I've been toying with this new features since a few days (I got my K20D 2 weeks ago). I tried to use focus charts at 45° but I've been frustrated by the inconsistant results.
I've tried this:
-
Nikon D70 Focus Chart
- The special chart by Yvon Bourque
-
Jeffrey Friedl’s Blog Jeffrey’s Autofocus Test Chart
-
AF microadjustment for the 1Ds mark III and 1D Mk3
-
ISO 12233 Test Chart
The last one I liked best. I don't think I like angled test charts that are not always easy to interpret correctly at least on the LCD screen. With the parallel to the focus plane charts, I can do tests shots and compare them at high magnification quickly.
My adjustments so far:
- FA50/1.4: -10 ! Now I will not say that this lens is very soft wide open. It's still not tack sharp but it's hugely better now.
- DA40/2.8: -4
- FA77/1.8: -5
The zooms were mostly correct and didn't seem to need adjustments. But they also are usually much darker and thus maybe their DOF mask any AF inacuracies.
Now I wish it would be much easier to correct the lenses. Not easy to see the difference between -1 and -2 for example. A fool proof method that Pentax could offer is:
- let us download and print a test chart (or include it in the box)
- AF the chart, then manually focus the chart (with a better liveview, it would be easy)
- The camera would then compute the difference and set the adjustment number automatically
Also, I think +/- 10 is maybe not enough. Other camera makers offer +/- 20 adjustments. The "Apply to All" should be cumulative and should be seen as correcting a body misalignment.
At least this feature improves the performance of some lenses, especially the wide aperture primes.
Here is the FA50 examples shot at f/1.4:
Unadjusted:
Adjusted: