Non reliable DC motor on DA HD 16-85

sbc · 12-26-2016, 03:22 AM

Just bought a DA 16-85 from B&H. I too am starting to have problem with the focusing. For my case, it seems like there is a lot of friction in the AF mechanism and the DC motor does have enough torque to move it. If the subject is very out of focus, the AF will work. But if it is just so slightly out of focus, the AF will just stall and refuse to do anything. All the viewfinder display will blink. Also LV AF will not work. I am not too sure if that is the lens' fault or my K-5IIs'.

Timd · 12-26-2016, 11:40 AM

Originally posted by mario.abcunha

Hey guys! Anyone had a problem with the DC motor on the 16-85 HD lens? It doesn't lock focus, I have to press the af button like 5 times and it gets closer and closer and eventually focus... I have tried both on a K3 and K3II same thing happened. However sometimes it works, this is using the viewfinder. When using live view it never locks. Already clean the contacts and I don't have the problem with any other lens.

Anyone experienced the same issue? Or any ideas of what could it be?

Thanks

This sounds very similar to my daughters 18-50 DC RE lens. It's in for repair....

Fussy Pentax User · 12-19-2020, 05:01 AM

I have had exactly the same problem as Mario. Suddenly, about a year ago, I found I needed to press the shutter button around 5 times to get it to finally achieve autofocus, but this was at the 85mm end. It got a little closer to correct focus each time. At 16mm it seems to work normally most if not all the time. I'll try cleaning the contacts....

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12-26-2016, 03:22 AM	#16
sbc Pentaxian Join Date: Mar 2008 Photos: Albums Posts: 357	Just bought a DA 16-85 from B&H. I too am starting to have problem with the focusing. For my case, it seems like there is a lot of friction in the AF mechanism and the DC motor does have enough torque to move it. If the subject is very out of focus, the AF will work. But if it is just so slightly out of focus, the AF will just stall and refuse to do anything. All the viewfinder display will blink. Also LV AF will not work. I am not too sure if that is the lens' fault or my K-5IIs'.

12-26-2016, 11:40 AM	#17
Timd Senior Member Join Date: Dec 2008 Location: Cape Town, SA Posts: 262	Originally posted by mario.abcunha Hey guys! Anyone had a problem with the DC motor on the 16-85 HD lens? It doesn't lock focus, I have to press the af button like 5 times and it gets closer and closer and eventually focus... I have tried both on a K3 and K3II same thing happened. However sometimes it works, this is using the viewfinder. When using live view it never locks. Already clean the contacts and I don't have the problem with any other lens. Anyone experienced the same issue? Or any ideas of what could it be? Thanks This sounds very similar to my daughters 18-50 DC RE lens. It's in for repair....

12-19-2020, 05:01 AM	#18
Fussy Pentax User Senior Member Join Date: Apr 2014 Posts: 363	I have had exactly the same problem as Mario. Suddenly, about a year ago, I found I needed to press the shutter button around 5 times to get it to finally achieve autofocus, but this was at the 85mm end. It got a little closer to correct focus each time. At 16mm it seems to work normally most if not all the time. I'll try cleaning the contacts....