I mostly shoot manual with my K-50, and I have had a lot of trouble with catch-in-focus and AF confirmation giving me blurry images. I decided to attempt to fix the problem by doing AF fine adjustment under "apply all" while using a manual focusing lens on a focus chart. The lens I chose was an old 50mm f2.0 k mount and all shots were taken wide open. The tripod was leveled and aligned precisely with the focusing chart, and I tried placing the chart and different distances to see if it affected results (it did not).
What I found was that the camera consistently front focuses rather severely. Moreoever, tweaking the AF fine adjustment settings had no discernable impact on the problem. As an experiment I tried dialing all the way to +10 and back down to -10, but the results were the same. Most of the time I did not use CIF, as I think other variables probably effect those results. Instead I dialed in focus until the green hexagon lit up, then snapped my pics using the self timer. The camera continued to front focus badly no matter what settings I used. This particular lens only works in manual mode with the green button programmed to TvShift for stop down metering, though I don't see why it would matter what mode I use for purposes of focus calibration. Of all my manual focus lenses it's the newest and in best condition, so it seems like the one to use.
I can only think of three explanations:
1. The fine adjustment range is too narrow - I know that in some cameras you can dial it to 20 in either direction, whereas the K-50 tops out at 10;
2. Whatever algorithm the camera uses to decide when to illuminate the green hexagon is unaffected by "apply all" AF fine adjustment;
3. There's some other variable I've failed to account for.
Appreciate any suggestions/feedback. I can get perfect focus in live view, but I would really like to not have to depend on live view so much when composing my shots, especially since I can't do CIF in live view.
Last edited by jimmypage; 11-16-2020 at 07:59 AM.