[tduell]

My DFA 150-450 auto focus is a bit off, and my latest tests indicate it is still not quite right at -10.
I'm pondering on taking the lens to the distributor to see if they can correct it.
Does anyone know if that can be done without them having to alter the AF system settings on camera?
Most of my other lenses don't require any AF fine adjust on my K-3 Mark III, and I'd not like to be without the camera for the time it takes to do the adjustments.

Cheers,
Terry

[Joetitch]

IIRC from other posts, the lense itself can be sent in for recallibration. It may be a case of mechanical failure. These have been known to separate in the middle as well. Not a common problem but it has happened. Hope it all turns out well.

[clackers]

My DFA 150-450 auto focus is a bit off, and my latest tests indicate it is still not quite right at -10.
I'm pondering on taking the lens to the distributor to see if they can correct it.
Does anyone know if that can be done without them having to alter the AF system settings on camera?
Most of my other lenses don't require any AF fine adjust on my K-3 Mark III, and I'd not like to be without the camera for the time it takes to do the adjustments.

Cheers,
Terry

That lens is out of spec by the sound of it, since your other lenses are not like it, so you just need them to bring it back within tolerances and when it comes back you recalibrate it with all your bodies, no need to affect other lenses and their settings.

[Oldbayrunner]

I have never had a lens that I've noticed needing fine tuning... With that said I wonder about just how accurate fine tuning a full frame lens actually is with an Apsc sensor due to the overshoot of the image on that sensor. It would seem it would be more accurately calibrated if the lens image being fine tuned was being projected the same as the sensor size.

[clackers]

I have never had a lens that I've noticed needing fine tuning... With that said I wonder about just how accurate fine tuning a full frame lens actually is with an Apsc sensor due to the overshoot of the image on that sensor. It would seem it would be more accurately calibrated if the lens image being fine tuned was being projected the same as the sensor size.

Well, the sensor size doesn't matter, Oldbayrunner because what's used is the separate autofocus sensor in the base of the camera, and its pixels.

[Oldbayrunner]

Well, the sensor size doesn't matter, Oldbayrunner because what's used is the separate autofocus sensor in the base of the camera, and its pixels.

Ok, since Af fine focus adjust works primarily for a single focal length just how does one accurately fine tune a zoom lens with it's varied focal lengths and aperture range changes? I don't believe there is a Pentax camera body as yet that can AF save tuning adjustments for every focal length within a zoom lens' range. It would seem as though one could only AF fine tune to their most frequently used focal length and aperture range selection for that lens then with saving it any other focal length wouldn't necessarily be fine-tuned. One could/can adjust certain Sigma for Pentax zoom lens using their dock for each focal length and aperture then save for that but that is within the lens firmware not within the camera body also it shouldn't be used with any camera body Af adjustment..
Since the OP is talking about a super zoom lens then to me the adjustments they are making may be for naught. Seems to me a better option is to use to use Quick Shift focus for nailing focus since it can minutely adjust for a given focus point either front or back at the focal length being used within that zoom lens.

[zapp]

Pentax service can re-zero camera & lens. The idea is to minimize fine adjustment. Typically they ask you to send in the camera along with the lens, but single lens should also be possible.

---------- Post added 06-06-23 at 01:11 PM ----------

Ok, since Af fine focus adjust works primarily for a single focal length just how does one accurately fine tune a zoom lens with it's varied focal lengths and aperture range changes? I don't believe there is a Pentax camera body as yet that can AF save tuning adjustments for every focal length within a zoom lens' range. It would seem as though one could only AF fine tune to their most frequently used focal length and aperture range selection for that lens then with saving it any other focal length wouldn't necessarily be fine-tuned. One could/can adjust certain Sigma for Pentax zoom lens using their dock for each focal length and aperture then save for that but that is within the lens firmware not within the camera body also it shouldn't be used with any camera body Af adjustment..
Since the OP is talking about a super zoom lens then to me the adjustments they are making may be for naught. Seems to me a better option is to use to use Quick Shift focus for nailing focus since it can minutely adjust for a given focus point either front or back at the focal length being used within that zoom lens.

