Pentax 50-135 will not auto focus on some of my models


almierau

Link Posted 03/12/2014 - 03:42
For some reason my SMC Pentax DA -50-135 lens will no longer auto focus when used with my K10 or my newer K7. I was just about to take the lens to the dealer to send away and decided to haul out my two older *isD models, *isD S and *isD L. Focuses instantly without an issue.

My other Pentax lenses and Sigma lenses all work correctly with the K7 and K10. Is there a solution for this? And what would cause this. I never did use that lens on the K10 but decided just to see if it would work or not.

Hope someone has some ideas here as that lens is my primary lens for coach trips.

Jonathan-Mac

Link Posted 03/12/2014 - 08:36
It sounds like the in-built motor is not working. I think the older two bodies use the focusing motor of the camera (rather than the lens) as they can't use in-lens motors.

Check if all the electrical contacts on the lens and the cameras are clean. The AF motor contacts are the ones slightly inside the mount (not on the mount ring itself).

If that doesn't work, then you may have problems with the motor itself (you wouldn't be the first person to have this problem). Sometimes the AF motor can be jogged into functionality by moving the focusing ring manually a bit, but this is likely a temporary fix and the lens will need to be repaired for it to work well long-term.

Good luck.
Pentax hybrid user - Digital K3, film 645 and 35mm SLR and Pentax (&other) lenses adapted to Fuji X and Panasonic L digital
Fan of DA limited and old manual lenses

Daronl

Link Posted 03/12/2014 - 09:51
Had identical problem, Pentax couldn't get a new motor quickly so replaced the lens

almierau wrote:
For some reason my SMC Pentax DA -50-135 lens will no longer auto focus when used with my K10 or my newer K7. I was just about to take the lens to the dealer to send away and decided to haul out my two older *isD models, *isD S and *isD L. Focuses instantly without an issue.

My other Pentax lenses and Sigma lenses all work correctly with the K7 and K10. Is there a solution for this? And what would cause this. I never did use that lens on the K10 but decided just to see if it would work or not.

Hope someone has some ideas here as that lens is my primary lens for coach trips.


Daronl

almierau

Link Posted 03/12/2014 - 13:17
Found the solution. A Canon user in Scotland advised me to perhaps turn off the stabilization feature on both the K7 and K10. That was something I had not thought of. When I did that the lens focused properly. I then turned the stabilization back on and the lens still focuses. And this may have been caused by operator error (me) as sometimes when out in the field I will switch lenses without turning off the camera. Thanks for the responses.
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