Minolta AF 20mm 2.8: only AF on center?

[isaac_leung]

<p>I got a Minolta AF 20mm F2.8 just the other day, and decided to test it out on a shoot that morning. I fitted it on the A350, and away I went.<br>

However, I noticed I could only ever properly autofocus using the 5 central AF points on the A350. Attempts to use the four periphery AF points led to out of focus shots.<br>

Additionally, autofocus was very noisy. While not expecting SSM-type noise levels, I have had experience with the Maxxum 50mm 1.7 and 2.8 macro lenses before, and AF with those was never this noisy. Of particular concern were the loud knocking sounds issuing from the 20mm from time to time, as if the AF motor had reached the extreme ends of the focusing ring of the lens, but was trying to go beyond.<br>

Not being able to autofocus on periphery AF points is not such a big problem, especially as I can use the central points then just recompose. However, it is an annoyance which I'd rather do without. <br>

Has anyone else had experience using the Minolta AF 20mm 2.8 on a non-A900 DSLR? Is my copy faulty, or is it just one of those quirks when trying to combine older technology with newer technology?</p>

[wayne_naughton]

<p>You're gonna have a high percentage of out of focus shots and lots of hunting if you use af with a 20mm lens. It's better to focus manually. If it's an older model lens it'll grind and clunk away merrily. Just to be sure you can clean the contacts with a dab of alcohol. Otherwisw sounds reasonably normal to me.</p>