Sigma's versatile APS-C standard zoom for Sony A — the 17-70mm f/2.8-4 Contemporary.
The Sigma 17-70mm f/2.8-4 DC Macro OS HSM Contemporary for Sony A mount is the same versatile APS-C zoom described in Pentax K under ID 3830. It covers 25-105mm equivalent with a fast f/2.8 starting aperture, macro capability, OS stabilisation, and HSM quiet AF. The Contemporary designation indicates compact design with quality optics.
Optical performance is good. Centre sharpness is very good at wider focal lengths. The fast f/2.8 start provides brighter viewfinder and more DOF control than kit zooms. OS stabilisation supplements Sony's body SR. HSM motor is quieter than body screw-drive. The macro mode enables close-up work. The 25-105mm equivalent range is versatile for everyday use.
Sony A mount, APS-C. Filter thread is 72mm. Weight is approximately 470 grams. Build quality is good Contemporary tier. The dual stabilisation (OS + Sony body SR) provides excellent handheld performance. HSM motor operates independently of the body motor. The A-mount system is discontinued but the lens adapts to E-mount via LA-EA adapters.
Available at reasonable prices. Check OS, AF, and smooth zoom. A very capable everyday zoom for Sony A-mount shooters. The dual stabilisation is a significant advantage. The declining A-mount demand keeps prices attractive. Adapts well to E-mount with maintained AF functionality.