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04-26-2011, 03:26 AM   #1
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K20D back focus issues

Just been playing with my K20D and a few lenses and discovered that I needed to adjust the AF by between +5 and +10 with most lenses. In some cases even a little more adjustment would have been required to really correct the BF problems. So, 2 questions:

1. Given that I did not have make adjustments for all my lenses (my Sigma 70-200/2.8 was spot on), is BF a camera issue or a lens issue?

2. Is it usual to have to make the sorts of large adjustments that I did?

Cheers,
Qiki

04-26-2011, 08:16 AM   #2
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1. BF is generally a lens issue. Lens are calibrated in factory but it's impossible to calibrate every lens for every type of camera and some fine adjusting may need to be done.

2. Yes
04-26-2011, 06:24 PM   #3
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QuoteOriginally posted by Pauld Quote
1. BF is generally a lens issue. Lens are calibrated in factory but it's impossible to calibrate every lens for every type of camera and some fine adjusting may need to be done.

2. Yes
Thanks for the reply. Since my original post I printed out a focus test chart and went back and made my AF adjustments again. However I found that I needed far less adjustment when testing with the chart (requiring focus from close range) than I needed when doing my original tests (focussing on objects 2-3m away). So, now I'm confused. Do I make the AF adjustments based on the A4 sized test chart, or on 'real' objects a little further away??

Qiki
04-27-2011, 10:05 AM   #4
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I adjusted my lens to the focal length that normally shoot with that lens. Worked out good for me.I used Lightroom to help determine most used focal range for each lens.
Mike

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