Originally posted by JeffB What body are you using? AF mode? AF points? On K-5IIs and K-3 my 60-250 does not behave like that. Totally possible your lens is having function trouble but I'd suggest trying all combinations of AF modes and AF point selection to see if the bad behavior is consistent with all camera settings.
Originally posted by Na Horuk Yep. Is this AF.S, AF.C, Auto-select 11, Single point, Live view? And which camera? Was the lens modified in any way, does it have a filter mounted?
Focusing in big steps is not completely normal, but it really depends on the scene, light, contrasts.
First things to do is make sure lens mount is not damaged, not dirty. Then check front and back glass of lens. And remove any filter. Then you do a systematic test in good daylight with a big, contrasty subject and AF.S, single point. Switch to MF to defocus between test shots. Best to use tripod, 2 sec timer, lowest ISO.
I thought you'd notice that it's a K3ii. Tried ALL autofocus modes and points. This problem is occurring outside in strong light, from iso 100 on up. No problems with any other lenses, including screwdriver DA limiteds, a 10-17 fisheye, and the 16-85. Focussing on a strong scene with lots of verticals/horizontals/diagonals in distance and up close - nothing 'tricky. It goes 'brap brap brap brap' and focusses in stages from near to far, but goes directly onto the subject from far to near. Very strange. I think it has to go back.
At what point do we declare it a lemon? Optically, it is magnificent, but this focus problem sucks.
Cheers,
Cameron