You only get one correction value that applies globally. I don´t really think Pentax is providing an internal LUT for different focal length and apertures.
If you correct for one setting, other focal length will not be off by factor 10, so it is still worthwhile and you can fine tune your favorite setting.

[Lowell Goudge]

My DFA 150-450 auto focus is a bit off, and my latest tests indicate it is still not quite right at -10.
I'm pondering on taking the lens to the distributor to see if they can correct it.
Does anyone know if that can be done without them having to alter the AF system settings on camera?
Most of my other lenses don't require any AF fine adjust on my K-3 Mark III, and I'd not like to be without the camera for the time it takes to do the adjustments.

Cheers,
Terry

What focus settings are up you using and is focus done with AF-S or AF-C. I find that some of the focus options on the K3-3 can yield different / poor results. I struggled early on with the 150-450 (plus 1.4x TC) on my K3, until I forced the camera to AF-C and centre spot focusing, now it happily sits at +3 on AF fine adjust, although the same combo on my K1-2 needed no adjustment.

I have set mine for the 450 mm (maximum) focal length because for birding most of my shots are at that focal length.

[Oldbayrunner]

Pentax service can re-zero camera & lens. The idea is to minimize fine adjustment. Typically they ask you to send in the camera along with the lens, but single lens should also be possible.

---------- Post added 06-06-23 at 01:11 PM ----------



You only get one correction value that applies globally. I don´t really think Pentax is providing an internal LUT for different focal length and apertures.
If you correct for one setting, other focal length will not be off by factor 10, so it is still worthwhile and you can fine tune your favorite setting.

Again it still may not be necessarily accurate for another focal length, that is my point... And I did state you could fine tune to your favorite focal length.. I think I'll leave my perfectly fine Dfa 150-450mm alone and use its focus shift to fine tune my shots instead of monkeying with it.... LOL

[clackers]

Ok, since Af fine focus adjust works primarily for a single focal length just how does one accurately fine tune a zoom lens with it's varied focal lengths and aperture range changes?

But that's a different matter, you were making a claim about sensor size.

To calibrate a 70-300 f4-5.6 lens with its range of lengths and apertures is the same problem on APS-C as FF.

[Oldbayrunner]

But that's a different matter, you were making a claim about sensor size.

I beg to differ with you I made no such claim, had you have read my post correctly "With that said I wonder about " is usually in the English language meant as a thought process inquiry for which you answered to my satisfaction. My second post was indeed an entirely different matter.

To calibrate a 70-300 f4-5.6 lens with its range of lengths and apertures is the same problem on APS-C as FF.

Correct, though I don't believe my 2nd post made a mention of this being a difference in any one format but was worded as a whole for both formats and all zoom lens.

[tduell]

What focus settings are up you using and is focus done with AF-S or AF-C.

For my testing, I'm using spot focus, AF-S, tripod mount, 2 sec timer and cable release.
After discussions with the distributor, it is now looking like the K-3 Mark III body may be part of the problem.
Testing the lens with my K-3 II and K-1, suggests that both these bodies require an AF Fine adjustment in the range -2 to -3...so essentially the same.
So looking like both K-3 Mark III and lens off to the doctor.

Cheers,
Terry

[Lowell Goudge]

For my testing, I'm using spot focus, AF-S, tripod mount, 2 sec timer and cable release.
After discussions with the distributor, it is now looking like the K-3 Mark III body may be part of the problem.
Testing the lens with my K-3 II and K-1, suggests that both these bodies require an AF Fine adjustment in the range -2 to -3...so essentially the same.
So looking like both K-3 Mark III and lens off to the doctor.

Cheers,
Terry

Try AF-C I think you will find that it works better
It did for me

[tduell]

Try AF-C I think you will find that it works better
It did for me

I don't think AF-S is an issue here, I'm getting consistent results with each of the cameras.

Cheers,
Terry