Camera Labs

I am currently the owner of a Canon 450d but with a baby coming along in 4 weeks I want to upgrade to a camera that also has high quality video - so I'm opting for the brand new Sony A57.

Currently with the Canon I have a great all round 17-85 lense. Understanding that I need a lense that will allow the Sony A57 to use auto focus in video mode, and that I want to get great shots of my new baby but also be able to handle anything that comes my way, what's the best equivalent Sony lense or lenses?

Thanks in advance!

I really liked the Zeiss 16-80 while I had that on Sony, but it is screw driven AF so I don't know if it'll be too noisy for video. Since then they have also bought out a 16-50mm f2.8 SSM which might help there, if you don't mind the shorter zoom. Both are however in a higher class than the 17-85. How's the budget?

If you need to look cheaper, I think that swings towards Sigma lenses. In a quick look, some possible options are:
17-70mm f/2.8-4 DC OS Macro HSM
18-50mm f/2.8-4.5 DC OS HSM
18-125mm f/3.5-5.6 DC OS HSM

Roughly speaking HSM = USM = SSM, so all should have nice and quiet AF. I don't know what their optical performance is like though. Some (older) Sigma lenses may have trouble with the Sony SLT bodies so that might be something check if you go that route.

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Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.