Sony FE 20-70mm f/4G: Appealing Zoom Range, How Good Will It Be?
Related: distortion, fantasy MTF, focus breathing, focusing, optics, Sony, Sony FE, Sony FE 20-70mm f/4 G, Sony Lenses
I’ll be testing the new Sony FE 20-70mm f/4 G just as soon as I can get hold of one. Gotta love that zoom range, highly appealing.
Note the sheer number of advance features in the lens as compared to lenses only half a decade back—see the full description further below. An engineering marvel, including those radically fast Sony AF motors, four of them, allowing up to 30 fps shooting.
Makes me wonder how viable the Sigma lens offerings are these days. There are few reasons left to consider non-Sony AF lenses on Sony.
Get Sony FE 20-70mm f/4 G at B&H Photo starting Jan 18 7 AM Pacific...
The use of the f/4 aperture increases the odds that performance will be reasonably good across the zoom range; f/2.8 would have been far too challenging across that wide zoom range.
I am not enthused about the stated design goals, but it might turn out well for landscape and focus stacking given that some of the design traits are ideal for landscape also:
Designed to accommodate new trends in shooting styles popular among vloggers and content creators...
...effectively eliminates focus breathing, focus shift, and axial shift to prevent unwanted movements and angle of view variations during movie recording.
What Sony means by “axial shift” is unclear, but it might refer to the outer-zone focus shift resulting in a change in focal length with stopping down, which I have previously deemed aperture breathing.
Sharpness
What I like to see in a lens is (a) no focus shift, (b) minimal field curvature, (c) edge-to-edge sharpness. This is what the Voigtlander APO lenses give me (a bit of focus shift aside), and what zooms rarely if ever deliver in all three aspects. And it is why the Sony FE 24-70mm f/2.8 GM II was a big disappointment.
diffraction-free computed fantasy MTF eg impossible at f/8
Lens performance is likely to be strong, but with a huge caveat—distortion and the resulting sharpness losses from distortion correction. Thus it might be quite weak even in the face of a strong MTF chart.
In my experience, the fantasy MTF charts from Sony have invariably failed to match what real lenses actually deliver, so claims of high performance need to be met with some skepticism.
The only company with credible MTF charts (measured charts, multiple apertures, white light) was/is Zeiss. That is, credibly representing the performance you will actually see in a real lens. I’ve personally seen how it is done as well. But even with Zeiss there is variation, though much less so with the Zeiss Otus line. Leica does a nice job on MTF charts in having 3 apertures, but AFAIK Leica does not measure MTF with real lenses, or even account from losses from ray angle with M lenses, a gross distortion of reality, so poor credibility there.
As a rule Sony (and most brand) MTF charts fail to describe the performance of actual lenses you can buy, being wildly optimistic given manufacturing challenges. Worse, they mislead by showing optical performance without accounting for distortion correction, which can greatly reduce micro contrast by stretching pixels. Since Sony does not publish distortion charts (why?!), I can conclude nothing about the potential lens performance from the MTF charts.
| Focal length: | 20-70mm (nominal) |
| Aperture range: | f/4 - f/22 |
| Focusing range: | 8.3in = 21cm |
| Angle of view: | 94° - 34° |
| Number of elements/groups: | 16 elements in 13 groups |
| Diaphragm: | 11 blades, rounded |
| Magnification: | 0.39X = 1:2.56 |
| Filter thread: | 72mm |
| Weight (as weighed): | 17.2 oz = 488g (nominal) |
| Dimensions: | Approx. 3.1 X 3.9" (78.7 X 99mm) |
| Street price: | about $1098 |
| Supplied with: | Front Lens Cap |
Description
From ultra-wide 20 mm to 70 mm
With an unprecedented2 ultra-wide 20 mm to short-telephoto 70 mm zoom range, this versatile lens is an excellent choice for a wide range of movie and still subjects. The ultra-wide 20 mm end of the zoom range maintains a wide angle of view when shooting movies with a 16:9 or 2.35:1 aspect ratio that reduces view angle.
Outstanding G Lens image quality
With two AA (advanced aspherical) elements, one aspherical element, three ED (Extra-low Dispersion) glass elements, and one ED aspherical element, this state-of-the-art lens design corrects both chromatic and spherical aberration for high optical performance right out to the image edges, from ultra-wide 20 mm to 70 mm.
Excellent close-up performance
AA (advanced aspherical) elements help to achieve a minimum focus distance of 0.3 meters (wide) to 0.25 meters (telephoto) when using AF, and 0.25 throughout the zoom range when focusing manually. Maximum magnification is 0.39x for detailed close-ups. Close focus makes it easy to maneuver around small subjects to find the idea angle.
