In summary
A new standard zoom lens for Sony’s full-frame E-mount cameras, offering a wider zoom range and constant f/4 maximum aperture in a compact design.
The Sony FE 20-70mm f/4 G is one of the more interesting standard-range zoom lenses to appear in recent times and it’s well worth a look for anyone who wants a wider reach than the standard 24-70mm or 24-105mm zooms.
Full review
Announced in mid-January, 2023, the FE 20-70mm f/4 G lens is targeted at owners of Sony’s full-frame mirrorless cameras who want a versatile zoom range in a relatively fast, lightweight and compact form factor. Designed for a wide range of creators this lens can be used for recording stills and video clips and will suit both serious vloggers and photo enthusiasts involved in portraiture, street photography and shooting landscapes and cityscapes. It is also versatile enough for travellers who want slightly more versatility than the regular 24-70mm zoom range.
Angled view of the FE 20-70mm f/4 G lens without the supplied lens hood. (Source: Sony.)
The optical design of this lens consists of 16 elements in 13 groups and includes two AA (advanced aspherical) elements, one aspherical element, three ED (Extra-low Dispersion) glass elements and one ED aspherical element, which are arranged in a configuration (shown below) that simultaneously corrects chromatic and spherical aberrations. Optimised coatings add high flare and ghosting resistance to preserve image contrast and clarity.
This diagram shows the arrangement of the optical elements in the FE 20-70mm f/4 G lens. (Source: Sony.)
A nine-bladed iris diaphragm produces natural-looking bokeh, while the minimum focus distance of 30 cm at 20mm and 25 cm at 70mm allow scope for shooting close-ups, while making it easy for photographers to shoot subjects from a variety of different angles. The inner barrel extends by approximately 40 cm when you zoom from 20mm to 70mm.
Autofocusing is driven by two of Sony’s latest XD (extreme dynamic) linear motors, which move the focus group approximately 60% faster than in previous models, providing a fast, quiet and low-vibration focus drive. Improved tracking performance enables moving subjects to be tracked with consistent reliability and precision, even at high frame rates, ensuring smooth video recordings.
This diagram shows the two XD linear motors used to provide high thrust for fast, quiet, smooth focusing. (Source: Sony.)
Sony has utilised the latest lens technology to reduce focus breathing, as well as focus and axial shift when zooming, while a newly developed aperture unit dramatically reduces noise and vibration. The lens boasts a Linear Response MF that ensures the focus ring responds directly and linearly to subtle controls. An independent aperture ring provides direct aperture control.
The review lens was not supplied with the bundled ALC-SH174 lens hood or the soft carrying bag. They should be included with the lens at point of purchase.
Who’s it For?
Sony’s G-class lenses are designed and constructed to balance manufacturing costs and performance quality and, as a result, they should appeal to most enthusiasts. As mentioned above, the Sony FE 20-70mm f/4 G should be of particular interest to owners Sony’s full-frame cameras who want some extra reach at the wide end of an otherwise standard zoom lens. There’s no point using it on Sony’s APS-C cameras, which will crop away much of the frame.
Videographers will find the focus breathing compensation support of at least equal interest, especially when the lens is used with a compatible Sony camera. The easy-to-access Click On/Off switch will also be attractive as it gives them a clickless aperture option.
This diagram shows the positions of the weather-resistant seals in the lens barrel. (Source: Sony.)
While the lens is specified as having ‘a dust and moisture resistant design’, it isn’t rated to a specific IP standard. Outdoor enthusiasts should take a fairly cautious approach to the weatherproofing but they will certainly appreciate the combination of decent imaging/video performance with the compact size and low weight of the lens itself.
Build and Ergonomics
Build quality is generally excellent, as expected for a G-class lens. Although the lens barrels are made of industrial plastics, they’re on a metal mount which gives additional stability. In use, this lens feels solid, with no flexing in the inner barrel, even when fully extended.
The front element is approximately 50 mm in diameter and surrounded by a stepped plastic border that is partially ribbed and carries the name of the lens and the filter thread diameter (72 mm). The lens surface is fluorine coated to repel moisture and dust particles. A bayonet mounting for the lens hood surrounds its outer edge.
The focusing ring is located roughly 12 mm behind the front rim of the lens. It’s 15 mm wide and covered in ribbed, rubber-like cladding. This ring turns through a full circle when the camera’s power is off but operates smoothly in manual focus mode.
Immediately behind the focusing ring is a fixed, 15 mm wide section of the outer barrel that carries the two focus hold buttons and the AF/MF switch. Behind it lies the 17 mm wide zoom ring, which has ribbed, rubber-like cladding covering a 13 mm wide band around its leading edge. The trailing edge of the ring is stamped with settings for the 20mm, 24mm, 28mm, 35mm, 50mm and 70mm focal lengths.
The aperture ring is located directly behind the zoom ring. It’s 10 mm wide and carries markings in full f-stop increments between f/4 and f/22, with an ‘A’ position at the f/22 end for setting auto aperture selection. Intermediate marks between the f-stops denote 1/3 EV increments.
The Click On/Off and iris lock switches are located on the 10 mm wide sloping section of the outer barrel aft of the aperture ring, which leads on to a straight 10 mm wide section of the barrel that ends in the chromed metal lens mount. Inside the mount are ten gold-plated contacts for passing signals between the lens and the camera body.
Performance
Our Imatest tests were carried out with the lens on the Sony α7C II camera, which is reviewed separately. They showed the review lens to be an impressive performer, with measured resolution in the centre of the frame in JPEG files slightly exceeding expectations for the camera’s sensor and the mid-range and edge measurements falling only a little below them.
