[smcseth]

Hey everyone! I am looking for some input on an issue I have run into with my HD 16-85. I just purchased it last week and took it out over the weekend to get familiar with it. So much about this zoom is a pleasure, and I typically use primes. Solid feel, surprisingly good corners on the wide end, and quiet (not silent) focus.

But I quickly ran into an issue when focusing on more distant subjects. I was trying to auto-focus on a building about 75 yards away. This was not a low-light situation. I was using the following settings: Aperture priority, lens at 16mm, f8, auto ISO (100), evaluative metering, center point auto-focus, af-s, using the viewfinder, battery grip attached. When putting the focus point on the building and using the shutter button to auto-focus, I would get the central red indicator momentarily (as usual) but the green hexagon focus lock indicator would flash continuously. If I released the shutter button and tried again on the same building, I got the flashing hexagon again. If I tried focusing on a shrub 10 feet in front of me, perfect focus. Back to the building, flashing hexagon. If I refocused and recomposed enough, I could eventually get the shot. Some came back out of focus. As my day went along, I noticed it most often on subjects more than 100 feet away, but sometimes on closer things as well.

I changed settings, focal lengths (could happen across the range but more often on the wider third) turned the camera on/off, mounted/dismounted the lens, checked the contacts on the body & lens, tried it with the battery grip off, different auto-focus point modes (never tried live view), etc. It still happened. My fiance 20 feet away? Focused. The brick wall 30 yards behind her? Hit or miss. Again, when it locked focus it was very accurate. But about a third of my day involved a flashing focus lock indicator and an inability to trigger the shutter. It was frustrating. Never noticed this behavior with any of my other auto-focus lenses. Any help is greatly appreciated!

[RMabo]

It does seems like something is wrong with it. Send it back to where you purchased it, ask for service under warranty..

[MortenV]

I don't know if this will help you, but I own a Pentax DA 18-135 with exactly the same behavior as yours. I was tired of the problem and AF fine adjustment couldn't solve the problem.
I decided then to buy a DA 16-85. I´ve received it just to realize that it was very bad decentered making photos very blurry in the top.
I decided to use the 2 year warranty and contacted the nearest Pentax service center. I send them some photos and they replied that I should send them the lens to service.
A week ago I got the same lens back and now it was adjusted to perfection. Its like a knew lens. Totally sharp at all focal lengths and no decentering.
I've compared it to my very sharp Pentax F28 and I´m not able to distinguish them.
So the DA 16-85 can be very good, but it depends on the Pentax QC which differs very much from lens to lens.
I wish I could do the same with the DA 18-135, but I can't find the reciept.

[Adam]

In your case it's possible that some minor af adjustments will do the trick. Try dialing in -10, see if you're able to focus in distant subjects, and if so dial the adjustment back as appropriate.

Adam
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[lytrytyr]

(never tried live view),
Any help is greatly appreciated!

Try it with CDAF in live view.
If it works fine that way, then an adjustment on the (PD)AF
for viewfinder focusing may help.

If it doesn't work in live view,
the lens may be set up badly,
e.g. not reaching infinity when wide open,
or not far enough beyone infinity for the AF to work.

Worst case, the lens may be "parfocal" enough
that you can do your long-range focusing at a tele setting,
and then zoom in for your wide-angle shot.

[smcseth]

Thanks for the replies, everyone. I am going to try some of the suggestions here. Since the lens seems to be a solid copy optically, it would be nice to not have a reason to swap it. I'll post the results in a couple of days. Thanks again!

[bwDraco]

Sounds like a mechanical issue with the lens. The focusing group is so far off that the lens won't focus to infinity any more. I have a similar issue with my 18-135 due to the focusing group being loose inside the lens. Tilting the lens up would solve the problem.

—DragonLord

[smcseth]

Sounds like a mechanical issue with the lens. The focusing group is so far off that the lens won't focus to infinity any more. I have a similar issue with my 18-135 due to the focusing group being loose inside the lens. Tilting the lens up would solve the problem.

—DragonLord

I noticed this day before yesterday while shooting a cityscape! If I point the camera straight up, the focus locks. But outside of that "fixing" it, the flashing focus lock problem still happens, happens with focus adjustments, happens in live view. And this fix only works for infinity focus, not so well on intermediate subjects. I'll be exchanging the lens. No biggie.

[Mike Gezing]

smcseth,

Looks like I'm having the same problem that you are having with a HD DA 16-85mm that I bought last week. I'll be sending mine back for another copy, did you ever get a new lens and does it function better?

Mike G