K10D AF adjustment

Started Feb 12, 2007 | Discussions
mskad Veteran Member • Posts: 3,329
K10D AF adjustment

Shin's post ( http://forums.dpreview.com/forums/read.asp?forum=1036&message=22013971 ) about how to access the service menu and calibrate the K10D AF is the best thing since sliced bread!

I evidently tried to calibrate all my lenses and although I didn't think I had an AF issue, I found a spectacular improvement after adjusting my FA 50mm f/1.4 and my DA 21mm f/3.2.

I also noticed that the adjustment values are quite different if it's under daylight or tungsten conditions.

For the curious, here are "my" adjustment values (daylight/tungsten):

DA 21mm f/3.2 (+40/-20)
FA 31mm f/1.8 (0/-80)
DA 40mm f/2.8 (0/-80)
FA 50mm f/1.4 (-60/-120)
FA 77mm f/1.8 (0/-80)

As you can see, the FA31, DA40 and FA77 are consistent, the DA21 back focuses and the FA50 front focuses.

I also noticed that the K10D AF system is extremely reliable and accurate, once calibrated.

Bottom line: this K10D is getting better and better

Thank you M.S. Shin!

PS: If only Pentax was willing to make this feature easier to use through a firmware update, this could become THE killer feature (Ideally and after calibration, the camera would automatically adjust the offset based on a predefined value for each lens).

K10D (AF adjusted -80) with FA31mm @ f/2.8 - tungsten - ISO 640

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LuzArt Veteran Member • Posts: 6,643
Re: K10D AF adjustment

So this adjustment is lens-specific? As in, the camera remembers the adjustment you make for each lens?

That is quite logical i suppose, given that the lens' data is available to the body.

In terms of functionality, it's truly amazing. Is this possibly with other DSLR's? I imagine it could/would be.

Ben
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hamidlmt Senior Member • Posts: 2,269
Re: K10D AF adjustment

So, do you need to do an adjustment with every lens change?

OP mskad Veteran Member • Posts: 3,329
Re: K10D AF adjustment

LuzArt wrote:

So this adjustment is lens-specific? As in, the camera remembers
the adjustment you make for each lens?

I wish! But unfortunately, it's not the case. Sorry for the confusion. I just said that I hope that Pentax would turn this leaked "secret" into a killer feature and would update the K10D firmware to make access to this adjustement easier.

That is quite logical i suppose, given that the lens' data is
available to the body.

I should be technically doable.

In terms of functionality, it's truly amazing. Is this possibly
with other DSLR's? I imagine it could/would be.

Most likely when the camera is tethered to a computer running the service software, but I never heard of adjusting AF via the menu.

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OP mskad Veteran Member • Posts: 3,329
Re: K10D AF adjustment

Yes. But it only takes about 3 to 5 seconds.

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Lance B Forum Pro • Posts: 32,665
Re: K10D AF adjustment

When you did your focus test, did you use AWB or Tungsten WB? I am theorising that maybe there is a link between the AF and the WB, seeing as the AWB will NOT go down to Tungsten colour temperature of 2,500(?).
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janneman02 Forum Pro • Posts: 15,733
Re: K10D AF adjustment

mskad wrote:

Yes. But it only takes about 3 to 5 seconds.

But you have to remember each value for each specific lens

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Lance B Forum Pro • Posts: 32,665
Re: K10D AF adjustment

janneman02 wrote:

mskad wrote:

Yes. But it only takes about 3 to 5 seconds.

But you have to remember each value for each specific lens

Keep a list in the camera bag and refer to it when you do the adjustment.

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janneman02 Forum Pro • Posts: 15,733
Re: K10D AF adjustment

Lance B wrote:

janneman02 wrote:

mskad wrote:

Yes. But it only takes about 3 to 5 seconds.

But you have to remember each value for each specific lens

Keep a list in the camera bag and refer to it when you do the
adjustment.

Hmm, it sounds like it may be easier to send the lens with serious BF to japan country for calibration.......
I will loose the list ofcourse.....

And loose time to change setting each time I swap lenses... sounds gerat for portraits and studion work, but for outdoors shooting... dunno

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Lance B Forum Pro • Posts: 32,665
Re: K10D AF adjustment

janneman02 wrote:

Lance B wrote:

janneman02 wrote:

mskad wrote:

Yes. But it only takes about 3 to 5 seconds.

