Adjusting the HD DA* 16-50

Does anyone know of any good resources for adjusting the focus of the 16-50 on a K-3iii? Mine has terrible front focus and it's driving me nuts as I have had to bin too many photos. If I use live view and manually adjust the focus it can be as sharp as a sharp thing, but the AF is often out. The live view quick-shift is fine when I'm using a tripod but not viable for quicker photos. I did wonder if it was a problem with my new-to-me K-3iii but images with the 31 and 77 ltds are fine so I need to play around with the focus adjusting feature.

Thanks, Kris.

Focus adjustment is all down to the body I believe. Sometimes a lens can have an issue with forked contacts that transmit focal length FL information and this causes problems with focusing. Symptoms include racking AF without correctly locking.

Check to see the FL that the lens reads out corresponds to the FL on the lens zoom ring. Use the quick select menu with the FL adjust (on Info) to make it easier to see how the lens reads out as you turn the zoom ring.

Also, as a side point once you've tweaked the fine focus it should be perfect on that specific focal length. There may be slight shifts at other focal lengths (i.e. +4 on one FL, +7 on another).

If the other lenses are perfect then it won't be something like a dirty AF submirror.

Have you tried fine focus yet? Sorry for the almost incoherent message.. I'm throwing out ideas!

It was tips on using the fine focus I was after. I rambled a bit in my original post, sorry. Is there a guide around for the best way to adjust fine focus when using a zoom lens?

K.

I usually adjust for infinity focus at the long end of the zoom, on the assumption that there is more latitude at shorter focal lengths with greater depth of field.

Hahah

Here's what I do.

Focus on a well defined object at a reasonably far distance. Something like a tree branch/leaves at 20 or so metres with the sky behind it.

Use a tripod and centre focus spot on both live view and viewfinder modes.

Line up the shot using live view, then AF and shoot once to ensure you're happy with the object in focus. Take a reading of the focus scale now, maybe snap an image using your phone for reference. This is the 'correct' focus scale marking for your chosen object.

Now go into viewfinder mode, shift the lens away from correct focus and get the AF to work by pressing the button until confirmed. You can either snap a shot to compare with the previous on 100% image zoom (increases the shutter count) or compare the focus scale with what you had before. If you do this a few times you'll be able to get an idea of how far off your AF adjustment is likely to be.

Now adjust the fine focus value to one of the extremes and repeat. I do this because I ALWAYS forget which adjustment direction is needed to sort out front/back focus. One of the two extremes will bring you towards the correct focus, the other will be way off.

Keep repeating this process for different values of fine focus and you'll start to home in on the perfect adjustment value.

When you're really close, the focus scale might not be enough to differentiate. At this point, snap shots and look at the images at 100% zoom.

I usually aim to get correct focus at the first confirmation of the AF button.