The Sony 50mm Macro 2.8 is a very lightweight, compact lens :) I use it on my A77. The glass harmonizes very well with my A77. The handling is great and the AF is very, very accurate and very fast even for a Marco :) The tube runs max. 48mm from but falling through the lightweight construction of the lens garnicht more on ...!
I find the Sony 50mm 2.8 better than the 60mm Macro of Tamron. That I could call my own some time ago. I sold it again because it could not fully convince me.