Sigma has announced the 28-70mm F2.8 DG DN. This new lens now joins the 14-24mm f/2.8 DG HSM, 24-70mm F2.8 DG DN, 24-105mm f/4 DG OS HSM, and 12-24mm f/4 DG HSM in the full-frame Art series zooms.
This lens is available in either L-Mount or Sony E-mount.
Smaller & Lighter
Sigma 28-70mm F2.8 DG DN 
Sigma 24-70mm f/2.8 DG DN
The 28-70mm F2.8 DG DN is based on Sigma’s existing 24-70mm F2.8 DG DN lens, however, by making the widest focal length 28mm instead of 24mm, Sigma has been able to make this lens significantly smaller and lighter. According to Sigma, this is the smallest and lightest lens in its class.
To keep the weight down the lens features a simpler dust- and splash-proof structure and smaller switches. Sigma is also using just one lightweight focusing element, which keeps the AF unit small.
Now, the lens isn’t made out of metal, instead, it uses a type of polycarbonate called TSC (Thermally Stable Composite), which has a comparable level of thermal shrinkage to aluminum. This helps reduce differences between the thermal shrinkage of the metal and non-metal parts, ensuring stable levels of performance even in an environment with extreme temperature changes. The use of polycarbonates in the construction of zoom and focus rings can make their operation feel less premium, however, Sigma claims that the operation of the lens is still smooth and consistent.
All of this results in a lens that weighs just 470g (1.03 lb). As a comparison, the 24-70mm F2.8 DG DN weighs 1020g (2.24 lb)
As another comparison, the Canon RF 28-70mm f/2L USM Lens weighs 1430g (3.15 lb). Yes, it is a lot faster at F2, but that’s more than 3x heavier than the Sigma 28-70mm F2.8 DG DN.
Optical Design
The optical design of the 28-70mm F2.8 DG DN | Contemporary features 16 elements in 12 groups, with three aspherical, two FLD, and two SLD elements. The lens also has 9 aperture blades.
Despite using fewer elements in total than the 24-70mm F2.8 DG DN | Art, Sigma claims that the design results in a thorough correction of axial chromatic aberration and sagittal coma aberration, which cannot be corrected in-camera, allowing users to create images that are uniformly sharp from the center to the edges of the frame.
Along with its anti-ghosting design, the use of Super Multi-Layer Coating and Nano Porous Coating is claimed to control flare for high-contrast results in backlit conditions. It also features a water and oil repellant coating on the front side of the lens.
Just like the 24-70mm F2.8, this lens also extends when you are zooming.
Key Specifications
- Lens construction: 16 elements in12 groups, with 2 FLD elements, 2 SLD elements and 3 aspherical elements
- Internal focusing
- Compatible with high-speed autofocus
- Stepping motor
- Compatible with lens-based optical correction
- Function available on supported cameras only. Available corrections may vary depending on the camera model.
- Nano Porous Coating
- Super Multi-Layer Coating
- Water and oil repellent coating (front element)
- Focus Mode Switch
- Support DMF, AF+MF
- Petal-type lens hood
- Simple dust- and splash-proof design
- Compatible with SIGMA USB DOCK UD-11 (sold separately / for L-Mount only)
- Designed to minimize flare and ghosting
- Every single lens undergoes SIGMA’s proprietary MTF measuring system “A1”
- 9-blade rounded diaphragm
- High-precision, durable brass bayonet mount
- ‘Made in Japan’ craftsmanship
Price & availability
The 28-70mm F2.8 DG DN will retail for $899 USD and it should be available from March 12, 2021.
28-70mm focal length lenses are not overly common. Sony has its own FE 28-70mm f/3.5-5.6 OSS Lens but that features a variable aperture and is more of an affordable kit style lens than anything else.
