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08-03-2020, 11:06 AM   #1
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Is it normal for needing 50-135 lens repaired twice?

So I have a few questions.... I bought the SMC-DA 50-135 lens back in 2011. In 2014 it would not focus at all in AF so I sent it to Precision for repair. Worked fine until this summer and now it won't Auto Focus again. Sent it back to Precision and to repair this time they quoted me at $526. Looked on Amazon and new they are selling for $700. My first thought is just to buy a new one However, what are the chances the new one will have to be repaired too? Has Pentax done anything different with more recently manufactured lenses to keep them from having this problem? Am I better off with a new lens and chance it having issues at some point? Or better off with a lens that has been repaired (twice) ?

08-03-2020, 11:09 AM - 1 Like   #2
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QuoteOriginally posted by BethC Quote
So I have a few questions.... I bought the SMC-DA 50-135 lens back in 2011. In 2014 it would not focus at all in AF so I sent it to Precision for repair. Worked fine until this summer and now it won't Auto Focus again. Sent it back to Precision and to repair this time they quoted me at $526. Looked on Amazon and new they are selling for $700. My first thought is just to buy a new one However, what are the chances the new one will have to be repaired too? Has Pentax done anything different with more recently manufactured lenses to keep them from having this problem? Am I better off with a new lens and chance it having issues at some point? Or better off with a lens that has been repaired (twice) ?
Would you be interested in conversion to screw drive as an option?


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08-03-2020, 11:12 AM   #3
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QuoteOriginally posted by stevebrot Quote
Would you be interested in conversion to screw drive as an option?


Steve
To be honest with you I don't know what that means. Can you explain to me?

---------- Post added 08-03-2020 at 02:13 PM ----------

I was actually going to buy myself a K-1 Mark 2, but am bummed if I have to put all the money into either a repair or a new lens I will have to put off buying a new body
08-03-2020, 11:29 AM - 1 Like   #4
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QuoteOriginally posted by BethC Quote
So I have a few questions.... I bought the SMC-DA 50-135 lens back in 2011. In 2014 it would not focus at all in AF so I sent it to Precision for repair. Worked fine until this summer and now it won't Auto Focus again. Sent it back to Precision and to repair this time they quoted me at $526. Looked on Amazon and new they are selling for $700. My first thought is just to buy a new one However, what are the chances the new one will have to be repaired too? Has Pentax done anything different with more recently manufactured lenses to keep them from having this problem? Am I better off with a new lens and chance it having issues at some point? Or better off with a lens that has been repaired (twice) ?
Hi Beth, I bought a used 50-135 and the owner sent an invoice showing the focus motor had been replaced. Without getting specific on dates, within the year, the motor failed again (slowly then totalled) and sent it in and had the motor replaced. Within a year, the new motor failed again (that would have been motor 3) and did the same debate you're going through. Decided to convert it to screw drive and have never looked back. A little noisy but it's quick and accurate nwo. Discussing the motor issue withe repair shop it was more or less a discussion they can only repair with the parts available and if those haven't been improved at the manufacturer the problem will continue. They actually indicated it wasn't the motor proper but something to do with th electronic controls that needed to be constantly used to keep functional.

08-03-2020, 11:33 AM - 4 Likes   #5
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QuoteOriginally posted by BethC Quote
To be honest with you I don't know what that means. Can you explain to me?

---------- Post added 08-03-2020 at 02:13 PM ----------

I was actually going to buy myself a K-1 Mark 2, but am bummed if I have to put all the money into either a repair or a new lens I will have to put off buying a new body
The K1 is full-frame. The 50-135 is APS-C format, so while it will "work", you won't be getting all the camera has to offer. If you are upgrading to the K1, you are probably going to be wanting different lenses all around.

As to the other question, there are two focusing systems in use: in-lens motors (the SDM in the 50-135 is an in-lens motor), and the in-body motor (also called screw drive commonly). The oldest Pentax autofocus cameras only had screw-drive, and they do not support in-lens motors. Because of this a few SDM lenses, including the 50-135 are capable of operating with either method. However, if the lens is attached to a modern body, it only wants to focus in SDM mode, not in screw-drive mode. There is a 'hack' of sorts where one changes the firmware on the lens so that it always thinks it's on an older body so it always uses the screw-drive. The downside is that it is a little noisier. The upside is it is nearly 100% reliable and should last more or less forever. If you have any older or more affordable lenses that make more noise when focusing, those are screw drive. That's pretty much what a converted 50-135 will sound like. It's not terrible, and it's a low-cost solution to your problem.

