[Maksat Tutan]

Hello Pentaxians,

I have upgraded to the k5 recently and bought Sigma 18-250 superzoom.
I don't have many af lens to check its AF. But the Sigma 18-250 was focusing on back. it was noticeable and anyone can tell there is a problem on focusing when seeing LCD display.

Then I used my manual lens to catch focus with assist of k5's focus confirmation.
k5 indicates a focus light when focus point on back.
When using live view to use contrast detection AF, result was far better.
Object distance on lens when focused using contrast detection was nearer than the indicated distance when using using AF sensor.

So I guessed that there were problems on body.
Then used AF fine adjustment in body function, tried to make two distances indicated on lens nearer, and set +10 on all lenses.
Result was becoming nicer, I mean focus point was coming towards to actual point from back. But it was not enough.

Then used the PK_Tether, latest version to make the k5 in debug mode and set micro adjustment to +100um.
It means +10 point on inbody fineadjustment becomes 0 after the +100um setting.

Now AF focuses better with settings of +4 (in AF fine adjustment) plus +100um (set in debug mode). It equals +14 on AF fine adjustment settings.

But focus calibration on superzoom lens is difficult, couldn't set sweet number on AF fine adjustment settings to let the lens produce sharpest on wide variety of focal length.

But with +14, my gears make almost sharpest results with widest open and it delivers sharpest results when stopped down to f8.0.

I am so happy with the result.

[johnyates]

I am so happy with the result.

"Tuning" your camera for accurate focus can certainly be a PITA, but it's well worth the effort.