[hnikesch]

I also tried the DOT with my KP but will stick with images in both VL and OVF seems more precise to me

DA 55-300 PLM -/+0
DA 18-135 -/+ 0
DA 50mm f1.8 -/+0
DA 35 mm f2.4 +3

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Last edited by hnikesch; 11-22-2019 at 12:53 PM.

[rogerstg]

I did try the DOT method, but I seemed to get focus confirmation on almost anything (+4 to -10).

That's how it should work, by giving you a range. In your case, I'd use -3 or -4, depending on the strength of the -10 confirmation, since +/-10 are the limits of the adjustment range.

The dot tune method accepts the reality that there is an adjustment range at which a camera will interpret something as "in focus" and sets the fine tune adjustment to the center of that range. The more common method (fastidious test setup, test shots, interpretation of each shot, guessed adjustment; repeat test shots, interpretation of each shot, guessed adjustment; repeat . . .) seems to rely on tireless testing with the hope of stumbling on a representative sample of the camera's AF tolerances to find the acceptable range of adjustment.

[mikesbike]

Just curious if other KP owners have the same experience with this.

I haven't had to adjust for any of my lenses. I've used the DA*50-135, HD DA 55-300, DA 50/1.8, DA 18-55, Sigma 17-70 and Tamron 75-300. All have been spot on without any adjustments.

With the K10D and K-7 every lens required adjustment.

Did I hit the AF lottery or is this the norm for a KP?

Same with me, and I have numerous lenses that I've used with it.

[Vmax911]

That's how it should work, by giving you a range. In your case, I'd use -3 or -4, depending on the strength of the -10 confirmation, since +/-10 are the limits of the adjustment range.

The dot tune method accepts the reality that there is an adjustment range at which a camera will interpret something as "in focus" and sets the fine tune adjustment to the center of that range. The more common method (fastidious test setup, test shots, interpretation of each shot, guessed adjustment; repeat test shots, interpretation of each shot, guessed adjustment; repeat . . .) seems to rely on tireless testing with the hope of stumbling on a representative sample of the camera's AF tolerances to find the acceptable range of adjustment.

Thanks for the clarification. I expected the range to be smaller. The fact that the limit of the camera's adjustment parameters was still within the acceptable range took away some confidence in the measurement. But the more info the better I guess.

[rogerstg]

Thanks for the clarification. I expected the range to be smaller. The fact that the limit of the camera's adjustment parameters was still within the acceptable range took away some confidence in the measurement. But the more info the better I guess.

Yes, it makes sense that the slower or wider a lens, the greater the depth of field and greater the range that the camera will find focus acceptable. Though butting against one of the camera's adjustment limits forces a guess or interpretation of where the actual limit might be. Regardless, using your case as an example, -3 or -4 is a logically better setting than zero.

Had you noticed a problem or were you being proactive?

[Vmax911]

Yes, it makes sense that the slower or wider a lens, the greater the depth of field and greater the range that the camera will find focus acceptable. Though butting against one of the camera's adjustment limits forces a guess or interpretation of where the actual limit might be. Regardless, using your case as an example, -3 or -4 is a logically better setting than zero.

Had you noticed a problem or were you being proactive?

No issues, just wanted to try the technique out. Lens is currently set at zero and will stay there until I get more time on it.

[hnikesch]

I tried the DOT method but got different range on second try same object on several lenses?? so sticking with images

[simple1]

Recently added the DFA 150-450. Haven't done a lot of shooting with it yet but, so far, AF seems dead on.

IMO it's really nice not having to got through the adjustments, regardless of procedure.

Of course now, if I ever get a new body, my expectations may be too high

[wstruth]

Recently added the DFA 150-450. Haven't done a lot of shooting with it yet but, so far, AF seems dead on.

IMO it's really nice not having to got through the adjustments, regardless of procedure.

Of course now, if I ever get a new body, my expectations may be too high

Ditto for me as well. All my lenses have worked well without focus adjustments.

[Ronald Oakes]

I only have 3 modern AF Pentax lenses , but the DA 35 Limited macro is the only one that needed anything. I think is was a +2 IIRC.

[ZombieArmy]

All my lenses have needed some adjustment unfortunately with the KP (usually -1 to -4). However it's dead on now. Maybe I'm just more of a peeper though.

[gatorguy]

I think I already know my answer but thought I'd run it by some of the more experienced guys...

I rented an HD DA50 over the holidays and used it extensively. Probably 500 shots or more. Wonderful lens, crisp images and great color rendering if maybe almost surgical. Liked it so much I ordered my own from B&H. Rec'd it Friday and used over the weekend. Way too many soft images compared to the rental. Checked focus this morning, did several fine adjustments and determined the lens was pretty far of, requiring a -7 to the severe (IMO) front focusing.(yes used a lens-align tool and confirming with followup photos outdoors of a bookpage at 25' and concrete block wall detail after correction)

TBH this is only the second lens of mine that required any adjustment at all, the other being my DA*300 which needed a +1 (or maybe 2 not sure, and not easy to do). Barely off anyway.

This HD DA50 can off course be corrected in body but it would make my Katz Eye focus screen pretty useless for manual focusing with it. A premium lens like this one should need minimal or no adjustment I would think. Should it go back to B&H for another copy of it and are they good about making an exchange for this kind of issue?

I love the lens in general but don't really want to real with the auto-focus issue.

[fsge]

I think I already know my answer but thought I'd run it by some of the more experienced guys...

I rented an HD DA50 over the holidays and used it extensively. Probably 500 shots or more. Wonderful lens, crisp images and great color rendering if maybe almost surgical. Liked it so much I ordered my own from B&H. Rec'd it Friday and used over the weekend. Way too many soft images compared to the rental. Checked focus this morning, did several fine adjustments and determined the lens was pretty far of, requiring a -7 to the severe (IMO) front focusing.(yes used a lens-align tool and confirming with followup photos outdoors of a bookpage at 25' and concrete block wall detail after correction)

TBH this is only the second lens of mine that required any adjustment at all, the other being my DA*300 which needed a +1 (or maybe 2 not sure, and not easy to do). Barely off anyway.

This HD DA50 can off course be corrected in body but it would make my Katz Eye focus screen pretty useless for manual focusing with it. A premium lens like this one should need minimal or no adjustment I would think. Should it go back to B&H for another copy of it and are they good about making an exchange for this kind of issue?

I love the lens in general but don't really want to real with the auto-focus issue.

Why not swapping it for another copy? B&H should understand if this one is a dog.
I experienced the same with a sigma 85 f1.4 copy I bought from a well known French retailer some years ago. I sent them some pics and negative comments and they accepted to exchange it. I received a very good copy instead and had no regret about my complaining

[gatorguy]

Why not swapping it for another copy? B&H should understand if this one is a dog.
I experienced the same with a sigma 85 f1.4 copy I bought from a well known French retailer some years ago. I sent them some pics and negative comments and they accepted to exchange it. I received a very good copy instead and had no regret about my complaining

@Fsge, that's probably what I'm going to do, just wanted to find out if anyone else has had a similar issue and whether B&H was easy to work with to exchange.

[rogerstg]

This HD DA50 can off course be corrected in body but it would make my Katz Eye focus screen pretty useless for manual focusing with it.

I don't understand this conclusion. Why wouldn't it work with the other focusing screen?
BTW, lots of precision equipment needs calibration to work best. If the lens works within the calibration range, it works as designed and should not be considered a "dog."