I use the Sony 28-75mm 2.8 on my Alpha 550 and have thus made about 1,500 trips and am fully at peace. I had tried looking for an "Always top" and had in the meantime several models (Zeiss 16-80mm, 18-50mm 2.8-4.5 Sigma HSM, Sony 18-70mm) long. At first I thought the lack of wide angle is a problem. As I looked at my pictures the last 2 years and I noticed that there is hardly wide-angle images were there. Then my other idea was it should also be suitable for full-frame: Yes, you never know whether you but switching to full-frame. The price should be lower than 700 EUR. Since the Sony 28-75mm 2.8 and the corresponding Tamron only stayed over. The crucial point was then for me, the SAM Drive.
Highlights:
++ The maximum aperture of 2.8 ++ The SAM drive, very fast and accurate autofocus, very quiet ++ The weight is super light for a 2.8 lens ++ It is not too big of an APS-C camera (the 2,8er Sigma or Zeiss are compared real Brummer) ++ The slide lock prevents the inadvertent deployment during transport (which was the Zeiss 16-80mm very disturbing)
Even the info:
The lens is inner focusing The tube moves about 3.5cm when zooming out