RAW files recorded simultaneously produced even better results, with only the measurements taken near the edge of the frame failing to meet expectations. The graph below shows the results of our Imatest tests, based on JPEG files taken at each aperture and focal length setting.
Sony cameras automatically correct most common aberrations so our vignetting and distortion tests were carried out on uncorrected raw files. For chromatic aberration, we looked at the Imatest results for uncorrected raw files and found them to straddle the borderline between ‘negligible’ and ‘low’ CA, whereas the JPEG files showed almost complete correction. For most users, chromatic aberration would therefore be a minor issue.
The lateral chromatic aberration results for JPEG files showed in-camera corrections were highly effective.
In contrast, ARW.RAW files showed noticeable vignetting, particularly at 20mm with the f/4 maximum aperture. It’s less noticeable with the other focal lengths, although still detectable at apertures between f/4 and f/5.6 and virtually absent in JPEGs, which suggests fairly vigorous processing.
Similarly, ARW.RAW files recorded at the 20mm focal length showed strong – and very noticeable – barrel distortions. Most distortions had disappeared by between 28mm and 35mm, shifting to visible (though not excessive) pincushion distortion by 70mm. In-camera auto-correction eliminates these distortions from JPEG files, save for a trace of residual barrel distortion at 20mm.
Bokeh is quite good for a lens of this type, since standard-range zoom lenses tend to perform quite poorly in this area. However, a lot depends upon the background lighting.
We found some outlining of bright highlights in shots taken with the 70mm focal length at f/4 and they became a little more ovoid near the edges of the frame. Stopping down to f/8 returned their circular shape but reduced the background blurring. With evenly-lit backgrounds, we found background blurring to be smooth enough to justify shooting close-ups with any focal length setting.
The review lens produced some nice, 18-pointed sunstars at f/22 with all the focal lengths we tested. We found a few flare artefacts at 35mm, 50mm and 70mm and very slight veiling flare at the 70mm position. Otherwise, the lens handled backlit scenes very competently.
Without the bundled lens hood it was difficult to quantify flare and ghosting performance. However, we found flare was seldom an issue with the review lens, although it could be forced to flare if you shoot directly into the sun – which is not recommended. We found occasional instances of slight veiling flare and a few small flare artefacts, but careful framing of shots would easily eliminate them so they aren’t a real problem.
Conclusion
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SPECS
Picture angle: 34 to 94 degrees diagonal
Minimum aperture: f/22
Lens construction: 16 elements in 13 groups (including 2 XA, 2 ED and 2 Super ED glass elements)
Lens mount: Sony E-mount
Diaphragm Blades: 9 (circular aperture)
Weather resistance: Dust and weather-resistant sealing in 9 locations
Focus drive: Four XD (extreme dynamic) Linear Motors with floating focus mechanism
Stabilisation: No
Minimum focus: 30 cm at 20mm and 25 cm at 70mm
Maximum magnification: 0.39x
Filter size: 72 mm
Dimensions (Diameter x L): 78.7 x 99 mm
Weight: 488 grams
Standard Accessories: ALC-F82S front cap, ALC-R1EM rear cap, ALC-SH174 petal-shaped lens hood, soft case.
Distributor: Sony Australia
TESTS
Based on JPEG files taken with the Sony α7C II camera.
Based on ARW.RAW recorded simultaneously and converted into 16-bit format with Adobe Camera Raw.
SAMPLES
Vignetting at 20mm.
Vignetting at 35mm.
Vignetting at 70mm.
Rectilinear distortion at 20mm.
Rectilinear distortion at 35mm.
Rectilinear distortion at 70mm.
20mm focal length, ISO 100, 1/320 second at f/11.
70mm focal length, ISO 100, 1/320 second at f/11.
Close-up at 20mm focal length, f/4, ISO 100, 1/400 second.
Close-up at 35mm focal length, f/4, ISO 100, 1/500 second.
Close-up at 70mm focal length, f/4, ISO 100, 1/500 second.
Bokeh in close-up at 70mm, f/4.5, ISO 100, 1/100 second.
Sunstar at 20mm focal length, ISO 100, 1/80 second at f/22.
Sunstar at 35mm focal length, ISO 100, 1/60 second at f/22.
Sunstar at 50mm focal length, ISO 100, 1/80 second at f/22.
Sunstar at 70mm focal length, ISO 100, 1/160 second at f/22.
Backlit scene; 70mm focal length, ISO 100, 1/100 second at f/5.6.
Uncorrected raw file showing inherent barrel distortion; 20mm focal length, ISO 100, 1/60 second at f/9.
The same image recorded as a JPEG file with in-camera corrections applied.
20mm focal length, ISO 800, 1/30 second at f/8.
70mm focal length, ISO 100, 1/80 second at f/11.
20mm focal length, ISO 100, 1/40 second at f/11.
70mm focal length; ISO 200, 1/80 second at f/13.
70mm focal length; ISO 100, 1/100 second at f/11.
70mm focal length, ISO 100, 1/200 second at f/4.5.
Crop from the above image magnified to 100%.
35mm focal length; ISO 100, 1/250 second at f/5.6.
70mm focal length, ISO 100, 1/1600 second at f/4.
70mm focal length, ISO 500, 1/80 second at f/9.
53mm focal length, ISO 640, 1/125 second at f/4.
70mm focal length, ISO 100, 1/100 second at f/4.5.
70mm focal length, ISO 100, 1/160 second at f/5.6.
70mm focal length; ISO 100, 1/80 second at f/11.
70mm focal length; ISO 250, 1/60 second at f/11.
Additional image samples can be found with our review of the Sony α7C II camera.
Rating
RRP: AU$1399
- Build: 9.0
- Handling: 8.9
- Image quality: 9.0
- Autofocusing: 9.0
- Versatility: 9.0
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