DA21 - age-old focusing question

timo · 12-14-2012, 06:50 PM

HI all

I got the DA21 soon after it was released. Always had focusing issues, but worked around it mostly by manual focusing (and it didn't seem as bad on the K10D, for some reason). Now that I have the K-5 with the ability to fine-adjust the AF, I have been able to test more precisely what the problem is. If you adjust the focus for wide apertures (up to f4, say) it front-focuses massively at f8. Conversely, get it right for landscapes etc., then it back focuses wide open. I know this is an old problem, widely reported a few years back, and was probably corrected during production of the lens.

My question is, did anyone send their lens back to be re-callibrated, or reprogrammed, or whatever the term is, did it work, and did it cost a lot of money? Obviously mine is many years out of warranty. If it's just a matter of an electronic tweak, it would be worth doing. If they actually have to open it up and change something, then it'll sit in Japan for weeks and the bill will be enormous.

Any experience of this? Is it worth sending it in?

Thanks.

Tim

Adam · 12-14-2012, 07:10 PM

Originally posted by timo

HI all

I got the DA21 soon after it was released. Always had focusing issues, but worked around it mostly by manual focusing (and it didn't seem as bad on the K10D, for some reason). Now that I have the K-5 with the ability to fine-adjust the AF, I have been able to test more precisely what the problem is. If you adjust the focus for wide apertures (up to f4, say) it front-focuses massively at f8. Conversely, get it right for landscapes etc., then it back focuses wide open. I know this is an old problem, widely reported a few years back, and was probably corrected during production of the lens.

My question is, did anyone send their lens back to be re-callibrated, or reprogrammed, or whatever the term is, did it work, and did it cost a lot of money? Obviously mine is many years out of warranty. If it's just a matter of an electronic tweak, it would be worth doing. If they actually have to open it up and change something, then it'll sit in Japan for weeks and the bill will be enormous.

Any experience of this? Is it worth sending it in?

Thanks.

Tim

Because of the 21mm's uge DOF, I wouldn't expect FF or BF to not have much of an adverse effect on landscape photos. What you're describing sounds like a defect in the lens itself, and will probably cost you just as much to repair as it would to buy a new lens.

timo · 12-14-2012, 07:23 PM

Originally posted by Adam

Because of the 21mm's uge DOF, I wouldn't expect FF or BF to not have much of an adverse effect on landscape photos. What you're describing sounds like a defect in the lens itself, and will probably cost you just as much to repair as it would to buy a new lens.

Adam, it is definitely a focusing issue. If you manually focus for landscapes (i.e. to the extreme end of the focusing travel), it is perfectly sharp. But if you adjust AF for a wide aperture, for a long-distance shot the AF will position it just short of the beginning of the infinity mark. It doesn't sound much, but with this lens the focusing travel is so small that it makes all the difference, even at f/8. I understand what you're saying about DOF, which is why in practice manual focusing for general shots is perfectly viable.

12-14-2012, 06:50 PM	#1
timo Veteran Member Join Date: Nov 2006 Location: former Arsenal football stadium Photos: Gallery Posts: 431	DA21 - age-old focusing question HI all I got the DA21 soon after it was released. Always had focusing issues, but worked around it mostly by manual focusing (and it didn't seem as bad on the K10D, for some reason). Now that I have the K-5 with the ability to fine-adjust the AF, I have been able to test more precisely what the problem is. If you adjust the focus for wide apertures (up to f4, say) it front-focuses massively at f8. Conversely, get it right for landscapes etc., then it back focuses wide open. I know this is an old problem, widely reported a few years back, and was probably corrected during production of the lens. My question is, did anyone send their lens back to be re-callibrated, or reprogrammed, or whatever the term is, did it work, and did it cost a lot of money? Obviously mine is many years out of warranty. If it's just a matter of an electronic tweak, it would be worth doing. If they actually have to open it up and change something, then it'll sit in Japan for weeks and the bill will be enormous. Any experience of this? Is it worth sending it in? Thanks. Tim

12-14-2012, 07:10 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Originally posted by timo HI all I got the DA21 soon after it was released. Always had focusing issues, but worked around it mostly by manual focusing (and it didn't seem as bad on the K10D, for some reason). Now that I have the K-5 with the ability to fine-adjust the AF, I have been able to test more precisely what the problem is. If you adjust the focus for wide apertures (up to f4, say) it front-focuses massively at f8. Conversely, get it right for landscapes etc., then it back focuses wide open. I know this is an old problem, widely reported a few years back, and was probably corrected during production of the lens. My question is, did anyone send their lens back to be re-callibrated, or reprogrammed, or whatever the term is, did it work, and did it cost a lot of money? Obviously mine is many years out of warranty. If it's just a matter of an electronic tweak, it would be worth doing. If they actually have to open it up and change something, then it'll sit in Japan for weeks and the bill will be enormous. Any experience of this? Is it worth sending it in? Thanks. Tim Because of the 21mm's uge DOF, I wouldn't expect FF or BF to not have much of an adverse effect on landscape photos. What you're describing sounds like a defect in the lens itself, and will probably cost you just as much to repair as it would to buy a new lens. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

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12-14-2012, 07:23 PM	#3
timo Veteran Member Join Date: Nov 2006 Location: former Arsenal football stadium Photos: Gallery Posts: 431 Original Poster	Originally posted by Adam Because of the 21mm's uge DOF, I wouldn't expect FF or BF to not have much of an adverse effect on landscape photos. What you're describing sounds like a defect in the lens itself, and will probably cost you just as much to repair as it would to buy a new lens. Adam, it is definitely a focusing issue. If you manually focus for landscapes (i.e. to the extreme end of the focusing travel), it is perfectly sharp. But if you adjust AF for a wide aperture, for a long-distance shot the AF will position it just short of the beginning of the infinity mark. It doesn't sound much, but with this lens the focusing travel is so small that it makes all the difference, even at f/8. I understand what you're saying about DOF, which is why in practice manual focusing for general shots is perfectly viable.