[akptc]

Just got this used DA50-135 with SDM drive on. The lens focuses nicely but there is a squeak. It's not super loud but noticeable. This is the first time I've ever heard such a high pitched squeak on an SDM lens.

LINK TO THE SOUND FILE OF THE SQUEAK

I am thinking I will use the lens until the SDM fails then convert it to screw drive..

But, based on the squeak, can you tell how long before it fails? (I know it's probably a nearly impossible question to answer).

Thank you in advance for your advice and opinions.

Andy

[bertwert]

But, based on the squeak, can you tell how long before it fails? (I know it's probably a nearly impossible question to answer).

How long is a piece of string?

[hyyz]

In my experience with SDM lenses, the AF behavior of each one is different. One is completely silent and AF quickly. Another one is completely silent but AF slowly. A third one is squeaking like yours and AF quickly. A fourth one is squeaking like yours but often cannot lock focus. All in all, I feel SDM is a bad design from Pentax in that they can't even make the behavior consistent. Time for them to update their SDM lenses.

Sorry I don't have an answer to question.

[DrawsACircle]

Sounds like my da*300 with a dying SDM motor, I have to switch to liveview to wake it up.

[sergysergy]

I have a 55 sdm that always made the sound but never gave me problems. Good thing about your lens is that you can convert it.

[Mike.P®]

My 50-135mm has made that noise for years.

[mikesbike]

I've had mine for over 10 years and fortunately it works fine without a sound. If the AF works very well, you can either use it as is, since you must have acquired it at a very good price, or if the sound annoys you compared tot the noise of a screw-driven lens, just have it converted. I have heard this also improves AF speed.

---------- Post added 01-25-20 at 01:48 PM ----------

In my experience with SDM lenses, the AF behavior of each one is different. One is completely silent and AF quickly. Another one is completely silent but AF slowly. A third one is squeaking like yours and AF quickly. A fourth one is squeaking like yours but often cannot lock focus. All in all, I feel SDM is a bad design from Pentax in that they can't even make the behavior consistent. Time for them to update their SDM lenses.

Sorry I don't have an answer to question.

From what I've read, Pentax already has taken this step. Supposedly, the newer production has an improved SDM mechanism, and other lenses designed in more recent years, have switched to DC motors, or PLM, or if "SDM" are actually rebadged models made by other manufacturers with an entirely different AF motor.

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Last edited by mikesbike; 01-25-2020 at 01:49 PM.

[akptc]

Thanks Everyone! I appreciate the quick feedback. Definitely keeping the lens and the sound is not a bother, just a curiousity.

[DWS1]

From what I've read, Pentax already has taken this step. Supposedly, the newer production has an improved SDM mechanism, and other lenses designed in more recent years, have switched to DC motors, or PLM, or if "SDM" are actually rebadged models made by other manufacturers with an entirely different AF motor.

I tend to agree with this assessment as well, which raises another question. Why have we only seen 1 lens released with the PLM motor and not much talk about its future use? I thought the KAF4 mount was implemented to allow for the use of the PLM focusing capabilities. It seems like they have just about abandoned the PLM technology. Personally, I think it works very well.

[Paul the Sunman]

I tend to agree with this assessment as well, which raises another question. Why have we only seen 1 lens released with the PLM motor and not much talk about its future use? I thought the KAF4 mount was implemented to allow for the use of the PLM focusing capabilities. It seems like they have just about abandoned the PLM technology. Personally, I think it works very well.

I think I heard that PLM is not suitable for heavier lenses like the 70-200 or 150-450.

[blackcloudbrew]

My 50-135mm has made that noise for years.

Yep, mine too.

[clickclick]

I think I heard that PLM is not suitable for heavier lenses like the 70-200 or 150-450.

Exactly. It isn't suited for big heavy optical groups, but is perfect for something like the 55-300 PLM.

[jddwoods]

My DA*200 (10 years old, pre 2012) and DA*300 (1 year old) both make a slight squeak at the moment when they lock focus. They both did it even when new and have not gotten worse over the years so I assume it is normal. I was concerned when I noticed it in the DA*200 but when I added a new DA* 300 and noticed the SDM sounded the same in both lenses I concluded it was not a problem issue. Both are working fine.

[DWS1]

I think I heard that PLM is not suitable for heavier lenses like the 70-200 or 150-450.

Exactly. It isn't suited for big heavy optical groups, but is perfect for something like the 55-300 PLM.

Thank you, I did not know that. Now I understand.

[c.a.m]

The lens focuses nicely but there is a squeak.

I don't know whether there is a correlation between the 'squeak' and an imminent SDM failure. However, my DA* 50-135 was repaired four times in 2013, including the SDM motor being replaced twice. Prior to the fourth failure and repair, the lens was squeaking noticeably, similar to your audio recording.

Ultimately, the lens failed again in 2014 and I converted it to screwdrive. No more squeaking and the lens works well, but of course the lens focus action is louder than the SDM drive.


- Craig