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10-02-2009, 04:10 AM   #1
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K200D autofocus fine tuning.

make a text file in the root folder of SD card.
name it MODSET.445
type the following in the text file.

to enable debug mode.
[DEBUG_MODE EN]

to disable debug mode.
[DEBUG_MODE DIS]

put the SD card in the camera
leave the card door open!

Power on while holding the menu button.
camera enters debug mode.
press menu button again.
go to setup menu (right arrow twice)
looks normal!!
press up arrow once
go to AF TEST
voila!
adjust AF compensation.
negative for front focus
positive for back focus
Mine needed -60um

run debug disable.

[DEBUG_MODE DIS]

put the SD card in the camera
leave the card door open!

Power on while holding the menu button.

cheers.
kris.

10-02-2009, 08:27 AM   #2
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Isn't this just a bit risky? Another question: is it possible to do some AF lens corrections in this way? (But I suppose even if it was possible, it wouldn't be possible for more than one lens.)
10-02-2009, 08:45 AM   #3
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Aha! I had tried this a few weeks ago when I first saw the instructions on accessing debug mode, but I was looking for the AF adjustment on the debug menu itself, and no one seemed to know where I should instead. Thanks so much for pointing out that I need to look for it on the Setup menu! Not that I'm having any problems, but still, nice to know.

BTW, Stefan, not sure what you mean by doing "AF lens corrections". That's exactly what this is, although as you say, it looks like it won't allow for different corrections for different lenses like some models do.
10-02-2009, 08:52 AM   #4
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Marc, thank you for the clarification. I imagined there was some lens-independent standard--quite stupidly, because any measurement would have to be mediated by some lens. My K200d's focus is right on sport with two lenses and slightly off (back and front) with two others. I'm inclined to say the latter two lenses are off, not the camera. But then is this AF correction method easy enough to repeat it whenever I decide to change lenses? Well, perhaps not 'whenever', not in the middle of the action, but before going on the field.

P.S. AF lens correction is what I envy most about K20D and K-7, even before the sensor's quality and certainly before the convenience of AF points.

QuoteOriginally posted by Marc Sabatella Quote
BTW, Stefan, not sure what you mean by doing "AF lens corrections". That's exactly what this is, although as you say, it looks like it won't allow for different corrections for different lenses like some models do.


10-02-2009, 09:37 AM   #5
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Is it possible that the lenses that don't show a problem have wider DOF (smaller maximum aperture, shorter focal length) and that is simply masking the problem that the other lenses are showing? If so, you should be able to safely do the adjustment for the lenses that do show a problem without affecting the others. I tend to believe that most AF problems would be caused by a misaligned focus sensor (not at correct distance), as I can easily understand how that would lead to problems. Such problems would of course affect every lens, although you might only *notice* it with lenses that have a very shallow DOF. I'm not saying other types of problems aren't *possible*, but explanations of how they might occur always strike me as only slightly more plausible than astrology.

BTW, I'm also not sure what you mean about "the convenience of AF points" - the K200D is no different from the K20D or K-7 in that respect that I am aware of.
10-02-2009, 09:59 AM   #6
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Sorry, Marc... I haven't slept much last night, and yesterday I read previews of and comments about K-x... It seems such a good camera, I was considering going from my K200d to K-x in the more or less near future. So, I had K-x in mind when talking about AF points.

Actually, it is mostly my lenses with narrower possible DOF (max apertures 1.7 and 2.8) whose focus is correct.

QuoteOriginally posted by Marc Sabatella Quote
Is it possible that the lenses that don't show a problem have wider DOF (smaller maximum aperture, shorter focal length) and that is simply masking the problem that the other lenses are showing? If so, you should be able to safely do the adjustment for the lenses that do show a problem without affecting the others. I tend to believe that most AF problems would be caused by a misaligned focus sensor (not at correct distance), as I can easily understand how that would lead to problems. Such problems would of course affect every lens, although you might only *notice* it with lenses that have a very shallow DOF. I'm not saying other types of problems aren't *possible*, but explanations of how they might occur always strike me as only slightly more plausible than astrology.

BTW, I'm also not sure what you mean about "the convenience of AF points" - the K200D is no different from the K20D or K-7 in that respect that I am aware of.

Last edited by causey; 10-05-2009 at 03:30 PM.
10-02-2009, 02:24 PM   #7
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Original Poster
You can leave the camera in debug mode. Other than the annoying notation of "debug mode" appearing at the upper left corner, there doesn't seem to be any other side effects. Everything works as before. You can predetermine the amount of correction each lens needs and either try and remember or use a gold marker pen and write it on the body of the lens. You can adjust in a jiffy. Eventhough K20D (which too I own), can store up to 12 lens corrections, most recreational photographers are not going to carry that many lenses. Moreover, as Marc pointed out, this problem is likely to be apparent in lenses at wide appertures. I don't know if there is a hack for adjusting lenses. In my case adjusting AF by -60um, made a huge difference.

cheers

kris
10-02-2009, 03:49 PM   #8
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Thank you very much, polur101. I'll try it in a few days.

11-03-2009, 05:05 PM - 1 Like   #9
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Confirmed - it works

Holy-sh*t-house-mouse, it works. AF adjust on the K200D.

Noticed some significant front focusing with my new Sigma 30 f1.4. A bunch of my pics from our friends Halloween party were OOF, but a few accidental shots were dead sharp, so I new it was just calibration. Ran the above commands but accidentally set it to -120 first time and WOW what a difference. Retested & trimmed that back to -50 and I think I'm good. Need to do some field testing next time I go to the pub for some low light portraits but after a few days of researching I'm happy this actually works .

