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09-27-2009, 01:04 AM   #1
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K-7 AF adjustment survey

Hi All,

Just curious what AF adjustment do you perform for your K-7. I have to do the following for my lenses.

FA 50mm f1.4 : AF -10, but still have front focus at f1.4-2.0, otherwise good.
DA 16-45mm f4: AF -6, a little front focus for f4, otherwise good.
DA 55-300mm: AF -5, good.

It seems that I have a front focusing K-7 body since all my lenses needs negative adjustments. What about yours?

Thanks,
Tony

09-27-2009, 02:06 AM   #2
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QuoteOriginally posted by fulcrumx29 Quote
Hi All,

Just curious what AF adjustment do you perform for your K-7. I have to do the following for my lenses.

FA 50mm f1.4 : AF -10, but still have front focus at f1.4-2.0, otherwise good.
DA 16-45mm f4: AF -6, a little front focus for f4, otherwise good.
DA 55-300mm: AF -5, good.

It seems that I have a front focusing K-7 body since all my lenses needs negative adjustments. What about yours?

Thanks,
Tony


I haven't done any tests, but I've been shooting it for nearly 3 months now and haven't been bothered by any of my pics to prompt me to test. Did you buy those lenses specifically for the K-7, or did you use them with your previous body? If you're seeing the FF for the first time, then surely, your K-7 body is at fault.
09-27-2009, 09:44 AM   #3
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When I read about the K20 and it's focus bias feature, I was afraid this sort of thing would be the result.
What's happening (I think, anyway) is that the cameras are being shipped semi-calibrated (physical sensor placement), under the assumption that the user will do the final tweaks.
Good enough until you send out a camera that is so far out of whack that the user has to max out the focus bias and still can't get a good adjustment.
My K20 has this exact problem. Several lenses have to be set to -10, and still aren't quite there, but all my lenses are set to the minus side of things.
My K-7 is better, thankfully.
09-27-2009, 10:00 AM   #4
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Hmmm. I have to say that I initially started messing around with the AF to see how it worked but I shoot only Limited lenses at the moment and have never applied AF adjustment to any of the lenses. They all focus perfectly for me.

That said, I recently purchased a used Sigma 100-300mm f/4 that had significant backfocus issues that is now on its way back to Sigma Repair. It would focus increasingly behind the subject any time it was used with AF. I could MF the lens without issue but the AF... "es ist kaputt".

I'd be interested at the distances that you are having AF issues. My experience has been very good with the K-7 but the 100-300mm got worse the further away I focused.

Here's a related question: What does Pentax charge to have your camera and lenses calibrated together? I mean, let's say 4-5 lenses and a camera body? My experience is with Canon and their professional service contract was set up just for stuff like this...

09-27-2009, 10:14 AM   #5
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QuoteOriginally posted by Rich_A Quote


Here's a related question: What does Pentax charge to have your camera and lenses calibrated together? I mean, let's say 4-5 lenses and a camera body? My experience is with Canon and their professional service contract was set up just for stuff like this...
That will depend a lot on whether it is considered a warranty repair or not. I believe with Pentax Canada one can send in a warranted body and lens for mechanical calibration as a warranty service.
Apparently it isn't all that difficult, the bottom plate comes off the camera and there are three screws that set the placement of the AF sensor to adjust.
I'm guessing that the sensor can be adjusted in all three planes to cure front or back focus and also to move the sensor closer to the viewfinder indicators.
I expect Pentax USA should offer something similar.
I'll be sending my K20 off for calibration very soon while it is still under warranty, and them my K-7 may be going in after that.
09-27-2009, 11:44 AM   #6
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Original Poster
Hi Rich,

Yes, the focusing problem will increase as you shoot distant objects. I consider like this, the relative error is the same, but the actual error depends on relative multiply by distance. Does it make sense?

Tony
09-27-2009, 11:53 AM   #7
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Hi Wheatfield,

I read the famous 3 screws story of ist D, but when I opened my K-7 I did not see any of those screws. :-)

Tony
09-27-2009, 12:07 PM   #8
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QuoteOriginally posted by fulcrumx29 Quote
Hi Wheatfield,

I read the famous 3 screws story of ist D, but when I opened my K-7 I did not see any of those screws. :-)

Tony
Presumption on my part. I just assumed that they wouldn't have changed this.
My bad.

09-27-2009, 03:00 PM   #9
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Withthe K7 I have only tested my da40 and da70 LTDs. Both have ff. DA 40 is at -10 and DA 70 is at -4. I tend to agree with the sensor adjustment theory because they both back focus on the k100d.

IMO, the advent of individual lens adjustment in camera is an admission of the lack of precision in contruciton and lack of quality control.
09-27-2009, 04:42 PM   #10
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Hi Schmik,

Kind of agree with the laziness in construction and QC. My former low end ist DL never has ff issues for another 50 1.4.

It seems we have to send the K-7 with lens in to adjust. I also have a tilted horizon correction but perfect vertical correction.

Thanks,
Tony
09-27-2009, 05:18 PM   #11
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I haven't had significant problems with any of my lenses.though having said that the focus my FA31mm f/1.8 limited has been a bit sketchy at times.
09-28-2009, 02:28 PM   #12
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One of K20D's is at 0 and perfect. (bought the day it came out)
My second K20D is at +8 and perfect. Bought on amazon for $549.00 day special
My dads K20Dis +5 and perfect Bought at B$H for $649.00 recently
MY K-7 is at 0 and perfect...(bought the day it came out)

It is my guess that the very first are quite good until they are mass produced....
09-28-2009, 06:17 PM   #13
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QuoteOriginally posted by jgredline Quote

It is my guess that the very first are quite good until they are mass produced....
I disagree.... i got mine on preorder and it has a very early serial number.

Also, are you suggesting at you use a universal AF adjustment number.... not different numbers for individual lenses?

mike
09-28-2009, 06:20 PM   #14
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QuoteOriginally posted by schmik Quote
I disagree.... i got mine on preorder and it has a very early serial number.

Also, are you suggesting at you use a universal AF adjustment number.... not different numbers for individual lenses?

mike
No problem, I am just glad mine is good.
09-28-2009, 06:25 PM   #15
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Pentax K7 bought ~1 month ago in Australia.

-10 on my Tamron 17-50 f2.8
-4 on my Pentax FA50
-5 on my Sigma 70-200 f2.8

believe it or not this is actually an improvement on my K20D not even the max -10 correction would bring my Sigma 70-200 to normal. The Tamron was only at -7 however on the old body... go figure?
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