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08-31-2019, 06:52 AM   #1
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Join Date: Aug 2019
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K5 front focusing in close distance and back focusing far

Hi all. I have been watching the forum for quite some time. This is my first post though.

A couple of months ago I took my K5 and my pentax da 50mm 1.8 to the authorised

Ricoh repair centre in Athens, Greece. I asked the guy there to check/adjust the af accuracy.
The guy called me on the phone to say the lens was spot on. I told him I had applied an extreme
af correction (something like -18). He said he 'd check again. He called again and said everything was

normal and something along the lines "af adjustment is for very minute problems..."
I paid the fee for checking, as I understand he did nothing to the camera.

At the moment I didn't insist and thought maybe he knows better. My shots continued to be

inconsistent of course.

Recently and after extensive testing I realised that there is significant difference according to focusing distance.

Both my lenses (I also have the tamron 17-50 2.8)display considerable front focusing. The problem is if I correct it using a target
say 1m away, then it back-focuses at something 5m away, and vice versa.

The difference of adjustment needed between 1m and 10m

is about 8 units in the autofocus autoadjustment.

I have used various methods to check and adjust this. I think using the live view and then switching to viewfinder
yields the best results, but I have also used charts, perpendicular and inclined, and tested thoroughly in the field.

To catch some obvious questions: I have always used high contrast targets, with both vertical and horizontal lines.
I only used the centre af point. I am aware of narrow dof at 1.8. I am aware of recomposing errors. I am aware of the

sr messing with focusing. Live view focusing has always been spot on. My results have been consistent nevertheless with the thread title.

Any help would be much appreciated


08-31-2019, 06:40 PM   #2
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Join Date: Mar 2019
Posts: 329
QuoteOriginally posted by nskan Quote
Hi all. Live view focusing has always been spot on. My results have been consistent nevertheless with the thread title.

Any help would be much appreciated

Does the image in live view differs from what you see in the optical viewfinder?
08-31-2019, 07:29 PM   #3
Just1MoreDave's Avatar

Join Date: Feb 2007
Location: Aurora, CO
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Posts: 5,744
The original K-5 had problems focusing in incandescent light. I think this was just in PDAF and not CDAF. Later versions of the firmware made this better but make sure your tests are in similar color temperatures.

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