Sony's budget A-mount wide prime - the Minolta AF 28mm f/2.8 design carried over, 5 elements, 185g.
The Sony 28mm f/2.8 is an autofocus wide-angle prime for the Sony A bayonet, introduced in 2006 alongside the first Alpha bodies. It is the Minolta AF 28mm f/2.8 carried over unchanged when Sony acquired Konica Minolta's camera division, so the optical design dates from the mid-1980s. It was one of the cheapest primes Sony listed for the A-mount and has since been discontinued.
A 28mm f/2.8 lens of five elements in five groups with a seven-blade aperture stopping down to f/22. Minimum focus is 300mm for a maximum magnification of 0.13x, the filter thread is 49mm, and the lens weighs 185g with a barrel that extends from 44mm to 54mm as it focuses. It covers the full 35mm frame, giving a 42mm equivalent angle of view on an APS-C Alpha body.
On a full-frame body this is a moderate wide-angle suited to landscape, street and interiors; on APS-C it becomes a compact standard lens, which is how most of them were used given that the A-mount range was dominated by APS-C bodies. The simple five-element formula is sharp in the centre from f/4 and benefits from stopping down to f/8 at the edges. Its light weight and short barrel make it an easy lens to keep fitted.
Used copies are common and inexpensive on the A-mount market, where demand has thinned since Sony moved to E-mount. Check the focus screw drive turns smoothly and that the front element is free of the light haze that affects some 1980s-era Minolta glass, since the optics are of that generation. The aperture is electronically controlled, so also confirm the rear contacts are clean. It adapts to E-mount bodies with an LA-EA adapter, though autofocus performance varies by adapter generation.