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02-15-2011, 06:29 AM   #1
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Focus correction for DA* 16-50

Hi all,

I've got a DA* 16-50 which need +10 correction to be reasonable sharp, is there some way to get more correction ?
Or is there a screw or something on the lens mount to give it more back/front focus for the lens itself or something ?

Well the question is simple, is het possible to get more correction than the maximum 10 points I get on my K20D body.

My (Samsung) DA 10-17 focuses tack sharp without ANY focus correction on the same body so I dont expect it is related to the body.

Regards,
Priyantha

02-15-2011, 06:50 AM   #2
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I don't know the answer. I too have been disappointed with the IQ and sharpness of my DA*16-50mm. It seems no amount of +/- correction with my K7 can deliver the same sharpness I get from my DA*50-135mm lens.

Last week I shipped the 16-50 off to PentaxRepairs in Tennesse to let Eric look it over. Hopefully, he will find a way to tweak it into shape, and bring it up to the standards we expect from DA* lenses.

Edit[4/3/2011]:
Eric tested my 16-50 and reported it was 'dead on', perfect. So I looked into other 'operator error' causes and I found ...

I discovered what I beleive to be the main source of my blury 16-50 problem, and it watches me shave every morning in the mirror. Short version: Turn SR off when mounting lens on tri-pod for AF fine tuning. Thank you "Magic Lantern Guide" for pointing out my folly! After receiving & reading through most of the MLG this weekend, I re-ran the DA*16-50mm AF calibration test [SR off!] and it was 'dead-on', +/-0 adjustment needed. It is a testament to the lens design that I did get some decent shots out of it, even though it was grossly mis-calibrated by it's 'clueless' owner at -6.

Last edited by Moe49; 04-13-2011 at 09:22 AM.
02-15-2011, 07:37 AM   #3
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You can use the Debug Mode to change the "baseline" offset of the camera AF.

Informations on how to enter Debug Mode here: Debug mode
02-15-2011, 07:46 AM   #4
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I had the same problem and send in the lens and the body at the Pentax service center, it came back corrected in the lens and not in the body.
This was free as the lens and the body were still under warranty.
But after about a year, I had to correct additionally for +2 in the body. I think that any correction isn't permanent and thus I check regularly the corrections of all my lenses what sometimes results in a new correction for some lenses.


Last edited by philippe; 02-15-2011 at 08:12 AM.
02-15-2011, 07:53 AM   #5
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QuoteOriginally posted by RBellavance Quote
You can use the Debug Mode to change the "baseline" offset of the camera AF.

Informations on how to enter Debug Mode here: Debug mode
Not listed on that link but the file name for the K-x is: MODSET.492
and you have to power up while holding the Av +/- button.

Recent fine tuning made a night and day difference on my K-x / Sigma 18-50 f2.8 combo.
04-13-2011, 10:07 AM   #6
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Are you leaving the Shake Reduction [SR] on while performing the AF adjustment?
I recently found out that is a NO-NO.

Edit to my earilier post above[2/15/2011]:
Eric tested my 16-50 and reported it was 'dead on', perfect. So I looked into other 'operator error' causes and I found ...

I discovered what I believe to be the main source of my blury 16-50 problem, and it watches me shave every morning in the mirror. Short version: Turn SR off when mounting lens on tri-pod for AF fine tuning. Thank you "Magic Lantern Guide" for pointing out my folly! After receiving & reading through most of the MLG this weekend, I re-ran the DA*16-50mm AF calibration test [SR off!] and it was 'dead-on', +/-0 adjustment needed. It is a testament to the lens design that I did get some decent shots out of it, even though it was grossly mis-calibrated by it's 'clueless' owner at -6.
04-13-2011, 05:14 PM   #7
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QuoteOriginally posted by Moe49 Quote
the same sharpness I get from my DA*50-135mm lens.
You are on the same wild goose chase here that I was, three years ago. I then believed that all * lenses were created equal, and that my DA* 16-50 should be the equal of my F* 300/4.5. It's not going to happen, the 50-135 is in a completely different class of its own, and any comparisons should be deemed unfair. To be fair, it should be remembered thats if far more difficult to design and build an ultrawide zoom, than a mid tele zoom.
04-13-2011, 05:38 PM   #8
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I tried 2 copies of 16-50 and neither were good, autofocus was way out and the IQ wasn't that great. My 50-135 though has stunning IQ. I'm not rushing to try a 3rd copy of the 16-50 put it that way.

04-13-2011, 08:59 PM   #9
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I have every reason to be happy with my third copy of the DA* 16-50. You gave up too soon, perhaps.
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