The Sony FE 40mm F2.5 G is a wide normal-length prime lens for Sony Alpha full-frame and APS-C E-mount mirrorless cameras, where it provides a 60mm equivalent focal length.
This new lens boasts a premium weather-sealed construction, physical aperture ring that can be de-clicked, and a focus hold button.
The Sony 40mm F2.5 was launched in March 2021 alongside the FE 24mm F2.8 G and FE 50mm F2.5 G lenses.
It features 9 elements in 9 groups, with one Extra-low dispersion element to reduce chromatic aberrations and color fringing and three aspherical lenses which help to control distortion and spherical aberrations.
There’s a Fluorine-coated front element that makes the lens easier to clean by cutting down on dust, moisture, and fingerprints.
This lens boasts a dust- and splash-proof structure and has a minimum focusing distance of 28cm with a maximum magnification of 0.20x when auto-focusing.
It has a rounded 7-blade diaphragm which creates an attractive blur to out-of-focus areas of the image and an internal focusing mechanism which means the lens barrel doesn’t move.
There is a XD Linear Motor AF system with two separate focusing motors for fast, quiet and precise auto-focusing, while the focusing ring provides fine manual focus control.
A traditional aperture ring runs from f/2.5 to f/22 in third-stop increments with an Auto setting also available for camera-based aperture selection.
The Sony FE 40mm F2.5 G lens is available now priced at £629 / $599 in the UK and USA, respectively.
Ease of Use
Weighing in at 173g, the all-metal bodied Sony FE 40mm F2.5 G is very light for such a premium full-frame lens.
Its overall size and weight is well-suited to a camera like the Sony A7R IV that we tested it with, as shown in the product photos. Even with the supplied hood attached, it is still very discrete.
It measures 68mm x 45mm, making it identical in size to the Sony FE 24mm F2.8 lens that we recently reviewed.
The novel 40mm focal length takes a little while to get used to, falling between the more “normal” 35mm and 50mm focal lengths that photographers are more used to, but it quickly loses any real significance after you’ve used it for a while.
It does mean that the Sony FE 40mm F2.5 G doesn’t have too many direct rivals. There’s the Voigtlander 40mm f1.2 Nokton Aspherical, but that’s a strictly manual-focus lens, the pricey Zeiss Batis 40mm f/2 and the huge and heavy Sigma 40mm F1.4 DG HSM.
The Sigma 35mm F2 DG DN and Sigma 45mm F2.8 DG DN take a similar design approach to the Sony 40mm but offer a slightly wider and narrower angle of view respectively.
Build quality is excellent, far exceeding what you might expect from a mid-range prime lens, although it’s not quite as good as the superlative Sigma 35mm F2 DG DN and 45mm F2.8 DG DN lenses.
It incorporates a metal mount and lens barrel with metal focus and aperture rings – even the lens hood is metal (all made from aluminium). The focal length and aperture markings are engraved rather than painted on.
It also boasts a dust- and moisture-sealed design to support shooting in more inclement conditions.
The Sony FE 40mm F2.5 G lens accepts 49mm filters via metal threads on the front of the lens.
The lens doesn’t feature built-in optical image stabilisation, relying instead on the camera body’s stabilisation system.
The Sony FE 40mm F2.5 G lens has a rather narrow, ridged motor-assisted focus ring that is very nicely damped. Manual focusing is possible by using the focus mode switch to toggle between AF and MF.
As the the focus ring is not mechanically coupled, there are no hard stops at either end of the range, making it a little more difficult to set focus at infinity. Polariser users should be pleased that the 49mm filter thread doesn’t rotate on focus.
The manual focusing ring is positioned very close to the end of the lens, but the recessed, tapered design of the well-thought-out lens hood means that it doesn’t interfere with the operation of the MF ring when it is fitted.
The Sony FE 40mm F2.5 G lens utilises a XD Linear Motor system that uses two separate focusing motors which produces silent, smooth amd very fast auto-focusing, making it well-suited to shooting both stills and video, with the overall lens length remaining constant during focusing.
When it comes to auto-focusing, it proved to be a very quick performer on the Sony A7R IV camera that we tested it with.
We found it to be marginally faster and quieter than the comparable Sigma 35mm F2 DG DN lens.
We didn’t experience any “hunting”, either in good or bad light, with the lens accurately focusing all of the time.
Sony’s near flawless Eye AF works perfectly with this lens, quickly locking onto and tracking the subject’s eye despite the wide-angle view, and as you’d expect, it fully supports Sony’s DMF and AF+MF shooting modes.
The Sony FE 40mm F2.5 G lens features an aperture ring that has 1/3EV stops ranging from f/2.5 to f/22 and an Auto setting if you prefer to set the aperture via the camera body.
There’s also a Click switch on the lens barrel that lets you de-click it for silent operation during movie recording, something that the Sigma 35mm F2 DG DN notably lacks.
Sony have even found room for a small, configurable focus hold button which as the name suggests locks the focus at the current setting.
The 40mm focal length provides an angle of view of 57 degrees on a 35mm full-frame camera.
Chromatic aberrations, typically seen as blue or purple fringes along contrasty edges, were somewhat apparent in our test shots, appearing in very high contrast areas. The example below shows the worst-case scenario.
With the lens set to its maximum aperture of f/2.5, there is obvious light fall-off in the corners, requiring you to stop down by at least 3 f-stops to completely prevent it.
There’s not much barrel distortion evident in either the RAW or JPG files – the Sony Alpha A7R IV automatically and successfully applies corrections to the JPG files.
Sunstars and Flare
The Sony FE 40mm F2.5 G is capable of producing nice sunstars when stopped-down to f/16 and f/22, as shown below, although it is a little prone to flare.
The Sony FE 40mm F2.5 G is not really a macro lens, offering a close minimum focusing distance of 25cm when manually focusing and 28cm when auto-focusing, and a maximum magnification of 0.23x in MF and 0.20x in AF. The following examples demonstrate how close you can get to your subject.
Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc.
In the FE 40mm F2.5 G lens, Sony have employed an iris diaphragm with 7 rounded blades, which has resulted in appealing bokeh for what is after all a moderately wide-angle lens.
We do realise, however, that bokeh evaluation is subjective, so we’ve included several examples below for your perusal, all shot wide-open at f/2.5.
In order to show you how sharp the Sony FE 40mm F2.5 G lens is, we are providing 100% crops on the following page.