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05-21-2015, 04:05 PM   #1
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K3 - does AF Fine Adjustment impact focus confirmation for MF mode / lenses?

Hi folks - quick question... If I use one of my fully manual lenses on the K3 and focus through the viewfinder, will the AF Fine Adjustment setting alter where the focus confirmation triggers?

I've noticed with a few of my manual primes that the point of best focus is not necessarily where the camera thinks it is It's not really a problem, as with manual lenses I tend to ignore that and rely on visual focusing of the image - but it would be nice to know if I can adjust the focus confirmation to be accurate. I'm guessing it *should* work, as it's using the same phase detection functionality as regular AF, no?

Thanks in advance...

05-21-2015, 04:16 PM   #2
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I think there's enough tolerance to the point where the fine adjustments are insignificant. But yes, I do believe they would still be in effect.

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05-21-2015, 04:26 PM   #3
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QuoteOriginally posted by Adam Quote
I think there's enough tolerance to the point where the fine adjustments are insignificant. But yes, I do believe they would still be in effect.
Thanks, Adam. In fact, my Helios 44m 2/58 when paired with my old K5 is right on the edge of the focus confirmation range, so I may play with the AF Fine Adjustment and see if I can centre the focus point within the confirmation range.

Any ideas as to why the tolerances on the confirmation range are so wide?
05-21-2015, 04:29 PM   #4
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QuoteOriginally posted by BigMackCam Quote
Any ideas as to why the tolerances on the confirmation range are so wide?
I think it's mainly because the AF system is designed to make micro adjustments and obtain feedback from the lens.


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05-21-2015, 04:48 PM   #5
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QuoteOriginally posted by BigMackCam Quote
If I use one of my fully manual lenses on the K3 and focus through the viewfinder, will the AF Fine Adjustment setting alter where the focus confirmation triggers?
I believe the AF fine focus can move the point of focus confirmation. But as Adam pointed out there is so much 'slop' in the AF confirmation that it is not reliable at any aperture under maybe f/5.6. Far better to use the focusing screen.

Also, note that there is only one 'general' setting for all lenses, so adjusting for your Helios will also adjust for all other manual lenses. Only lenses with ID chips can use the AF fine tuning on a lens by lens basis.

Also, AFAIK, with manual lenses the AF confirm is only using the center AF point so if you are trying to get something even just slightly off center in focus the AF confirm light is not your friend.
05-22-2015, 01:16 AM   #6
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I realized this behavior with my K Lenses. When I try to use the Catch-in-Focus, the focus confirmation does not fit. Pentax Germany told me that there is no ID Chip on the one side and on the other side the catch-in-focus only works exakt from f5.6 up.
The problem does not exist with Lenses with A contacts.
05-22-2015, 01:31 AM   #7
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My own experience with manual focus lenses (with or without A setting) is that the AF fine adjustment does affect the accuracy of the PDAF system with the "apply all" setting. I can often nail shots even with wide-open aperture say f1.4. On my k-3, I have front focus issue so I need -10 or -9 whereas on my k-5IIs, I will need -6 to align it correct. As others have suggested, as long as it is within the tolerance of the PDAF system in the camera, it will have some effect. Unfortunately, if it falls outside of the -10 to +10 range, you are out of luck, which usually means that it needs to be calibrated by Pentax technician.
05-22-2015, 07:00 AM   #8
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QuoteOriginally posted by jatrax Quote
Only lenses with ID chips can use the AF fine tuning on a lens by lens basis.
Can anyone confirm whether F lenses "qualify" (i.e., do F lenses have ID chips)? Or, are FA lenses the oldest lenses that can have their AF fine tuning done individually? Thanks.

05-22-2015, 08:17 AM - 1 Like   #9
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QuoteOriginally posted by fwcetus Quote
Can anyone confirm whether F lenses "qualify" (i.e., do F lenses have ID chips)?
Yes they do. I think any lens that has an ID code that can be distinguished qualifies.
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