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11-19-2017, 11:43 AM   #1
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Don't forget to adjust AF calibration for your lenses when using the DA 1.4x tc

I was calibrating my lenses this weekend, and noticed that when I attached the pentax da 1.4x Tc to my lenses, all the saved AF micro adjustments would be reset to "0" . I don't know if this is something that's been covered before in the forum, but thought to give you guys a heads up on the issue.

DA* 300 + 1.4x Tc (left "0" adjustment, right "+1" adjustment)

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11-19-2017, 01:07 PM   #2
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The main issue, at least with the copy of DA300 I used, was AF consistency. With regards to AF consistency , the DFA150-450 compared to DA300 is like day and night, that makes fine AF adjustment much more effective.
11-19-2017, 02:17 PM - 1 Like   #3
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QuoteOriginally posted by Stavri Quote
I was calibrating my lenses this weekend, and noticed that when I attached the pentax da 1.4x Tc to my lenses, all the saved AF micro adjustments would be reset to "0"
It would be odd to me at least if that were not the case. Any lens + TC is a whole new optic as far as the camera is concerned.

The difference between your two photos looks a lot for a +1 adjustment and is more likely to be a sample variation. When you calibrate a lens/camera combo you need to do around 10 tests at each setting and go on a majority vote. i have yet to calibrate any Pentax lens that will give 10/10 exactly identical results. Camera AF is just not that accurate.

Last edited by pschlute; 11-19-2017 at 02:37 PM.
11-19-2017, 02:56 PM   #4
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Thanks for reminder - I have not used TC extensively so far, but of course it should be calibrated.

11-19-2017, 03:29 PM   #5
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QuoteOriginally posted by pschlute Quote
It would be odd to me at least if that were not the case. Any lens + TC is a whole new optic as far as the camera is concerned.

The difference between your two photos looks a lot for a +1 adjustment and is more likely to be a sample variation. When you calibrate a lens/camera combo you need to do around 10 tests at each setting and go on a majority vote. i have yet to calibrate any Pentax lens that will give 10/10 exactly identical results. Camera AF is just not that accurate.
That is a good point, one shot cannot accurately convey the offset. I took over 275 calibration shots this past Saturday for 8 lenses. I keep all info of my lenses in an excel database, (serial number, calibration adjustments before and after firmware updates), +1 was the calibration info on file of the DA* 300, coupled with 1.4x tc it required the same amount of adjustment.

On a side note, the camera body will keep a record of the lens + tc af adjustment when specified by the user, otherwise the combo will "0"

Last edited by Stavri; 11-19-2017 at 03:44 PM.
11-19-2017, 03:33 PM   #6
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QuoteOriginally posted by Stavri Quote
On a side note, the camera body will keep a record of the lens + tc af adjustment when specified by the user, otherwise the combo will "0"
That is very useful to know, thanks.
11-19-2017, 06:09 PM   #7
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That could be why I have been having "problems" with this specific TC attached to my DA*300/4 ...
Thanks for the hint.
Something to try and see if it will solve the said-problem.

---------- Post added 11-19-17 at 08:15 PM ----------

QuoteOriginally posted by Stavri Quote
I was calibrating my lenses this weekend, and noticed that when I attached the pentax da 1.4x Tc to my lenses, all the saved AF micro adjustments would be reset to "0" . I don't know if this is something that's been covered before in the forum, but thought to give you guys a heads up on the issue.

DA* 300 + 1.4x Tc (left "0" adjustment, right "+1" adjustment)
So, let's say (presumption only) I had the DA*300/4 on its own and needed a +1 fine adjustment ... and I saved that "correction".
Then, I attach the HD 1.4X TC to that same lens ... so according to your findings, the required AF adjustment (if any) would be reset to zero, right?
Once I calibrate this combo and save it, would the camera save it as a lens on its own (i.e.: the lens plus TC = "a lens" ) ?
11-19-2017, 07:37 PM   #8
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QuoteOriginally posted by jpzk Quote
That could be why I have been having "problems" with this specific TC attached to my DA*300/4 ...
Thanks for the hint.
Something to try and see if it will solve the said-problem.

---------- Post added 11-19-17 at 08:15 PM ----------



So, let's say (presumption only) I had the DA*300/4 on its own and needed a +1 fine adjustment ... and I saved that "correction".
Then, I attach the HD 1.4X TC to that same lens ... so according to your findings, the required AF adjustment (if any) would be reset to zero, right?
Once I calibrate this combo and save it, would the camera save it as a lens on its own (i.e.: the lens plus TC = "a lens" ) ?
Correct, your previous AF calibration of +1 on the DA* 300, would be "erased" from the camera's memory once the TC is attached, you have to manually input such adjustment with the lens + tc attached once more. Once done, the camera will remember the Lens + TC combo setting. In my testing the K1 consideres the lens + tc as a new lens, creating an unique profile for each lens + tc combination. One could theoretical have a +1 adjustment on the DA* 300, and then an -4 adjustment on the lens + TC combo, the camera will revert to +1 for the DA* 300 when the TC is removed, and apply -4 automatically once the TC is attached. I would recommend to perform a whole new set of calibrations optics, when attaching the TC to an already micro-adjusted telephoto lens.


Last edited by Stavri; 11-19-2017 at 07:44 PM.
11-19-2017, 09:04 PM   #9
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QuoteOriginally posted by Stavri Quote
Correct, your previous AF calibration of +1 on the DA* 300, would be "erased" from the camera's memory once the TC is attached, you have to manually input such adjustment with the lens + tc attached once more. Once done, the camera will remember the Lens + TC combo setting. In my testing the K1 consideres the lens + tc as a new lens, creating an unique profile for each lens + tc combination. One could theoretical have a +1 adjustment on the DA* 300, and then an -4 adjustment on the lens + TC combo, the camera will revert to +1 for the DA* 300 when the TC is removed, and apply -4 automatically once the TC is attached. I would recommend to perform a whole new set of calibrations optics, when attaching the TC to an already micro-adjusted telephoto lens.
Thanks Stavri.
Seems confusing but I will give it a go and see what happens.
I'll have to find a proper set up and "target" for this.
11-19-2017, 11:17 PM   #10
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QuoteOriginally posted by jpzk Quote
Seems confusing but I will give it a go and see what happens.
Hi Jacques, whatever AF lens ( or TC and lens combinations ) corrections are " saved," they will be remembered and applied when that combination is mounted to the camera. My 100mm macro WR needed an AF correction of +9 when mounted by itself, but a +4 correction when used with the TC. The EXIF data also relays the correct focal length when used with Pentax AF lenses too. The 100mm by itself registers as 100mm, but 140mm when used with the TC.
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