K10D+43mm F1.9 Limited Problem

Hi Everyone,

I am a new comer with a question. Recently I bought a used 43mm f1.9 online, and I found with this lens my auto-focus on K10D is not working very well but with my others like 16-45mm f4 it is all right. So I am wondering if there is a problem with this lens or this is normal for the combination K10D+43mm f1.9. Or other possible problems?

Thank you.
Peng

What do you mean by "not working very well"?

Could you be more specific?

In what way is it not working very well? A good first step would be to do a focus test to identify exactly what the problem is. Download a focus test chart - the one on www.focustestchart.com is the best - and follow the instructions. Using a tripod helps if you have one.

Then post the resulting images on here, and someone should be able to identify the problem.

I've had to calibrate the AF on my K10D in debug mode to get accurate AF with my lenses.

I use a K10D and FA43 and they work fine together, I have calibrated the AF on the camera though.

My K20D didn't need calibrating for any of lenses until I got a DA* 50-135 recently and that needed a -9

My K10D however was way out @ 0um for everything and most lenses need +210um and the pentax 10-17 needs +130um

Sorry for the vague description.
It is out of focus, and 'the focused point' is obviously not clear.

Thank you for the reply.
But the firmware of my K10D is 1.31, so how can I be in debug mode? I heard only with 1.1 right?

My version is 1.3

Create a text file called MODSET.TXT in the DCIM folder of your SD card that contains the following

[OPEN_DEBUG_MENU]

Turn the camera on with the SC card door open. Close the door. you'll see a debug menu. Here you can enable debug mode.

Goto MenuSetup and scroll up to enter the Test mode. then enter AF TEST, ignore AF area test and scroll down to alter AF calibration in 10 um steps.


I leave my K10D permanently in Debug mode now, so I can alter the calibration when I put on a lens that needs it.

I have to say the default setting of 0um was way out of focus on my K10D. I suspect that's why the previous owner sold it.

I calibrate my AF by taking 37 tripod shots of a number plate ( aperture wide open for shallowest DOF ) in the street about 30 or 40 feet away, from 0um to 360um (10um steps ), each time letting the camera autofocus from nearest focus.

I then load them into Lightroom and find the sharpest shot and then set the camera accordingly.

Hi Smeggy

I tried this afternoon. I can tell the txt file has to be written in windows (notepad) not MAC (text editor), or you can not enable debug mode. That was a good start

Then I followed your instructions to calibrate my AF, and +80um was the one for me. However, it is really hard to compare some adjacent settings. So I can't say I have got the best one. So normally how much error is acceptable, 20um?

Another question is do I have to do so for every single lens? Calibration is for camera itself or different lenses on the same camera?

Anyway, I have better AF on this lens. Awesome!

Thank you.
Peng

Unfortunately, with the K10 the calibration affects all lenses, so you might now have to check the others. If they are off now, you might have to settle for some compromise.

Yes, I just tried another lens- -! back to 0um.
Now I fully understand why Smeggy left it in debug mode permanently.

Nice one.

Yes I found that a few adjacent shots were pretty much in focus. I chose the final setting by selecting the centre one.

And yes as said it affects all lenses. Just leave it in debug mode and change AF when you change lenses. It's a PITA but better than OOF shots.