Lens calibration shop

Schnitzer, I think I may have found the answer to your problem. Back in the day on the K-10D the only way to adjust AF was in Debug mode. This involved creating two text files on a clean CD Card and switching the camera on with the door open IIRC.


You get an extra menu called test mode





and you use the sub page AF TEST and change the values in Focus Corr.





That's exactly how I did it in the K-10D. You just need to change the valie to place all your lenses within the +/-10 range in the regular menu


Those are Screenshots from the K-3, you'll have to read the thread to get the numbers of the files for the K-50


http://www.pentaxforums.com/forums/6-pentax-dslr-discussion/250555-resurrecting-pentax-firmware-hacking-3.html

thanks mate.appreciated! i'll give it a read

I'd always found that to be a hit-and-miss affair with manual lenses both on the K-7 and K-5ii. A good focusing screen is much easier.[/quote]It's actually very accurate, but you have to know more about what
is meant by and how to focus a camera. I've seen Canikon users who
seem to understand but Pentax users expect it all to be automatic
and the camera do everything.

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so educate the masses then!

Post a spoiler you mean
Then I would have people complaining that they had been trying
to figure out the green dot since the ME-F came out 32 years ago
and they would have nailed it in another year

This video might give you a few hints.....
http://www.youtube.com/watch?v=7zE50jCUPhM

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With CiF what do you do when the bit of the image that you want in focus is not at your chosen focus point ?

Press shutter half-way.
Move in until you get a beep and CiF lit.
Re compose.
Shoot.

If you look at the video you will see that there is a CiF range
just like a DOF range. I set mine up with an adjustment value so
that as I move in on a bug the shutter trips at the beginning of
the range.

Easier to set up using a focus rack with a mm scale on it and a
lens that performs well wide open.

Some notes from a FA 50mm f/2.8 Macro on a K-5
Daylight LED lighting
Distance sensor to target 770mm
Rack at +/-0mm is in focus.

+2 Adjustment set on camera
Beeps at -7mm and +9mm so +2 is OK for general/stopped down use.
For more accurate focus set rack halway between the two values.

Change Adjustment for it to trigger (CiF) at -7mm and fire as
the camera moves in. +5 Adjustment seems OK.

Note: The beep/green light works with any lens with the
camera set to MF. CiF only works with MF lenses or lenses
with a MF/AF switch and the camera set to AF.S


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That is not CiF, where the shutter fires automatically when focus is detected

CiF works exactly as defined on page 136 of the K-5 manual so
what you are talking about isn't CiF

I think we are splitting hairs which seems to be
the norm for this forum so I'm finished with this
thread.

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Well after some tests it seems that +10 is not consistent throughout all the apertures or focal distance. For instance at a close distance and F/4 the setting needs to be at +10 whereas at focus to infinity and F/11, i get better results with +4 than with +10.
Is this common?

You'll find various recommendations/suggestions for distance to target, but generally, test (a) wide open, and (b) if a zoom, either at your preferred focal length or the average of three readings taken at shortest, middle and longest ends of the zoom's range.

Unfortunately we don't live in a perfect world and calibrating a zoom is at best a compromise. I always aim for an 'average' focal length and get it right for that.

Regards
David

I still can't understand why people get obsessed with 'calibration'. With DA lenses all the relevant focusing parameters are in the lens EEPROM - read the patents - and so far no-one had figured out what they mean.

All that the menu 'calibration' tweak does is correct for tolerances in flange distance of a particular lens or of a particular camera.

That's exactly why we do it. I have a DFA 100 F2.8 macro WR that would be useless if I hadn't calibrated it. It needs +10 adjustment as without this it back focusses badly, not desirable with a macro lens! I can't get it sorted under warranty as I bought it second hand and I suspect that the previous owner couldn't get a sharp image from it. Now that it's calibrated to my camera bodies it works perfectly.

I'm not 'obsessed with calibration' but I do want my expensive equipment to deliver the results I expect from it. Pentax wouldn't put AF adjustment menus in their cameras for no reason and they wouldn't have even greater adjustments available via the debug menu either if everything was perfect from the factory.

Regards
David

I'm not obsessed by it, I just want a subject to be in focus when the AF says it it's in focus. Simples.