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04-20-2010, 07:43 PM   #1
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K20D - all sorted out (AF)

When I purchased my K20D, all my lenses back focused and was happy that I could correct them with the Custom Functions. However, my MF lenses, using the focus indication, still back focused and my newly acquired (2 samples) 15mm Limited's back focus was beyond the custom function's ability.

The problem was solved, for me, when I learned of this site:

Andy McMullan Blog Archive Debug mode on the Pentax K20D DSLR

I set a nominal back focus adjustment determined from my lenses. I then went about retesting my lenses and setting the new adjustments - including the 15mm. All was great until I checked the focus indication for my MF lenses. They still back focused but now, only a tiny amount.

I finally corrected the problem by using the debug mode to set the focus indication for the MF lenses and then corrected all my MF lenses through the custom menu.

I am extremely pleased with the results.

As simple as the solution was, I suggest that Pentax, through the AF custom menu, apply the "All" to all the lenses (correct the focus indication) and then be able to modify that correction for individual lenses.

04-21-2010, 08:53 AM   #2
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I am going to have to reserve a weekend to check out that site, set up a test suite, and check out my lenses. I have tried the built-in AF adjustment but have never felt that I had everything correct. Maybe this is one reason I prefer to manually focus.

Thanks for the info!
04-21-2010, 09:40 AM   #3
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Nice find; I've often wondered if there was a global control to change the baseline from which the AF adjustment was basing its adjustments on.

All but one of my lenses are either dead on or need only an adjustment of up to 3 points to feel really good; that single lens doesn't seem to want to behave even with a max of 10 points dialed in.

Can't remember from the K10D debug process, but -0x0 um means more backfocus, right (versus +0x0 um]?
04-21-2010, 09:44 AM   #4
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QuoteOriginally posted by bobrapp Quote
When I purchased my K20D, all my lenses back focused and was happy that I could correct them with the Custom Functions. However, my MF lenses, using the focus indication, still back focused and my newly acquired (2 samples) 15mm Limited's back focus was beyond the custom function's ability.

The problem was solved, for me, when I learned of this site:

Andy McMullan Blog Archive Debug mode on the Pentax K20D DSLR

I set a nominal back focus adjustment determined from my lenses. I then went about retesting my lenses and setting the new adjustments - including the 15mm. All was great until I checked the focus indication for my MF lenses. They still back focused but now, only a tiny amount.

I finally corrected the problem by using the debug mode to set the focus indication for the MF lenses and then corrected all my MF lenses through the custom menu.

I am extremely pleased with the results.

As simple as the solution was, I suggest that Pentax, through the AF custom menu, apply the "All" to all the lenses (correct the focus indication) and then be able to modify that correction for individual lenses.





Your proposed solution is a very sensible one. In fact, why in the heck haven't they done that???

04-21-2010, 12:10 PM   #5
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Thanks for the info on this, on my K20D my 16-45mm was back-focusing ever so slightly and the in camera adjustments made quick work of it. On top of that you will notice that I have a vast amount of manual focus lenses as well and all of these seem to focus perfectly. However, I am really glad that you showed me this as this could help me in the future.
04-21-2010, 07:24 PM   #6
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QuoteOriginally posted by rparmar Quote
I am going to have to reserve a weekend to check out that site, set up a test suite, and check out my lenses. I have tried the built-in AF adjustment but have never felt that I had everything correct. Maybe this is one reason I prefer to manually focus.

Thanks for the info!
I hope it works as well for you as it did for me.
04-21-2010, 07:29 PM   #7
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QuoteOriginally posted by legacyb4 Quote
Nice find; I've often wondered if there was a global control to change the baseline from which the AF adjustment was basing its adjustments on.

All but one of my lenses are either dead on or need only an adjustment of up to 3 points to feel really good; that single lens doesn't seem to want to behave even with a max of 10 points dialed in.

Can't remember from the K10D debug process, but -0x0 um means more backfocus, right (versus +0x0 um]?
Yes, you are right if the lens front focuses, you would dial in a negative number.
The procedure will work for the K10 - you have to change a few things. See:

Debug mode

I have not tested it on my K10D and may give it a try this weekend.
04-21-2010, 08:15 PM   #8
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QuoteOriginally posted by bobrapp Quote
When I purchased my K20D, all my lenses back focused and was happy that I could correct them with the Custom Functions. However, my MF lenses, using the focus indication, still back focused and my newly acquired (2 samples) 15mm Limited's back focus was beyond the custom function's ability.

The problem was solved, for me, when I learned of this site:

Andy McMullan Blog Archive Debug mode on the Pentax K20D DSLR

I set a nominal back focus adjustment determined from my lenses. I then went about retesting my lenses and setting the new adjustments - including the 15mm. All was great until I checked the focus indication for my MF lenses. They still back focused but now, only a tiny amount.

I finally corrected the problem by using the debug mode to set the focus indication for the MF lenses and then corrected all my MF lenses through the custom menu.

I am extremely pleased with the results.

As simple as the solution was, I suggest that Pentax, through the AF custom menu, apply the "All" to all the lenses (correct the focus indication) and then be able to modify that correction for individual lenses.
I am happy to read this post as an owner of a K20D, and a K7.
That will be a great way to adjust any lens, right? Does it work for any lens, even the non-Pentax types?
Also, following your link from your post, I see that whomever wrote the code guides us to another link to adjust AF for the K7 ... however, once there, it clearly shows that this is for the Kx, and not the K7.
Is there such a hack code for the K7 as well?
Cheers.

