Back focus problem or not?

Hi everyone, I recently bought Alpha 580, my first DSLR, I am used to shoot with Dynax 7 and X-500/700.
The first thing I noticed is that I tend to have many more unsharp/out-of-focus shot with the 580 and I have the impression that it tends to focus behind the target while in the OVF I see the target as sharp.
I have never noticed so many misses while shooting with the Dynax 7, so I wonder if my A580 has a back focusing issue.
Here are some examples/test-shots that suggest that the AF misses the target mainly when I shoot handheld, so it is maybe the SteadyShot of the A580 that mismatches my handshaking.

#1 AF-A, SteadyShot ON, lens Minolta 100-200 F4,5; it was handheld so it may also be my handshake/subject moving: the target was the boy but the hair of the girl behind and to the right are sharper.
#1

#2 AF-S, SteadyShot ON, lens Minolta 100-200 F4,5; it was handheld: the target was the green leaf at the foot of the pole but the tiles behind it are sharper
#2

#3 AF-S, lens Minolta 35-105 f3,5-4,5; camera on tripod with 2sec self-timer: the target was the Smurf I do not see back focusing
#3

#4 AF-S, lens Minolta 35-105 f3,5-4,5; camera on tripod with 2sec self-timer: the target was the bear, I do not see back focusing
#4

#5 AF-S, lens Sony SAM 15-50 f3,5-5,6; camera on tripod with 2sec self-timer: the target was the bear, I do not see back focusing
#5

#6 AF-S, lens Sony SAM 15-50 f3,5-5,6; camera on tripod with 2sec self-timer: the target was the Smurf, it may be back focusing or it may be the AF that chose the pig i.p.o. the Smurf.
#6

#7 AF-S, lens Sony SAM 15-50 f3,5-5,6; camera on tripod with 2sec self-timer: the target was the green "tree" behind the orange "monkey", I do not see back focusing
#7

Edited by compragio - 31 December 2011 at 00:21

Check out mhoner's page you'll find a decent explanation of front/back focus on This page.

To be certain about this issue, you need a controlled setup.   You can quickly build a rig similar to a LensAlign out of a cereal box and a ruler.   You may find consistent back or front focus or you may find different ff or bf for different zooms at different focal lengths or even focus distances. Make sure you check using ranges relevant to your shooting.

If you discover varying problems, you just have to live with that as the 580 doesn't have user accessible micro focus adjust. If you have a consistent bf, you may just be able to cure it by adjusting the famous 3 screws but you may prefer to have Sony do this under warranty.

Good luck! The murky world of focus adjustment can lead to much frustration!

Edited by mikey2000 - 01 January 2012 at 08:13

except that hohner's explanation is not entirely accurate, at least where he states that focusing problems are never lens-related but it's always the camera to blame.

I have had lenses calibrated that did not af correctly while other lenses did, and had the problem with that particular lens rectified - camera untouched, continuing to work with other lenses as before.

You probably already have found multiple discussions on this topic, and might have come across links to lens service manuals describing lens af adjustment procedures which most likely would not exist if af accuracy was entirely camera dependant.