[Super A]

I've noticed on different occasional that I've gotten a few slightly out of focus portrait shots from my K20D set on manual focus on a tripod. Shake reduction is turned off. It's happened with a 50 A 1.4 and a 24 A 2.8. Most shots are sharp, but occasionally one or two are visibly slightly out of focus without having touched the camera or tripod. I can't explain it, other than maybe there is an issue with the sensor. Has anyone else seen this happen?

[JeffJS]

I've noticed on different occasional that I've gotten a few slightly out of focus portrait shots from my K20D set on manual focus on a tripod. Shake reduction is turned off. It's happened with a 50 A 1.4 and a 24 A 2.8. Most shots are sharp, but occasionally one or two are visibly slightly out of focus without having touched the camera or tripod. I can't explain it, other than maybe there is an issue with the sensor. Has anyone else seen this happen?

Anything is possible.. The first question I'd have, is the tripod on stable ground? Or is it on a floor that moves, even slightly, when you walk around? Being a heavy guy, I've noticed, particularly with longer exposures, that if I move around the shot will blur somewhat...

[Mike Wise]

I guess another possibility is that you didn't focus the lens precisely. It is, after all, manual focus. I know that some of my manual focused photos aren't perfect. I don't use any add-on for focus, like a Katz-Eye. It might help you, if you don't.

[iCrop]

You're using a couple of fast lenses there. Make sure to close down the aperture a bit to give you some depth of field to work with, and a split focusing screen helps a lot to verify focus. Other reasons might be that the subject moved and you're using a slow shutter speed. Also use a remote release (cable or infrared). I hope this helps...