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10-31-2009, 12:37 PM   #1
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AF point off center??

HI Folks -

Has anyone ever seen an AF point move significantly off-center? I recently reinstalled my kit lens after using a bunch of older manual lenses and it appears to have moved significantly - and it sometimes changes position when I remove and reinstall the lens. I'm thinking that this is a lens issue because it's dead-center on my older lenses but I don't know for sure. About 2 weeks ago I installed a katzeye focusing screen and all seemed fine and still looks OK in that department.

Any ideas?

Thanks!

Chris

10-31-2009, 01:24 PM   #2
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The AF sensor of my old Ds shifted upward by 30-50% against the focus screen centre bracket, my K-m downward by the same amount. The spot meters (the whole meter sensors actually) were calibrated based on the AF sensors too from what I can tell. You may reinstall and shift the focus screen a little trying to reduce the error, but probably never perfect. I myself have repositioned the meter sensors to match the focus screen so that the spot meter would be accurate and predictable, but there is nothing you (or the technican) can do with the AF sensor imho because the way Pentax DSLRs were designed do not invite such high precision.
10-31-2009, 01:54 PM   #3
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How do you move the focusing screen just by dismounting manual lenses and remounting the kit lens?
10-31-2009, 02:17 PM   #4
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QuoteOriginally posted by Judd Quote
Has anyone ever seen an AF point move significantly off-center? I recently reinstalled my kit lens after using a bunch of older manual lenses and it appears to have moved significantly
How do you know it has moved? Do you mean the little red light that shows up in the viewfinder to tell you sort of more less approximately where the AF point is, or do you mean you tested to find the actual location? And are you sure you were using the center point.

10-31-2009, 04:12 PM   #5
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I should have spoken more precisely - the AF indicator LED has moved and it also appears that the focus point has moved with it...BUT this only occurs with the kit lens and it's moved around significantly. (First it was about 30% upper right, then about 60% dead right, then about 30-40% lower right - all today).

With a manual lens it's centered. If I leave the autofocus on with a manual lens, the camera will actually beep and flash the LED when the center of the image comes into focus as I'm turning the focus ring, so I figure that the camera itself if probably OK but I'm not sure.
10-31-2009, 05:38 PM   #6
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Nevermind...I was seeing the LED for the auto-exposure move around. I reset a few things and all seems normal. Oops!

Hey, I usually shoot manually on old lenses!
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