JP

04-21-2010, 10:24 PM   #9
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QuoteOriginally posted by jpzk Quote
I am happy to read this post as an owner of a K20D, and a K7.
That will be a great way to adjust any lens, right? Does it work for any lens, even the non-Pentax types?
Also, following your link from your post, I see that whomever wrote the code guides us to another link to adjust AF for the K7 ... however, once there, it clearly shows that this is for the Kx, and not the K7.
Is there such a hack code for the K7 as well?
Cheers.

JP
I am not an owner of the K7. See the previous post for the K7D key.
04-21-2010, 11:28 PM   #10
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So I just checked the settings on all my lenses; they range from zero correction on some, maybe +2 or +4 points dialed in on others, and +10 on one particular lens (the one I'm still not satisfied with). My K20D is currently set to +/- 0 in the debug settings.

If I understand the logic correctly, I should then dial in a positive um number (what is the um equivalent to +/1 on the regular AF correction scale?) to positively offset the global default setting (effectively bringing forward focusing every lens). This would then mean all lenses in their current settings would have to be adjusted for minus steps except for the lens with +10 already dialed in (in effect it has been bumped to more than +10).

Guess I'll have to do some testing!


QuoteOriginally posted by bobrapp Quote
Yes, you are right if the lens front focuses, you would dial in a negative number.
The procedure will work for the K10 - you have to change a few things. See:

Debug mode

I have not tested it on my K10D and may give it a try this weekend.
04-22-2010, 12:23 AM   #11
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QuoteOriginally posted by legacyb4 Quote
So I just checked the settings on all my lenses; they range from zero correction on some, maybe +2 or +4 points dialed in on others, and +10 on one particular lens (the one I'm still not satisfied with). My K20D is currently set to +/- 0 in the debug settings.

If I understand the logic correctly, I should then dial in a positive um number (what is the um equivalent to +/1 on the regular AF correction scale?) to positively offset the global default setting (effectively bringing forward focusing every lens). This would then mean all lenses in their current settings would have to be adjusted for minus steps except for the lens with +10 already dialed in (in effect it has been bumped to more than +10).

Guess I'll have to do some testing!
Actually, as I read it and from some quick fiddling, when you set the "DEBUG" adjustment + it will set the camera to compensate for any inbody BF issues (adjustments in the positive direction bring the in-focus area closer to you is a way to look at it...negative adjustments are for FF issues and move the in-focus area away from you). So, the amount you need to adjust your +10 lense, for example, will decrease depending on the total amount of debug adjustments you make. If you use that lense to set the camera as the reference lense, then that lense should not need any custom AF adjustment, or at worst much less Custom AF Adjustment. Of course this should change the adjustments for your other lenses as you have set a new point of reference for the body. Say a lens that was previously a +4 might now be a -6 or so...it seems to be a tap dance on first glance but surely will allow the saving of many trips for calibration.

My question is what are the "Test Area" settings? Is "Test Area 0" the center AF area then the other areas are different quadrants of the frame? If that is correct any sensor alignment issues, which might actually appear as de-centering on a given lense or all of them, might be user address fixable given enough patience. Or do I have this sort of confused?
04-22-2010, 06:56 AM   #12
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Thanks for posting your experience. It is good to keep it in mind.



QuoteOriginally posted by bobrapp Quote
When I purchased my K20D, all my lenses back focused and was happy that I could correct them with the Custom Functions. However, my MF lenses, using the focus indication, still back focused and my newly acquired (2 samples) 15mm Limited's back focus was beyond the custom function's ability.

The problem was solved, for me, when I learned of this site:

Andy McMullan Blog Archive Debug mode on the Pentax K20D DSLR

I set a nominal back focus adjustment determined from my lenses. I then went about retesting my lenses and setting the new adjustments - including the 15mm. All was great until I checked the focus indication for my MF lenses. They still back focused but now, only a tiny amount.

I finally corrected the problem by using the debug mode to set the focus indication for the MF lenses and then corrected all my MF lenses through the custom menu.

I am extremely pleased with the results.

As simple as the solution was, I suggest that Pentax, through the AF custom menu, apply the "All" to all the lenses (correct the focus indication) and then be able to modify that correction for individual lenses.
04-22-2010, 07:22 AM   #13
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Thanks. While I wouldn't necessarily use the +10 lens to set the new zero AF adjustment point, I'll try to find the happy average between all my gear so that none of the lenses have any extreme adjustments dialed in.

Still wonder what +/- 1 conversion factor is for actual um settings?

Cheers.

QuoteOriginally posted by brecklundin Quote
If you use that lense to set the camera as the reference lense, then that lense should not need any custom AF adjustment, or at worst much less Custom AF Adjustment. Of course this should change the adjustments for your other lenses as you have set a new point of reference for the body. Say a lens that was previously a +4 might now be a -6 or so...it seems to be a tap dance on first glance but surely will allow the saving of many trips for calibration.
04-22-2010, 07:39 AM   #14
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QuoteOriginally posted by bobrapp Quote
I am not an owner of the K7. See the previous post for the K7D key.
OK I'll do that when I find that last post you mention.
Thanks.
JP
04-22-2010, 12:15 PM   #15
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I'm the author of the blog post with the K20D instructions - glad to see it's been useful to someone.

One thing to watch out for is the light you do your adjustments in. I originally did my adjustments in tungsten light, and then found they were wrong for daylight.

In the end I reset the debug mode AF to its default, and now when I use my FA 50mm F1.4 I set the standard AF adjustment to either -10 (for tungsten light) or 0 (for daylight). Quite tedious really - I hope they sorted this out on the K7.
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