Notes for newbs running PCs, as I'm a complete newb and this took a few tries to figured it out

1. Completely unscientific calibration test
I just used the Pentax quick reference guide as a testing plane instead of buying a thermometer like some others have suggested. Opened to a page with a bunch of text but with a line or two of open space in the middle. Wrote "FOCUS" with a Sharpie in the empty space with some cross hash marks to the left and right. Had the camera on Gorillapod about 6 inches high and the focal point about 2 feet from the end of the lens.

Make sure you're on single point center focus and the widest aperture you've got. Snap a few pics and see if the "FOCUS" and hash marks are in the center of the in-focus area of the picture. Before adjusting mine, it seemed that the "FOCUS" was blurry but a few lines of text in front of it were tack sharp = front focus (the actual in-focus zone is in front of where the camera thinks it is).

After making adjustments, I'd walk around the room shooting things that would obviously show FF/BF to check my calibrations. Few pieces of Halloween candy on my kitchen table at slightly different distances was a good test. Also tried shooting close to (within 5 feet) and further (across the room about 10 feet). Repeat the test and the steps below few times until it's satisfactory.

2. How to make Text File
Insert the SD Card & Reader into your computers USB and open a window for the SD Card through My Computer (mine was "Removable Disc H:"). Right click over the empty space on the right side of the window, which brings up a menu. Scroll mouse down to "New" which brings up another menu and towards the bottom is Text File (or Text Document for me in Vista). Click Text Document and badda-bing, you've got a fresh Text Doc.

3. How to edit Text File / Text Document
The new Text Doc will be named "New Text Document.txt". Open & Edit the text document before renaming it! Open up the Text Doc and type in exactly [DEBUG_MODE EN]. Close & save (automatically prompts you to save in Vista). Right click the Text Doc icon and rename to "MODSET.445" (no .txt at the end). A warning will probably pop up asking if you're sure you want to continue - click yes.

4. How to run Debug mode
Enter the card back into the cameras SD slot, but do not close the door. Hold down the Menu button and turn the camera on. It should display two version numbers (mine were both 1.00.00.02), the screen dimly flickered a few times, then everything shuts off... scared the crap out of me the first time ! Turn the power switch back to OFF and shut the card slot door. Your camera is now off but in DEBUG mode.

5. How to find and adjust AF Adjust
Turn the Power Switch back on (no need to hold Menu). The screen will flicker a little, then just show a blank dark glow. Press MENU - brings up the menu screen which looks pretty normal. If you scroll through all of the tabs, you'll notice some extra adjustments that aren't normally there...sneaky! Click the Right Button twice to highlight the Setup tab. Press Up Button twice (or Down Button a bunch of times) to reach "AF TEST", then click Right Button to open the AF TEST screen. First is AF Area Test with options of 0,1,2,3. I just left it on 0, not really sure what this one does. Click the Down Button to highlight "Focus Corr" to correct the focus. Left for Front Focus and right for Back Focus. Try going +/- 50 or 60 to start with and test/retest a few times from there. Press OK and you're done adjusting (at least this round), and turn the Power Switch back off.

6. Exit Debug mode back to normal operating mode
Right now, your camera is still in Debug mode so every time you turn it on, it will still be in Debug mode and you can't take pictures. Take out the SD Card, pop it back in the computer and open up the SD Card Window. Rename the "MODSET.445" Text Document to "MODSET.445.txt" (and click YES if the warning pops up again). Then open the Text Doc, delete the previous text and enter exactly [DEBUG_MODE DIS]. Close & save, then remember to rename the Text Doc again, back to "MODSET.445" (no .txt at the end). Plug the card back in the cameras SD slot, leave door open, hold menu & turn on. The screen will flicker, show those two version numbers and then go blank again. Turn the Power Switch off. You're out of Debug mode and back to normal.

However I would go ahead and remove that text file, not sure if its the best idea to leave them on the card but that's just a guess. Might be a good idea to buy two tiny SD cards, one with Debug Enable and the other with Debug Disable prompts on them, so you could adjust in the field without a computer ?!? Each file is only 16 Bytes...hahah.

Try this at your own risk, but I hope this detailed account of my experience helps.
Mugs
11-05-2009, 08:58 AM   #10
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Thanks much guys,

Now as far as I understand, we will have to remember the adjustment scores of the each lens, leave the debug mode on all the time and change amount of correction whenever we change the lens, K200D can't remember the each lens correction, just as in K20D or K-7, is that right?

Also would someone point us how to calibrate lenses more scientifically, or mostly used proper method please.
02-19-2010, 06:26 AM   #11
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Very informative.
So what's the real deal on carrying out a proper AF focus test?
I have already done some measures, although it was in tungsten light and I read this can also slightly implicate improper results my K200D shows slight frontfocusing.
However these testcharts are designed to show pixelperfect results at very shallow DOF, real life shootings I do not experience misfocusing. To reach the shallow DOF I tend to manual focus my lens anyway, and this method, even on testchart is spot-on perfect.

Any thoughts are welcome here.
02-19-2010, 09:30 AM   #12
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If it ain't broke, don't fix it.
08-10-2010, 11:36 PM   #13
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I have used this procedure today on my K200D with v1.1 of the firmware installed. It all worked perfectly. Thanks for the original post.
08-11-2010, 04:03 AM   #14
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Wow, I had no idea you could do this on the K200D! Shouldn't this be a sticky somewhere?
07-22-2011, 02:21 PM   #15
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Old thread, but wondered if anyone had thought of creating a picture file on their K200 which contains the text notes of the adjustments forveach of their lenses?
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