[Canada_Rockies]

I returned my 50-135 to Pentax when I sent in my k10d for repairs, and because it had "Moody Mood" syndrome and the warranty was running out. It was returned to me, and appears so far to be working much better. The notation was "Cleaned and adjusted contacts". I've been doing the cleaning bit quite often, but had no idea the contacts could be adjusted.

[philbaum]

I returned my 50-135 to Pentax when I sent in my k10d for repairs, and because it had "Moody Mood" syndrome and the warranty was running out. It was returned to me, and appears so far to be working much better. The notation was "Cleaned and adjusted contacts". I've been doing the cleaning bit quite often, but had no idea the contacts could be adjusted.

I just wish that Pentax or some technician would come out and say what the dang problem is. There was some statement over on DPR that there was a plastic bracket that wasn't installed correctly. I find that hard to believe when we see the statistics in this poll that show a number of failures on all lenses but 200 and 300. All these lenses couldn't have been manufactured at the same time. Very irritating that they wouldnt' come out and say what the problem is. Of course when they do that, in some countries i suppose, they would be legally held accountable for repairs after admitting in public some weakness.

But to get back to your repair, the SDM motor in the lens must be drawing more current than any other lens circuit, i would think. Could it be that the SDM motor circuit is more sensitive to contact performance than the rest of the lens circuits?

Where's my head :-), the SDM uses those two little zoom contacts on the inside of the mount ring to power the motor. I can't believe that those are the sole problem area, as there have been too many posts reporting that internal repairs to the lens had to be accomplished and only certain repair centers had the technology. Also, any number of people have reported cleaning the contacts with no improvement afterward.

[Canada_Rockies]

I just wish that Pentax or some technician would come out and say what the dang problem is. There was some statement over on DPR that there was a plastic bracket that wasn't installed correctly. I find that hard to believe when we see the statistics in this poll that show a number of failures on all lenses but 200 and 300. All these lenses couldn't have been manufactured at the same time. Very irritating that they wouldnt' come out and say what the problem is. Of course when they do that, in some countries i suppose, they would be legally held accountable for repairs after admitting in public some weakness.

But to get back to your repair, the SDM motor in the lens must be drawing more current than any other lens circuit, i would think. Could it be that the SDM motor circuit is more sensitive to contact performance than the rest of the lens circuits?

Where's my head :-), the SDM uses those two little zoom contacts on the inside of the mount ring to power the motor. I can't believe that those are the sole problem area, as there have been too many posts reporting that internal repairs to the lens had to be accomplished and only certain repair centers had the technology. Also, any number of people have reported cleaning the contacts with no improvement afterward.

I have not had the lens back long enough to find out whether their fix was permanent. I am sure there are others who have had complete failures of the SDM, and was not trying in any way to dismiss those problems. I was attempting to point out that there is possibly another cause for the apparent failures. The main reason I sent it in was to get the lens registered as having been returned before the warranty ran out. If it turns out that the fix was not a fix, I should be able to claim inappropriate warranty work and get a correct repair done later without taking out a mortgage.

[Bart]

...
This should not include:

• front/back focus issues
• hunting
• failure to lock focus
• other lens issues (e.g. centering defect)

I believe it is not correct to exclude this issue from SDM related failures.
I had this exact problem with my 16-50 and after Pentax tried to repare this a number of times, they replaced it with a new copy.
They said this was due to an SDM problem.

[Ash]

Bart, under what conditions did your old 16-50 not lock focus?

[Russell-Evans]

Bart, under what conditions did your old 16-50 not lock focus?

Not to answer for Bart, but the other three posts I've seen describing this issue: the focus won't lock in any condition. The motor only stops at the end of the focus travel.

Thank you
Russell

[Ash]

Then this is quite a different issue to the intermittent failure to lock focus at infinity focus distance.

[Russell-Evans]

Then this is quite a different issue to the intermittent failure to lock focus at infinity focus distance.

Where did you get this issue? Is this something else besides the lenses refusing to lock focus?

I looked through Bart's posts and I think this is the one he was talking about:

It started yesterday but that was a very dark and grey day so I let it go by.
Today however was a very sunny day and it happened again. Strangely, at 16mm there didn't seem to be a problem. Any longer length refused to lock.
I removed the lens and attached it again and that seemed to help - for a while.

Edit: I see you are talking about the issue with the returned "fixed" lens after it had been in for service as noted in this post.

So, I send both K10D and the lens in for service after I had a talk with a technician at Pentax Belgium. As they do not deal with the general public, I had to send the items through the local shop where I bought the K10D. This was end of March. Half May I was told the camera was now in Pentax Germany waiting for a part from Japan.
Finally, I got everything back last Saturday. That's about 2,5 months! The note stated the AF mechanism was repaired, tuned and tested.
However... The first test I did with the 16-50 revealed the AF still wouldn't lock with the longer focus lengths on long distances! It's as if the mechanism can't reach infinity.

Thank you
Russell

[Ash]

Russell, this is what I've experienced with my 16-50, and Peter Z has confirmed the phenomenon with his copy.

It happens at times when trying to focus at infinity (let's say for a landscape shot) even if in high contrast conditions, AF hunts a little around infinity and then gives up with the blinking hexagon.

The AF mechanism itself works fine otherwise - close focus snaps on quickly and then it may lock at infinity thereafter, but trying again at an infinity distance subject may lead to another failure to lock focus.

[stevebrot]

Russell, this is what I've experienced with my 16-50, and Peter Z has confirmed the phenomenon with his copy.

It happens at times when trying to focus at infinity (let's say for a landscape shot) even if in high contrast conditions, AF hunts a little around infinity and then gives up with the blinking hexagon.

The AF mechanism itself works fine otherwise - close focus snaps on quickly and then it may lock at infinity thereafter, but trying again at an infinity distance subject may lead to another failure to lock focus.

This sounds a lot like what I witnessed at a scenic overlook a little over a year ago. I was having no problems (manual focus lens), but the guy with a Canon 40D next to me could not attain focus on the subject about 300 yards away. The lens would hunt for a bit and then just give up. He finally just switched to manual and got his shot.

Steve

[Canada_Rockies]

This sounds a lot like what I witnessed at a scenic overlook a little over a year ago. I was having no problems (manual focus lens), but the guy with a Canon 40D next to me could not attain focus on the subject about 300 yards away. The lens would hunt for a bit and then just give up. He finally just switched to manual and got his shot.

Steve

I wonder if it is due to the difficulty of focusing ultra wide lenses in general? I have not had too much difficulty with mine, but occasionally, I have to point it at something with some contrast, particularly at the wider angles, 16 - 18 mm. I figure the AF has the same problem as we all have trying to focus an ultra wide lens. It is difficult.

[Rondec]

It is definitely harder to auto focus at 16mm than at 50mm. The focus points are too big to pick up contrast. This is usually the case at infinity focus and not with things that are closer. I think it is more an issue with the auto focus system than with the lens.

[builttospill]

When my 17-70 lens couldn't lock focus it wasn't just doing it occasionally, it was every time. So either it was in a really bad mood the entire week or something else...

The lens would hunt across the entire focus range, not just at infinity, then give up and give me the blinking hexagon. This occured not just at wide-angle focal lengths, but from 17 to 70mm's.

[MJB DIGITAL]

My problem has been with bodies losing sdm control

[netuser]

My problem has been with bodies losing sdm control

Bodies ? Care to explain ???