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01-06-2009, 03:46 PM   #1
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K100D Super AutoFocus Problem

It looks like my K100D Super is slightly front-focusing when I enable AutoFocus on my SMC DA 19-55 and my Sigma 70-300 (Or select "Enable FI with S Lens used" option on my Cosina 50/1.4). I can roughly say that the deviation is almost the same with all lenses. When I perform this test using manual focus, I seem to have no problem at all.

Is there a way to calibrate the K100D Super or should I go for the authorized service center? (The camera is still under warranty)

Thanks

01-06-2009, 04:55 PM   #2
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QuoteOriginally posted by oguzgel Quote
It looks like my K100D Super is slightly front-focusing
Is there a way to calibrate the K100D Super or should I go for the authorized service center? (The camera is still under warranty)
Before doing either just double check on another day and under different conditions to be sure.

eg: I believe a lot of dSLR's have problems focussing in yellow light.

If you are sure you have a problem - and since the camera is under warranty - speak to someone at Pentax and see what they say.

If you are willing to try your hand at it - one can make AF correction adjustments - I think the K100D Super has the same firmware as the K100D? the most current is 1.02?

If so - take a look at this thread K10D focus issues (page 2) - I know it says K10D but there is quite a bit about the K100D calibration, and a link to yellow light focussing problem.
01-06-2009, 11:56 PM   #3
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As for trying calibration, K100D Super does not have the same firmware as k100d had. It is impossible to enable the debug mode with key combo, as with k100d . It is possible to do so with a special software trough USB, after adjustments it can be disabled in camera as with k100d. (Btw, tried with my Sigma 30/1.4.. no use, still backfocuses-Adjustment when misses, +FF Adjustment when its "correct"). ...On your own risk!!!
You can find links to the software and description in here:
RiceHigh's Pentax Blog: K10D Firmware 1.3 Debug Mode Unleashed
Same software mentioned few posts previously:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/44804-k10d-debug-m...us-issues.html

Last edited by ytterbium; 01-07-2009 at 11:19 AM.
01-07-2009, 02:18 AM   #4
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Thanks very much indeed for the replies. I performed the same test using the famous "Focus test chart" that is available over the net today with the following differences:

1 - Removed UV filters on my lenses
2 - Performed the test under bright sunlight at the balcony

Here are the results, of course dependent on my subjective perception with my eyes:

1 - Sigma 70-300, Both on 70 mm and 300mm, AF enabled: OK
2 - DA 18-55, Both on 18mm and 55mm, AF enabled: OK
3 - Cosina 50mm f/1.4, Manual focus using the eyes : OK
4 - Cosina 50mm f/1.4, "Enable FI with S Lens used": Front Focusing

It looks like I will learn to live with it by not using the "Enable FI with S Lens used" option and contiune relying on the AF system on Pentax and Sigma lenses as I do not think that an opportunity of calibrating my 25-year old Cosina lens for the Pentax K100D Super AF or calibrating the AF system on the Pentax K100D Super particularly for this lens exists, nor I believe Pentax autorized service center assumes such a responsibility although the camera is still under warranty.

Again, sincere appreciation for the replies and would like to hear if I could have more options.

01-07-2009, 10:20 AM   #5
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QuoteOriginally posted by oguzgel Quote
2 - Performed the test under bright sunlight at the balcony
very cool! glad you found your K100D Super's AF focussing was OK.

Now you might want to try the acid test of focussing under tungsten/yellow-biassed light,
and see if there are any errors/anomolies that you might want to be aware of under those specific conditions.

RiceHigh's Pentax Blog: AF Accuracy's Dependency on Lenses and Yellow Light

dpReviewForum focussing issues under Tungsten light

Last edited by UnknownVT; 01-07-2009 at 10:26 AM.
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