I happen to have two sigma mid-rang zooms for Minolta Maxxum and Sony Alpha. They have equal similarity and difference.
- Plastic lens mount and barrels
- Front elements do not turn with focusing.
- The rear elements move with zooming.
- 55mm filter size
- Macro switches at longest focus length (80 vs. 90mm)
- Fully extended at 80/90mm and shortest focus length
- The largest macro rates are 1:2 on 28-80mm and 1:2.3 on 28-90
- With 8 contact pads, the 28-90mm lens equivalent to Minolta D and Sony Alpha lens.