Fine focus adjust with DFA 28-105?

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Uloo
Uloo Senior Member • Posts: 2,912
Fine focus adjust with DFA 28-105?

I have a Pentax K-1m2 and the DFA 28-105. I noticed recently that my pictures are looking soft. So I did a test and found out that at different focal length the fine adjust is different.

-at 28mm its +4

_at 50mm its -4

-at 105 mm its -5

Is this pretty normal for this lens or is this just happening over times.

How do you people deal with that?

Thank you for any input.

Ulrich

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ozdean
ozdean Forum Pro • Posts: 26,979
Re: Fine focus adjust with DFA 28-105?
1

I set my zooms to the longest focal length wide open.

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Regards Dean - Capturing Creation
N.B. All my Images are Protected by Copyright

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Rahto Senior Member • Posts: 1,452
Re: Fine focus adjust with DFA 28-105?

My lens calibrating stuff was already setup so I grabbed my K1 and 28-105 and tested it. Mine ended up as a -3 at 28, 50 and 105 on the K1 and required no changes on the K3 III. I think Dean’s suggestion of setting it for the 105 is your best option.

Bob

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Uloo
OP Uloo Senior Member • Posts: 2,912
Re: Fine focus adjust with DFA 28-105?

Thanks Dean I will try that. Another thing I noticed even though the focus calibration is way off. When I set the camera for pixel shift the pictures came out tack sharp... That surprised me.

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5r82 Contributing Member • Posts: 629
Re: Fine focus adjust with DFA 28-105?

I put mine on +7 and it works great. I think it depends on individual sample of the lens as all seem to be different in some ways when it comes to AF micro adjustment.

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PeterPentax
PeterPentax Contributing Member • Posts: 971
Re: Fine focus adjust with DFA 28-105?

Uloo wrote:

I have a Pentax K-1m2 and the DFA 28-105. I noticed recently that my pictures are looking soft. So I did a test and found out that at different focal length the fine adjust is different.

-at 28mm its +4

_at 50mm its -4

-at 105 mm its -5

Is this pretty normal for this lens or is this just happening over times.

How do you people deal with that?

Thank you for any input.

Ulrich

How many times are you testing the lens at each FL to come up with your +4 at 28mm for example ?

Gary Martin
Gary Martin Veteran Member • Posts: 4,916
Re: Fine focus adjust with DFA 28-105?

One calibration value (set at the longest focal length) should be sufficient, so there's something else going on here. Maybe you should revisit your focus adjusting technique, there are lots of YouTube videos which are helpful.

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