Constant F4 maximum aperture
A constant F4 maximum aperture offers greater flexibility in choosing apertures at any focal length. The selected aperture remains constant throughout the zoom range. There is no need to use extreme ISO settings at the telephoto end of the range, and high shutter speeds can be used as needed to achieve the desired effect.
Peak AF performance for stills and movies
Two XD (extreme dynamic) Linear Motors achieve fast, quiet, smooth focus drive with up to 60% higher AF speed3 and up to two times3 better performance while tracking3 for reliable, precise tracking. Moving subjects are reliably tracked when shooting continuous stills at up to 30 fps4, and high-frame-rate movie capture is smooth.
Compact, lightweight, mobile design
This compact, lightweight lens combines state-of-the-art optical design with Sony’s high-thrust XD (extreme dynamic) Linear Motor technology. Used with a compact mirrorless body, it can deliver superb image quality in any situation at focal lengths from ultra-wide to short telephoto. A great choice for shooting with minimum gear.
Refined movie imagery
Advanced technology reduces focus breathing as well as focus and axial shift when zooming so that distracting image shifts are minimised. XD Linear Motors and a newly developed aperture unit dramatically reduce noise and vibration when shooting movies. The breathing compensation function provided in compatible α series bodies5 is also supported.
Aperture ring with click ON/OFF switch
An independent aperture ring offers direct, intuitive aperture control. A click ON/OFF switch allows the aperture click stops to be turned off when smooth, seamless operation is required.
Active Mode supports ultra-wide images
Active Mode6 image stabilisation in α series cameras works effectively at the ultra-wide 20 mm end of the zoom range, providing excellent image stabilisation performance while maintaining a wide angle of view. This can be particularly useful for shooting smooth, stable handheld footage while walking.
Focus hold buttons and focus mode switch
Customisable focus hold buttons are provided in two locations for easy access and control. Other functions can be assigned to the focus hold button from the body menus to match shooting needs. A focus mode switch makes it possible to switch between autofocus and manual focus on the fly, to quickly adapt to changing shooting conditions.
Dust and moisture resistant design
A dust and moisture resistant design7 provides extra reliability for outdoor use in challenging conditions.
Fluorine front element coating
The front lens element features a fluorine coating that repels fingerprints, dust, water, oil, and other contaminants, while making it easier to wipe off any contaminants that do become attached to the lens surface.
Summary
A groundbreaking standard zoom lens for everyday use, the ultra-wide Sony FE 20-70mm f/4 G spans a popular and versatile range of focal lengths in a compact and lightweight form. Designed to accommodate new trends in shooting styles popular among vloggers and content creators, this ultra-wide to portrait-length zoom provides excellent edge-to-edge sharpness and outstanding image quality for all your imaging needs. Offering an expansive field of view to suit selfie, landscape, cityscape, and other wide-angle applications, this lens also offers fast, precise, and quiet autofocus performance as well as excellent close-up performance at all focal lengths.
G Lens image quality
- Constant f/4 maximum aperture maintains consistent illumination throughout the entire zoom range.
- Three ED elements, two AA elements, one ED aspherical element, and one standard aspherical element to effectively eliminate chromatic and spherical aberrations while also rendering excellent edge-to-edge sharpness and color fidelity.
- Rounded 9-blade aperture provides deep, soft bokeh.
Video and autofocus improvements:
- Two XD (extreme dynamic) linear motors provide smooth, silent, and precise autofocus performance as well as improved tracking performance for photos and videos.
- Internal focusing system maintains the overall length of the lens and does not rotate the lens barrel while focusing, enhancing the use of circular polarizers and variable ND filters.
- Updated optical design effectively eliminates focus breathing, focus shift, and axial shift to prevent unwanted movements and angle of view variations during movie recording.
- Aperture ring with On/Off click switch and iris lock switch prevents the aperture ring from being accidentally moved between the f/4 and f/22 settings.
- Optimized for filming, the lens supports active mode image stabilization and micro-step aperture control for smooth and seamless video capture.
- Two programmable focus hold buttons and a focus mode switch for intuitive focus control.
- Minimum focusing distance of 9.8" with excellent close-up performance at all focal lengths.
Handling and Design
- Hybrid construction uses both metal and plastic components to maximize both durability and a low weight design.
- Fluorine coating on front lens element repels water, dust, fingerprints, and other contaminants while also making it easier to clean the front of the lens.
- Dust and moisture-resistant design includes a rubber ring to seal the lens mount for working in inclement weather conditions.
