Lens review

Sony FE 20-70 mm f/4 G

17 January 2023
Maciej Latałło

3. Build quality

Currently the Sony FE 20-70 mm f/4 G has just one rival and it s the Panasonic, mentioned by us in the introduction.  The following chart presents a comparison between basic parameters of these two lenses. The Panasonic is a bit smaller and it weighs less; small wonder, its focal length range is a bit narrower and its aperture – a bit slower.

In the photo below the Sony FE 20-70 mm f/4 G is positioned between the Nikkor AF-S 24-70 mm f/2.8G ED and the Olympus M.Zuiko 12-40 mm f/2.8 ED PRO.

Sony FE 20-70 mm f/4 G - Build quality

The tested lens starts with a metal mount surrounding a contact plate and a 33×24 mm frame made of plastics. A rear element, 28 mm in diameter, is positioned inside and it doesn't move. Its casing almost touches the frame at 20 mm and the element hides almost 3 cm deep when you pass to the 70 mm focal length. That movement reveals an inner tube that is well blackened and matted.

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Sony FE 20-70 mm f/4 G - Build quality

The proper body of the Sony 20-70 mm starts with an immobile black ring made of plastics which diameter increases as you move further from the mount. On the ring you can find the name and basic parameters of the lens along with a whte dot, making an alignment with a camera easier, the mount type (E-mount), the IRIS LOCK switch that blocks the aperture ring, the CLICK ON/OFF switch that controls the aperture ring mode, and information that the lens was produced in Thailand.

The next ring allows you to change the aperture of the lens. It is 9 mm wide and half of its surface is occupied by rubber ribbing to improve your grip. It can move every 1/3 EV step or you can declick it. It also can be blocked in the A position – then the aperture is controlled by the camera.

Sony FE 20-70 mm f/4 G - Build quality

Then you see two other rings – the first one is narrow and immobile, the other 19 mm wide. The second one is a zoom ring, most of its surface covered by rubber ribbing under which you can find focal length values at 20, 24, 28, 35, 50, and 70 mm. The ring moves with proper, even resistance.

Another ring that doesn't move features an inscription 'Sony' and the G series mark, along with two programmable Focus Lock buttons and an AF/MF switch.

Sony FE 20-70 mm f/4 G - Build quality

Further on you find a manual focus ring, 16 mm wide, completely covered by rubber ribs. It is a focus-by-wire construction that moves with proper resistance. Its focus throw amounts to an angle of about 140 deg, a sensible value for parameters, offered by this lens.

The front element is slightly convex, 52 mm in diameter, surrounded by a part of the barrel with the name and basic parameters of the lens along with a non-rotating filter, 72 mm in diameter, and a hood mount.

The whole front system extends on an a homogeneous tube made of plastics when you pass from 20 mm to 70 mm, increasing the length of the lens by 41 mm.

Sony FE 20-70 mm f/4 G - Build quality

When it comes to the optical construction you deal here with 16 elements positioned in 13 groups. As it befits a lens with very original parameters, the producers weren't skimpy with special parts. As many as three elements are made of low dispersion ED glass, one is made of ED glass but is also aspherical in shape, three other elements are aspherical, two among them being of AA type. Inside you can also find a round aperture with nine blades which can be closed down to f/22 at the maximum.

Buyers get in the box with the lens: both caps, a petal-type hood and a soft pouch.

Sony FE 20-70 mm f/4 G - Build quality