[Paul the Sunman]

I am currently travelling in Eastern Europe with the K3iii, DA 16-85, and four screw drive lenses (DA 15, 40, 70 Limiteds and HD DA 55-300 non-PLM). The DA 16-85 is driving me crazy. It auto-focuses fine for a while, and the images are very sharp. However, after a while it almost refuses to AF, despite excellent light, contrast, and structure in the subject. It should have no trouble at all, and the other lenses certainly don't. I try focusing on a subject, but there is no focus beep, and it is visually not in focus. I slightly move the focus point 10 or 20 times trying to get a "hit", and sometimes I eventually do. But sometimes I just give up.

I mostly use AF-S spot focus, or 5-point focus.

It "seems", though I can't be sure, that it improves for a while if I turn off the camera, remove the lens, and remount it. This may not be right, just a couple of random occurrences.

When I get back to Aus in a few weeks I'll test it on my K5 and K3, but for the moment I have no alternate camera.

The lens got a slight knock a couple of weeks ago when I tripped on a hike, and the hood hit to ground not-very-violently. I am not sure if this is responsible.

Has anyone else had AF problems with this lens/camera combination? Any suggested tests or fixes? I will get it checked at CRK when I get back to Australia if I can't figure it out.

[jgnfld]

I am currently travelling in Eastern Europe with the K3iii, DA 16-85, and four screw drive lenses (DA 15, 40, 70 Limiteds and HD DA 55-300 non-PLM). The DA 16-85 is driving me crazy. It auto-focuses fine for a while, and the images are very sharp. However, after a while it almost refuses to AF, despite excellent light, contrast, and structure in the subject. It should have no trouble at all, and the other lenses certainly don't. I try focusing on a subject, but there is no focus beep, and it is visually not in focus. I slightly move the focus point 10 or 20 times trying to get a "hit", and sometimes I eventually do. But sometimes I just give up.

I mostly use AF-S spot focus, or 5-point focus.

It "seems", though I can't be sure, that it improves for a while if I turn off the camera, remove the lens, and remount it. This may not be right, just a couple of random occurrences.

When I get back to Aus in a few weeks I'll test it on my K5 and K3, but for the moment I have no alternate camera.

The lens got a slight knock a couple of weeks ago when I tripped on a hike, and the hood hit to ground not-very-violently. I am not sure if this is responsible.

Has anyone else had AF problems with this lens/camera combination? Any suggested tests or fixes? I will get it checked at CRK when I get back to Australia if I can't figure it out.

Dirt in the contacts??? Try an alcohol-dipped swab.

[hcc]

Sorry to hear your trouble.
Could any settings inadvertently been input (in the camera body) caused this? Is it worth to consider a camera body reset?
Hope that you can resolve it before being back to Oz...

[Not a Number]

The "knock" could have jarred some of the internal contacts out of alignment. If the problem happens more frequently within a range of focal length settings I would suspect this is the case.

[Terry C]

I have that lens, and often have the same trouble. Oddly, it is fine indoors in less than ideal light but outdoors often just hunts. If using it at the wide angle end, I find that I have to zoom it to max, focus then gradually bring it back in steps refocussing each time. It has the worst AF focus characteristics that I have ever encountered. Apparently this is quite a common problem with this lens.

[Pentax Syntax]

Mine suffered a fall like you described and would focus intermittently. Sent in for repair and came back like new. They replaced the DC motor etc and has worked fine since.

[timb64]

In over seven years of ownership I’ve never experienced the sort of problem you mention.As others said the knock it took is probably the cause.Best send it for assessment/repair upon your return.

[Madaboutpix]

Only last month returned a hopelessly decentered, erratically-focusing, and springless-aperture 16-85 to the eBay seller from whom I had bought it cosmetically as good as new and allegedly "professionally checked and fully functional". Use the other lenses you've brought, Paul, and bypass the 16-85 till the issues have been properly assessed (and hopefully solved), or you will end up with the bulk of your travel images ruined. (Yep, that's exactly what happened to me.)

A wish for the next generation of the prosumer standard zoom: Please, Ricoh, design it with PLM and electromagnetic aperture, make it come with AF algorithms that actually work, and ensure better consistency in the manufacture. The current optical design seems to make for a great lens, but it is held back by its mechanical and electronic implementation. So wanted to love the 16-85 as it is, but I shall either wait for the next iteration or might go for the DA*16-50 PLM instead if I should get a good deal.

[Jonathan Mac]

I have had occasional AF problems with my 16-85mm but nothing as bad as what you describe. Sometimes it tries to focus, fails completely, but gives a confirmation beep anyway. It doesn't happen often thankfully.

It could be just a question of cleaning the contacts though - poor electronic contact can cause AF failure in lenses with an in-built motor.

The Limited lenses you have with you will provide a good spread of focal lengths and excellent image quality if the zoom is unusable.

[FotoGekko]

You are describing the exact symptoms I have, on and off. You don't mention it specifically, but mine doesn't confirm focus (beep and green diamond). To add to (my) mysterie; apart from it happening irregularly, it does seem to happen more often with infinity focus. If after failing to focus at infinity and I aim at the ground for instance, it will operate allright. Mine was bought used 5 years ago, no dropping or so (while in my possession that is) and is mostly used on a Kp. Didn't have this trouble on my old K30, but haven't really compared since, my K30 is more or less glued to my 18-135 now.

Cheers, Gerard

NB Reading Terry C's message, it could of course be the light, since the ground is obviously less well lit.....I hardly use mine inside

[gerardbaron]

Pentax KP with DA * 16-50mm 2.8
Same behaviour
Clean contact
Reset camera
Etc…
The only way to make it work is zoom out and in.
I think everything you describe happen to this lens.
I will try the glass on a K1 II and will let you know.

[Paul the Sunman]

I have that lens, and often have the same trouble. Oddly, it is fine indoors in less than ideal light but outdoors often just hunts. If using it at the wide angle end, I find that I have to zoom it to max, focus then gradually bring it back in steps refocussing each time. It has the worst AF focus characteristics that I have ever encountered. Apparently this is quite a common problem with this lens.

Mine is worse at the long end.