Sigma's earlier 24-70mm f/2.8 for Nikon — the EX DG version before the Art line redesign.
The Sigma 24-70mm f/2.8 EX DG HSM is Sigma's pre-Art-line constant aperture standard zoom for full-frame DSLRs. Competing against the Nikon 24-70mm f/2.8G and Tamron 24-70mm f/2.8 VC, it offered the constant f/2.8 specification at a competitive price. The EX designation indicates Sigma's professional tier from this era.
Optical performance is good but trails the later Sigma 24-70mm f/2.8 Art and the Tamron G2 version. Centre sharpness is very good from f/2.8. Corners are the weakest point, improving significantly by f/4. HSM motor provides fast, quiet autofocus. No image stabilisation — a limitation addressed by the Tamron VC alternative.
Nikon F mount. Filter thread is 82mm — large. Weight is approximately 790 grams. Build quality is solid with the EX professional designation. DG coatings reduce sensor reflections. No weather sealing. The Macro designation indicates closer-than-usual minimum focusing distance. The Sigma 24-70mm f/2.8 Art is the dramatically improved successor.
Available on the used market at very attractive prices — the Art version has driven down demand. Check AF accuracy and smooth zoom operation. Best suited to photographers who want a constant f/2.8 standard zoom at the lowest possible price. The Sigma Art and Tamron G2 are significantly better if budget allows.