I hesitated several weeks before buying a K20D because the manufacturer’s literature states that the camera retains the K10D AF system. Since I found AF to be the K10D’s biggest weakness, this gave me pause. I’m happy to report that the AF is not the same, and all to the better. First, AF action with the lenses I’ve tried is faster, crisper. (Pentax may still say the AF is the same: I’m simply reporting my impression based on tens of thousands of exposures with the K10D and now 519 with a K20D.) AF accuracy is also improved. The K10D focus points were too much like broad patches for my preference: aim at a flower in front of a wall, and it would focus on the wall. Hold your hand out in front of the camera and point the AF patch at it and the focus will be perfect, but hold up just one finger and the focus will snap to the backgrounnd. Not a matter of back-focus, it was just blind to narrow objects that I would expect AF to recognize. The K20D consistently focuses on targets the K10D would miss.

I shot three frames of this subject, de-focusing the lens between shots, and the AF, in single shot selective center spot, snapped onto the iron gate each time. The older camera would have invariably focused on the brick wall in back, requiring manual over-ride.

AF accuracy is further improved by a brilliant new feature: user-adjustable AF focus point correction. With the camera firmly mounted on a tripod, aimed at a focusing target (you can easily find one for download on the web) make several exposures, download to a computer and view at 100% magnification. If the focus is in front or behind the intended point, go into the camera’s menus and change the custom setting, then test again. Of five modern Pentax AF lenses I have handy, one required a hefty correction of +6 (out of a possible ten), one needed +2, another benefits from a tweak of +1, and two others are dead on the money as is. The camera recognizes the lens as you mount it and applies your custom correction factor. My understanding is that the camera recognizes the lens by type, not individual serial number so if, as in my case, the factor of +6 is set for my 21mm DA Limited, the same factor would be applied if I borrowed someone else’s 21, which would likely introduce an error. You can also set a factor for all lenses which in effect means a correction for the camera itself. Of course this feature is ripe for abuse. Careless or mistaken use of AF correction could easily ruin the performance of excellent equipment, so use with extreme caution. But oh boy, do I love this feature!

Speaking of quick and crisp, the new camera is rated for the same 3 fps sequence shooting speed as its predecessor, but the action feels faster and “tighter.” I almost never shoot sequences but I certainly want the shortest possible lag time from button push to shutter actuation. I don’t have equipment to measure this, but the new camera seems to release closer to NOW than the old one. It also helps when making a grab shot if the AF is fast and certain.

This is an example. I turned a corner, the delivery truck roared by, and I shot two frames, barely getting the camera to my eye. Auto focus, auto (program) exposure, just a little tweaking of the RAW capture in ACR.