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FA* 300mm f4.5 jittery focus problem?

Started Sep 30, 2013 | Questions thread
Walt_A Senior Member • Posts: 2,136
Re: FA* 300mm f4.5 jittery focus problem?

I've got the FA*300 4.5 and the K-30 and I don't recognise these symptoms excepts as follows:

I find photographing birds in trees/grass or butterflies/insects in grass for example the af it not very positive and will flit between subject and background/foreground. This is in centre af and AF-C handheld, so I now switch to AF-S and and it locks onto the subject more often than not.

This is exactly what happens with my Tamron 70-300 LD Di and K-30.

My FA*300 was used extensively with my GX10 and K100D before this without those symptoms in those situations. I noticed it on the K-30 almost straight away as wildlife is what I shoot most. I figured it's just the price I have to pay for faster AF-C on pentax....

Other issues with AF-C and the FA* have cropped up when using auto and 5 point selection when it looses a subject (such as birds in flight) and is completely out of focus, it just sits there continually focusing back/forward's in a very short range, so jittery would probably describe that (again this happens with the tamron as well, and again this never happens on the GX10 or K100D). In single point AF-C this never happens. So it doesn't sound like the problems you describe, does it?

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