K200D AF Adjust - Yes, it works!

Hey hey,

Was a little frustrated with my K200D and new Sigma 30 1.4. Was very noticeably front focusing at wide apertures, which I why I bought the stinkin lens anyway. After a few days of reading posts where most people said it didn't work, I found this thread and tried it myself - http://www.pentaxforums.com/forums/pentax-dslr-discussion/75223-k200d-autofocus-...

I also typed out detailed instructions on exactly what I did. Use at your own risk but it worked fine for me:

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

Was not aware of back focus and front focus issues. seems a very complicated process, is it possible to damage the camera?? I wouldn't know whether mine was FF or BF
How does a camera become like this, surely it comes from the factory ready to go.

Regards

Chris

Back or front focus issues are very much lens dependant and is not necessarily a problem as long as it is adjustable for each lens.

This is why in later Pentax DSLR models there is an option to adjust the focussing for 20 lenses individually.

A test chart or some careful test shots is required to determine if an issue exists at all.

Chris if you dig into Nathan's posts you'll find a link that explains how manufacturing tolerances on the body and on the lens can interact to make one lens look superb on a given body and another lens behave poorly.

However, good enough is good enough and if you are happy with your lens performance then there's no need to adjust. I was until I bought a lens that really didn't perform and I spent 3 hours adjusting for the best compromise for my most used lenses. The downside was that one lens that was superb became all but useless so I had to trade one lens for another.

I'll get a K20 or K7 eventually and all my lenses will be OK then.

Mike

Chris - Honestly, the process is NOT that complicated. I just explained every single step in detail. Step 2-6 takes about 2 mins total. Testing would have been much quicker too if I had a real test chart.

I don't think there is too much risk to bricking your camera with this one. There is much more risk when you're trying to upgrade firmware yourself. This "hack" is just a trick to access the camera's factory installed hidden setup features without needing official Pentax equipment.

You might not notice FF/BF unless you're shooting less than f2.0, because the depth of field from f2.0< is enough to compensate for slightly off focus points.

MikeW - I agree that all cameras should have individual lens adjustments. It's simply an addition to the software/firmware that wouldn't cost the Manufacturers a dime to immplement. Even if it was just 5 that would be fine for me. I think they exclude that feature simply to make you want to upgrade to the highest end models. LAME.

However for now, I'm going to buy two of the cheapest, smalled SD cards I can find to load the Debug Enable & Disable scripts onto. I'm just an amature shooting mostly friends, travel & sports - so I don't need to change lenses all that often, and if I do it doesnt need to be very quickly. That'll be a 5 quid solution.

If I could cram the Kx guts into the K200D body, add 5 custom lens profiles (w/ AF Adjust), add a prism VF and front exposure adjust dial, I'd be totally jazzed.

If only Pentax lenses are used, would that mean the camera wouldn't need tweaking? or indeed, being subjected to a "hack"

Regards

Chris

No - all lenses and bodies are built within acceptable tolerances that make them fit for the purpose but by no means perfect.

Let us say perfect is a zero value for lens and body.

The body in manufacture is allowed plus or minus 5 units as are the lenses as nothing is perfect.

Your body comes out +3 say. Within tolerance but not perfect.

You have one lens that is zero - ie spot on - it will probably look fine in practical use (I know my 35 mm f2 did) Boy and lens are +3

You have another lens that is -2 units. So on your body that gives 3-2=1 which would be even better and turn in excellent results. This is probably what happened with my Tamron 17-50 which was amazing.

But then you get a lens that is +4 which is within bounds but with your body is 3+4=7 and that is now sort of outside the ideal and may not work so well like my 30mm f1.4 did.

Now you have two lenses that are OK and one that isn't.

At this stage you do what muggins did and settle down to get the best compromise for the lenses that you use. Took me 3 hours to do 6 lenses and realise I could either have the 30mm 1.4 or the Tamron 17-50 but not both.

In adjusting for the 30mm lens I also improved the Pentax lenses I had, 35mm f2, 70mm ltd, 21mm ltd but the 50-200 wasn't so lucky and is a bit off but I barely use it.

I don't know if that helped but you do have to accept that all bodies and lenses will come off the line around the ideal but rarely hitting the exact value you'd want.

mike

Good explanation Mike.

And dont forget that last but not least - you can send your body & lens to Sigma UK and they'll calibrate the lens to your specific body - FOR FREE if you're still in warranty. That way, you can do the AF Ajust to get it as close as possible for all the Pentax lenses, then send the body & lens off to Sigma to adjust the 30f1.4 to your body.

Fella at Sigma UK said it would only take about 2 weeks. Some dealers may even pay the shipping for you.

Mike, thanks for the very good explanation. I had no idea about all this.
So either you adjust the body to suit one lens over another or live with the shortfalls that all lenses seem to have and live with the compromise.
So , I could set my camera to work best with my favourite lens? I dont know whether I fully understand yet:My two favourite lenses--55-300,FA50, if I get one to work at it's optimum, that will affect the other-correct?

Thanks for help so far
Chris

But if they calibrate the body to a lens then they'll potentially screw it up for the other lenses (I imagine). If they only adjust the lens then you're OK.

I fear that everything in life is a compromise and I can't recall what the figures were for my lenses but for all but the 17-50 they were all back focussing a bit and all improved after adjustment by varying amounts. I do use the motto - good enough is good enough - but I would still like the K20D's ability to have settings for 20 lenses!

Mike

Yup, Sigma would only adjust the lens as they can't technically mess with a non Sigma product. I think there is some sort of mechanical adjustments that Sigma can make to the different lens groupings to correct IN THE LENS.

So if I really wanted everything perfect, I'd send in my new (not even bought yet) Pentax Kx and Pentax Lenses to a Pentax shop first and get them all calibrated togeather. Then, I'd send the Kx and Sigma lenses off to Sigma, and they would adjust only the lenses to match the body. Everything in harmony and the world can turn again (and by the time that was all finished, the K8 would be out!)

I do wonder where the whole subject of calibration leaves the novice or keen photographer, surely the majority wont be aware of this adjustment process.I imagine that most people will be able to live with the factory settings.?? There is talk about sending off Sigma lenses for calibration but not other makes of lens.I'm left wondering whether this process will wind me up and make me dissatisfied with my gear. I wonder what Pentax think about it all??:

Regards

Chris

The only question that matters is 'am I happy with the quality of the images I produce' and don't measure that by pixel peeping. Look at the photo and see if you're happy. If the focus is always off and it shows as it did with my 30mm f1.4 then do something about it - get another example of the lens or adjust. I wanted to use that lens so I invested the time. Otherwise I was happy with the performance of my lenses up to 12x16" prints so didn't bother.

Just take photos is the real answer and then address any issues as they arise

Pentax along with all other manufacturers must be aware of these issues and addressed them in the K20D/K7.

Mike

Mike, thanks,I'm starting to understand more.

Regards

Chris