittal or radial traces are solid while tangential traces are dotted. Orange traces are for 10 lp/mm detail, often indicative of lens’ contrast performance. The higher the traces, the better.
Sharpness
 |
What does sharpness at F1.2 look like in real-world shooting? Have a look at this image at 100%. Depth of field is razor thin at F1.2, but Sony’s Eye AF is generally accurate enough, and AF speeds with this lens are responsive enough, that hit rates are high. Which brings us to…
Autofocus
 |
Two independent floating focus groups allow for close focusing distances, and are driven by four ‘extreme dynamic’ linear motors (two per focus group). We’re told by Sony that these linear motors are very efficient at generating linear motion, as they don’t require any translation of rotational motion to linear motion, as ring-type and stepper motors do. The results speak for themselves, both in this demonstration video from Sony and in our own independent tests that confirm the 50mm F1.2 GM is the fastest-to-focus lens of its type. We measure only a mere 0.65s for the lens to rack from minimum focus distance (0.4m) to infinity, and 0.5s to rack from 0.7m – still a very close working distance for the 50mm focal length – to infinity.
In comparison, the tiny FE 35mm F1.8 optic takes a similar 0.5s to rack from its minimum focus distance to infinity, while the Nikkor 35mm F1.8 S takes a bit over 1s to do so. And those lenses are more than a stop slower.
The minimum focus distance of 0.4m (15.8″) yields a maximum magnification of 0.17x. Unfortunately, focus breathing, or a change in magnification with focus distance, is pretty significant and might be an issue for video shooters.
Longitudinal chromatic aberration
 |
When it comes to fast lenses of this type, longitudinal chromatic aberration, abbreviated simply as LoCA, is one of the major aberrations we tend to worry about, especially as it tends to be hard to remove in post-processing and can be distracting. It shows up typically as magenta and green fringing in front of and behind the focus plane, respectively, around high contrast objects in the image.
There is almost no such fringing to speak of with the FE 50mm F1.2 GM, not even after drastic contrast adjustments that would exaggerate any LoCA present in the image, as we have done above (+45 in Adobe Camera Raw).
Sony tells us the lack of this aberration is due in part to the XA elements, as well as the use of the latest advanced simulation technology.
Flare, ghosting and sunstars
 |
Sony’s ‘Nano AR (anti-reflective) II’ coating helps reduce flare as well as the appearance of distracting ‘ghosts’, both caused by reflections off of the internal elements. Nano AR II was developed specifically for application to large optical elements with highly curved surfaces, such as the XA elements increasingly found in Sony’s lenses.
The image above was shot by pointing the camera at the sun and angling it in such a way as to introduce as much flare and ghosting as possible. Results are impressive: there is very little loss of contrast, and the 2 or 3 visible ghosts (the purple and blue circles at upper right) aren’t too distracting or unsightly, instead appearing rather diffuse.
The 11-blade aperture produces 22-point sunstars with point light sources in the frame, if you stop the aperture down (pictured here is F11).
Lateral chromatic aberration
 |
As is the case with many modern, well corrected lenses, lateral chromatic aberration, which shows up as magenta and cyan or green fringing at image peripheries that does not improve significantly upon stopping down, isn’t much of an issue, particularly because it’s taken care of digitally. Above, the left half of the image is identical to the right half, except that it’s had any lateral CA removed using the included profile embedded in Sony Raw files (processed here in Capture One). Noticeable mostly at high contrast edges, lateral CA simply isn’t an issue after it’s been removed, either in your favorite Raw converter, or in-camera by selecting ‘Auto’ for ‘Chromatic Aberration Comp’ under the ‘Lens Comp’ option in the camera menu.
This particular example is a crop from an extreme corner of the frame, so even if you leave lateral CA uncorrected – which you shouldn’t – this level of aberration is nothing to concern yourself over.
Distortion
 |
We don’t tend to worry about distortion on 50mm prime lenses, but we do find it interesting that there is a noticeable amount of pincushion distortion if you go looking for it by comparing uncorrected vs. corrected images. The left half of this image is corrected while the right half is not; note the slight inward bend of the right edge of the stone wall on the right compared to the straight edge on the left. And the magnification of the rectangular tiles on the left relative to those on right, particularly obvious if you look at the center of the image.
These artifacts are all due to distortion correction having been applied to the left half of the above image only. For whatever reason, Sony has chosen to leave some optical distortion behind in the optical formula for, albeit very easy, digital correction afterwards. It’s worth noting that, for now, Adobe Camera Raw allows for no such provision for distortion correction – not until Adobe has profiled this particular lens – while Capture One honors the built-in manufacturer distortion correction profile included in Raws shot with the 50mm F1.2 GM. This is one of the reasons we have chosen to include some Capture One conversions in our gallery of this lens.
Price and availability
 |
The FE 50mm F1.2 GM is Sony’s 60th E-mount lens, its 40th full-frame E-mount lens, introduced right around the 5th anniversary of the introduction of Sony’s first GM lenses. From our initial testing we’d venture to say the FE 50mm F1.2 GM is probably one of Sony’s sharpest, fastest to focus, and most aberration free primes
Expect to see it in the wild mid-May 2021, at an MSRP price of $ 1999 USD.
See our Sony FE 50mm F1.2 GM Sample Gallery
Articles: Digital Photography Review (dpreview.com)