But you have to remember each value for each specific lens

Keep a list in the camera bag and refer to it when you do the
adjustment.

Hmm, it sounds like it may be easier to send the lens with serious
BF to japan country for calibration.......
I will loose the list ofcourse.....
And loose time to change setting each time I swap lenses... sounds
gerat for portraits and studion work, but for outdoors shooting...
dunno

See my post here. It's just a theory and I maybe completely wrong(as usual) but you never know;-):
http://forums.dpreview.com/forums/read.asp?forum=1036&message=22028088

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Eric H Regular Member • Posts: 150
Re: K10D AF adjustment

I agree that this focus adjustment menu is killer. I already fixed my general problem, and I suppose I could easily come up with a chart for indoor/outdoor shots with every lens. Pentax may 'accidentally' have a killer feature on their hands here if they can set the camera up to remember AF adjustment settings on a per lens basis. As has already been mentioned, the lens data (at least for modern lenses) should be communicated to the camera... it can't be that tricky to set these AF adjustments for each lens permanently. If they were configurable based on lens/WB combination, well that would be just about perfect. No more worries about front-focus or back-focus with any lenses in any lighting... the camera remembers miniscule adjustments for all conditions.

All manufacturers admit that stacking tolerances cause slight variations in AF performance between components... Pentax, whether intentionally or inadvertently, is in a prime position to actually let their users do something about it... and I couldn't be any more thrilled.
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Pete Fang Senior Member • Posts: 1,900
Re: K10D AF adjustment

mskad wrote:

I also noticed that the adjustment values are quite different if
it's under daylight or tungsten conditions.

I only tested the FA* 85 and the 77 Limited last night and couldn't do more as it was past midnight but I had similar findings. Under tungsten (incandescent) light, both lenses front-focus without calibration. Using the 85 at f/1.4 wide-open, I found that an offset of -140 um produced sharpest results on my K10D. I put on the 77 and found the results to be about as sharp at the same offset. However, the same lenses would back-focus under different lighting conditions. I tried focusing on the computer LCD screen and at the -140 um the camera definitely back-focused.

I did some quick test this morning before leaving for work. It seems that at the out-of-factory (or should we say "factory calibrated") "0" value, the 85 focuses alright in natural light near the window. I didn't have time to fine tune but I think it wouldn't need a large offset to get the best result.

PS: If only Pentax was willing to make this feature easier to use
through a firmware update, this could become THE killer feature
(Ideally and after calibration, the camera would automatically
adjust the offset based on a predefined value for each lens).

This ain't gonna happen but I agree it would be a killer feature. I'd be willing to lose the custom functions for an AF calibration + offset storage for 10 or 20 lenses.

Peter

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LuzArt Veteran Member • Posts: 6,643
Should firmware upgradeable?

Considering this is essentially a firmware feature (correct me if i'm wrong) this kind of lens adjustment memory feature should be possible by a firmware upgrade.

Ben
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janneman02 Forum Pro • Posts: 15,733
Re: K10D AF adjustment

Pete Fang wrote:
msk

PS: If only Pentax was willing to make this feature easier to use
through a firmware update, this could become THE killer feature
(Ideally and after calibration, the camera would automatically
adjust the offset based on a predefined value for each lens).

This ain't gonna happen but I agree it would be a killer feature.
I'd be willing to lose the custom functions for an AF calibration +
offset storage for 10 or 20 lenses.

How about putting this under a menu option that allows you to correct FF/BF with one of the scroll wheels??

IN theory we may get something like the AF override feature (darn, I forgot the name) on the DA lenses.... Let the camera do the focussing and then change according to your own needs..

Peter

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rennie12 Senior Member • Posts: 2,844
Has anyone done any testing comparing focus

under Tungsten using RAW as compared to JPG ? Since RAW does not really use WB I wonder what actually goes on here?

I also suspect a lot of FF/BF issues under tungsten may be related to really wide open fast lenses. I know my 77 LTD has a TINY DOF wide open - if you fill the frame with a head you better know which eye you want in focus if the face is 3/4 view - and since this is not a zoom you don't always have a choice of "how big!"

