Sony's A-mount constant f/2.8 standard zoom — the 28-75mm SAM for full-frame A-mount bodies.
The Sony 28-75mm f/2.8 SAM is a constant-aperture standard zoom for Sony A mount, offering the professional f/2.8 specification with SAM lens-based autofocus. Based on the same optical formula as the Tamron 28-75mm f/2.8 (Tamron manufactured lenses for Sony's A-mount system), it provides the essential standard zoom coverage for A-mount full-frame shooters.
Optical performance is good — the same well-regarded optics as the Tamron A09. Centre sharpness is excellent from f/2.8. The constant f/2.8 provides consistent exposure and DOF. Bokeh is smooth. The SAM motor provides lens-based AF, freeing the body motor for other functions. Benefits from Sony's SteadyShot INSIDE body stabilisation.
Sony A mount, full-frame. Filter thread is 67mm. Weight is approximately 565 grams — moderate for a constant f/2.8 zoom. Build quality is decent. No in-lens stabilisation — uses Sony body SR. The SAM motor is quieter than body screw-drive AF. Compatible with all Sony A-mount bodies and adaptable to E-mount via LA-EA adapters.
Available at very low used prices — declining A-mount demand. Check AF accuracy and smooth zoom. A solid constant f/2.8 standard zoom at an attractive price. The A-mount decline makes this a bargain for the specification. Adapts to E-mount with maintained AF via LA-EA5.