AF Calibration on the K20D

I have read in previous posts as follows:

"My AF was out, I took it to the camera store and he recalibrated it"

"Hacking into the Firmware to recalibrate the AF"

Now I downloaded the hacking "DEbug Mode" info. I wouldnt consider myself as a novice in regard to computers and software, but I found the hacking info really hard to follow.

As far as the camera guy recalibrating the AF, it seemed as if it took five minutes.

Just how is the simplest way to check and complete a recalibration of the AF.

Might need relatively simple language.

Hmmm you don't need to hack your k20D at all, AF Calibration is standard feature on the K20D.
Read the manual I would say.

The check your calibration there are some tests chart you can print out or some use some Lego
Put the camera on a tripod and make sure you've something with a lot of contrast to focus on and simply adjust it till it nails the spot.

With the K20D you can calibrate the camera for up to 20 individual lenses I believe, so you can calibrate all your lenses.

You don't have to use Debug Mode to calibrate AF. Item 35 under Custom Settings in the menu is AF Adjustment. Here you can adjust the AF in +/- 10 steps, either for all lenses, or individually for up to 20 different lenses (applies to the K20D).

As long as the camera can uniquely identify a lens, it can save AF setting for this lens, and automatically apply the correction whenever that lens is attached to the camera.

The Debug mode gives access to the Debug menu, where, as I understand it, a global basic AF correction can be applied. This setting then comes in addition to the individual settings in the Custom menu.

OK Stefan, you beat me to it

But you had more information in your comment that i later added... so does that make us even?

When you adjust the focus, you should always work with the diaphragm wide open (smallest f: number) to make sure your results aren't "screwed up" due to depth of field.

As said AF calibration is a standard feature on the K20D.

however invoking the Debug menu is very easy. simply write a text file called MODSET.442 into your DCIM folder on the SDHC card. The file should contain the text [OPEN_DEBUG_MENU]


Then switch the camera on with the card door open. You see the debug menu appear where you can then enable debug mode.

This is for firmware V1.03 - Simples.

Same for K10D but it's MODSET.TXT

Haha, I was using custom 35 as a sharpness enhancer, instead of under function - sharpness. No wonder I was getting soft focus.

I'm afraid that is not correct. The MODSET.442 file should be in the root folder of the card, not in the DCIM folder. There is some more info on the Pentax Hack website

Smeggy maybe that was your problem with the DFS hack that I posted

I'll try again in a minute. I remember originally writing it to the root and for some reason it didn't work so I then move it to the DCIM folder.


Back in a bit

OK, I must have had a brain fart. Sorry for above wrong advice. It should be in the root. I'll retry the DFS hack ....

I bought a Pentax 55-300. The focus is just so much better. But I havent given up on the Sigma 70-300 APO yet. I bought a focus chart, and will perservere a little longer. May be keep the Sigma as a second lens, for those bad weather days.

Regarding AF adjustments on the K20 - perhaps the K7 as well - The AF adjustment through the MODSET function adjust the AF globally.

I have one lens that I could not bring into focus through the function settings. All of my lenses needed a + 9 or better to bring them close to accurate focus.

I used a manual focus lens to adjust the MODSET AF adjustment and then went about adjusting all my lenses through the custom function. Now they are all within plus or minus 4!

Bob Rapp

I've just had to do this with my K20D. I recently purchased a manual focus 50mm/1.2 which the K20D's +/- 10 wouldn't accommodate. I had to go into debug mode on the K20D and set it to -250um for the manual lens to caliberate it's focus

This caused another problem. The 17-70 andn 135-400 sigma lenses now needed more than +10 so I had to compromise with the 50/1.2 and set the overall AF on the K20D to -100um too allow those sigma lenses to work at +10

At -100um the DA* 50-135 AF'd at 0

Conclusion: +/- 10 is not enough a rnge to cater for all lenses.