I would also love to see a comment by NedB on this - tho he seems pretty quiet since the takeover by Hoya...

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bill wilson

SFT007 Veteran Member • Posts: 5,872
Re: K10D AF adjustment

mskad wrote:

For the curious, here are "my" adjustment values (daylight/tungsten):

DA 21mm f/3.2 (+40/-20)
FA 31mm f/1.8 (0/-80)
DA 40mm f/2.8 (0/-80)
FA 50mm f/1.4 (-60/-120)
FA 77mm f/1.8 (0/-80)

IMO this is scary that the AF performance can be this inaccurate based on the lens. On the contrary to how you see this I think its terrible Pentax cant get the AF right. Sure its very nice having this option leaked (which we are not officailly supposed to have) and to be able to adjust it based on the lens and the lighting condition we are shooting in but this is obviously something that shouldnt work and be this way. The public should have no access to the Debug menu obviously and nor is having to change the settings everytime one has to change lenses very fun either. Sure its not hard but thats not the point. Also since 99% of K10 users will not know about the Debug menu option this seems like terrible performance by the SAFOX engine. At least thats how I see it.

BTW - I find that -120 to -140 (incandescent light/depending on lens) improves mt DA18-55, DA50-200, DFA100 and FA50 but messes up my DA10-17 fisheye which only requires a little adjustment of -50 or so.

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Sinan

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OP mskad Veteran Member • Posts: 3,329
Hi Lance...

I used CWB for my tests (and in general when shooting tungsten, even if I only shoot raw).

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OP mskad Veteran Member • Posts: 3,329
Hi Sinan...

A couple of things to keep in mind:

These are minimal adjustments. Most of the times, you won't see any difference with or without any adjustment either because of the DOF or the nature of your subject (on 3D subjects something will be in focus!).

It is perfectly normal to have lenses that behave differently (manufacturing tolerance, lens design, quality of the light, etc). Now what's remarkable is how consistant and accurate the Pentax SAFOX engine is: the K10D AF is incredebely reliable, once adjusted.

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SFT007 Veteran Member • Posts: 5,872
Re: Hi Sinan...

Yes you are right that when stopped down the difference is not as huge but still visible, once adjusted the thing is very good - I completely agree but when its not adjusted its pretty unreliable - in daylight its much better but sometimes I still find it misses focus, BTW - I do all my tests on real subjects - I dont like shooting test charts and I get a better idea of how the AF mechanism works when I try real subjects. If I get the chance I will test the AF out in natural light today with the adjustments and see how it fares, in good light I am likely to use a smallish aperture giving more DOF whereas in low-light I will use a larger aperture to gather in more light. I was very surprised by the good performance once set - its only that I wish Pentax could tweak the AF settings so that the AF mechanism would know what settings to use with each lens if that is possible. Or at least an option to remember settings for lenses. Still nice to have this debug option but its not a real alternative and now it seems the issue should be fixable with firmware as it seems all that is required is some programming (or so it seems).

mskad wrote:

A couple of things to keep in mind:
These are minimal adjustments. Most of the times, you won't see any
difference with or without any adjustment either because of the DOF
or the nature of your subject (on 3D subjects something will be in
focus!).

It is perfectly normal to have lenses that behave differently
(manufacturing tolerance, lens design, quality of the light, etc).
Now what's remarkable is how consistant and accurate the Pentax
SAFOX engine is: the K10D AF is incredebely reliable, once adjusted.

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Sinan

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Hythloday Senior Member • Posts: 2,177
Re: Hi Sinan...

Sinan Tarlan wrote:

its only that I wish Pentax could tweak the
AF settings so that the AF mechanism would know what settings to
use with each lens if that is possible. Or at least an option to
remember settings for lenses. Still nice to have this debug option
but its not a real alternative and now it seems the issue should be
fixable with firmware as it seems all that is required is some
programming (or so it seems).

There are hundreds of lenses, so it is impossible to remember settings for all those lenses. Should it store only settings of Pentax lenses, or also the settings of third party lenses?

I use 4 lenses with my Pentax K100D, three of which focus perfectly without adjusting focus correct. But my DA12-24mm did not focus properly, because it hardly reached infinity where it should. This was no problem because all focussing errors fall within DOF. Now that I have set focus correct to -70 my DA12-24m focuses perfectly.

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