Originally posted by wasim_altaf Lens is DA-40mm, shutter speed was generally high and shouldn't have required SR. I was using auto-focus, using both AF-S and AF-C mode. Actually, I was trying out focusing with the AF-button only, with focus-by-half-pressed-shutter disabled. Don't know if that had anything to do with it, however.
Focusing via the AF button with focus-by-half-pressed-shutter disabled should work fine, so that shouldn't be the problem.
Based on your samples I'd say the camera is back focusing as the water looks more in focus than the birds. It's also possible in AF-C that your composition momentarily shifted and the focus point was on the water or transitioning from the water to the bird or vice versa when you let off the AF button to stop focusing (though the water doesn't look in focus either).
I'd try to test your focus adjustment by doing something like this. Set the camera on AF-S and select the center AF point, so you're sure which point is being used. Set maximum aperture for the lens (wide open - ie, f/2.8 on the DA 40mm). Set up three objects with flat surfaces and fine detail (books, dvd boxes, filter cases, etc...) in a staggered line like this...
To detect a large error, you may need to increase the distance between the objects on the near/far axis (maybe one or two feet apart rather than inches as shown).
Then shoot 'em straight on, focusing on the middle object from about ten feet away.
If your lens is back focusing the object further away will look better than the center or nearer one, like this...
Properly focused, the center object will appear in best focus like this example (at a different focal length, but it shows what I mean
)...
To adjust focus on the K20D, you enter the custom menu, and near the bottom of the list is #35. AF Adjustment - activate that, and enter the "On" submenu, and here you can adjust your focus... "Apply All" is a global adjustment which will change how your camera focuses for every lens, while "Apply One" will be an adjustment applied to just that model of lens (ie. the DA 40 only). I found that most of my lenses needed -6 or -7 adjustment, so I set Apply All to -7, and I can go up and down from there as needed for an individual lens, but a new lens should be close without adjustment. When setting the adjustment,
- Higher adjustment numbers (+) move the focus closer to the camera
- Lower adjustment numbers (-) move the focus farther away.