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12-20-2013, 12:10 PM   #1
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K-3 focus consistency

Hi,
Recently, after shooting my wife students' recital I noticed that some shots with similar parameters are sharper than others. I thought that it's OK due to a lot of variables. But it got me interested.
Today I decided to check it out.
The setup: K-3, sturdy tripod, MLU, remote. Lenses: DA40, DA70 and DA50-135. Lighting: CFL bulbs/flash. Distance to target about 2 m
The result: it seems that with shorter FL (40 and 50 mm) some shots are sharper than the others; with longer FL (70 and 135mm) focus is consistent. When I used flash focus is consistent with all FL.
Also, I switch to focusing with AF button and focus was consistent for all FL with and without flash.
Anybody wants to take a shot at why it happens?
Thank you very much,

P.S. Sorry, forgot to mention - f/w is 1.01

12-20-2013, 12:41 PM   #2
Ole
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Have you by chance disabled focusing with half press of the shutter button?

When activating focusing with the shutter button, do you allow time for the camera to focus properly before pressing the shutter all the way?

Have you checked that focus mode is set to focus priority (rather than release priority) in the custom functions menu?

None of your tests were live view, right?
12-20-2013, 01:31 PM   #3
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QuoteOriginally posted by Ole Quote
Have you by chance disabled focusing with half press of the shutter button? No

When activating focusing with the shutter button, do you allow time for the camera to focus properly before pressing the shutter all the way? I had visual and audio of focus confirmation

Have you checked that focus mode is set to focus priority (rather than release priority) in the custom functions menu? I have Focus priority

None of your tests were live view, right? No live view

Ole,
Please see my answers in red
Thanks,
12-20-2013, 02:50 PM   #4
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Phase-detection isn't perfect and even the expensive Canikons shows some inconsistensy.

12-20-2013, 03:09 PM   #5
Ole
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What's strange is that accurate focus as per the OP is consistently obtained with the AF button for all lenses, but not for two of the lenses when focusing with the shutter button. I'm at a loss here.
12-20-2013, 10:40 PM   #6
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A shot in the dark, here - check that SR is disabled when on the tripod. Second, check the focus points setting. It may be that the wider lenses are focusing on an object that is not in the focus field on the longer lenses. A bit of pixel peeking could find out where they focused, and then you might be able to work out why it happened.
12-21-2013, 11:00 AM   #7
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QuoteOriginally posted by Canada_Rockies Quote
A shot in the dark, here - check that SR is disabled when on the tripod.
OP mentioned MLU so this probably isn't it.

I'm puzzled why AF-ON works but shutter press focus is fuzzy as well...weird...
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