One of the users on the forum, Uncle Vanya, will do the conversion for you for a modest fee, and return your lens to you functioning with screw drive. Send him an IM and I'm sure you can work it out with him. You can find a posting from him in the marketplace here on the forum:
https://www.pentaxforums.com/forums/24-photographic-equipment-sale/311609-sa...nversions.html
08-03-2020, 11:35 AM   #6
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QuoteOriginally posted by AlwaysAl Quote
Hi Beth, I bought a used 50-135 and the owner sent an invoice showing the focus motor had been replaced. Without getting specific on dates, within the year, the motor failed again (slowly then totalled) and sent it in and had the motor replaced. Within a year, the new motor failed again (that would have been motor 3) and did the same debate you're going through. Decided to convert it to screw drive and have never looked back. A little noisy but it's quick and accurate nwo. Discussing the motor issue withe repair shop it was more or less a discussion they can only repair with the parts available and if those haven't been improved at the manufacturer the problem will continue. They actually indicated it wasn't the motor proper but something to do with th electronic controls that needed to be constantly used to keep functional.
Thanks for your input! I have been looking into the screw drive option since Steve posted about it. And I am definitely interested, however I"m concerned with the noise. I don't shoot a lot of weddings but occasionally will and I"m afraid it will be too loud to use during a wedding ceremony. Any thoughts on that?

---------- Post added 08-03-2020 at 02:38 PM ----------

QuoteOriginally posted by Kozlok Quote
The K1 is full-frame. The 50-135 is APS-C format, so while it will "work", you won't be getting all the camera has to offer. If you are upgrading to the K1, you are probably going to be wanting different lenses all around.

As to the other question, there are two focusing systems in use: in-lens motors (the SDM in the 50-135 is an in-lens motor), and the in-body motor (also called screw drive commonly). The oldest Pentax autofocus cameras only had screw-drive, and they do not support in-lens motors. Because of this a few SDM lenses, including the 50-135 are capable of operating with either method. However, if the lens is attached to a modern body, it only wants to focus in SDM mode, not in screw-drive mode. There is a 'hack' of sorts where one changes the firmware on the lens so that it always thinks it's on an older body so it always uses the screw-drive. The downside is that it is a little noisier. The upside is it is nearly 100% reliable and should last more or less forever. If you have any older or more affordable lenses that make more noise when focusing, those are screw drive. That's pretty much what a converted 50-135 will sound like. It's not terrible, and it's a low-cost solution to your problem.

One of the users on the forum, Uncle Vanya, will do the conversion for you for a modest fee, and return your lens to you functioning with screw drive. Send him an IM and I'm sure you can work it out with him.
Thank you for the explanation! I'm very interested in having it converted to screw drive, however am concerned about the noise. As I posted in response above, I occasionally shoot weddings, not often, but every once in a while. Is the lens to loud to use during a wedding ceremony?
08-03-2020, 11:39 AM - 1 Like   #7
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QuoteOriginally posted by BethC Quote
To be honest with you I don't know what that means. Can you explain to me?
- the 50-135 is an SDM lens meaning that it has a motor in the lens that moves the elements into focus. It also has the ability to use the older in camera motor which is far more reliable. However it will not that automatically but it can be done. The result is that the faulty in lens motor is bypassed. The downside is that the AF is somewhat nosier.
- A number of SDM lenses (16-50, 50-135 and 60-250) have had a poor reputation for failure. Supposedly newer lenses have a different motor that is more reliable.
QuoteOriginally posted by BethC Quote
I was actually going to buy myself a K-1 Mark 2,
- the 50-135 is an APS-C lens and is not capable of covering the image circle of the K-1. So if you are planning to buy a K-1 you will need a new lens for that camera. If you are keeping your current body then replacing or repairing your 50-135 for that body is a good idea. But if you are moving to FF with the K-1 then consider selling the 50-135 "as is" and get a new lens for the K-1
08-03-2020, 12:28 PM   #8
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QuoteOriginally posted by jatrax Quote
- the 50-135 is an SDM lens meaning that it has a motor in the lens that moves the elements into focus. It also has the ability to use the older in camera motor which is far more reliable. However it will not that automatically but it can be done. The result is that the faulty in lens motor is bypassed. The downside is that the AF is somewhat nosier.
- A number of SDM lenses (16-50, 50-135 and 60-250) have had a poor reputation for failure. Supposedly newer lenses have a different motor that is more reliable.

- the 50-135 is an APS-C lens and is not capable of covering the image circle of the K-1. So if you are planning to buy a K-1 you will need a new lens for that camera. If you are keeping your current body then replacing or repairing your 50-135 for that body is a good idea. But if you are moving to FF with the K-1 then consider selling the 50-135 "as is" and get a new lens for the K-1
Thanks for the info. After reading responses and looking into the post that was linked above about sending out to have it made screw drive, I"m going to go ahead and do that. For what he charges if it's too loud for the very rare times I shoot a wedding, I'll just rent a lens for the weekend.

08-03-2020, 02:14 PM - 1 Like   #9
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QuoteOriginally posted by BethC Quote
Thanks for your input! I have been looking into the screw drive option since Steve posted about it. And I am definitely interested, however I"m concerned with the noise. I don't shoot a lot of weddings but occasionally will and I"m afraid it will be too loud to use during a wedding ceremony. Any thoughts on that?

---------- Post added 08-03-2020 at 02:38 PM ----------



Thank you for the explanation! I'm very interested in having it converted to screw drive, however am concerned about the noise. As I posted in response above, I occasionally shoot weddings, not often, but every once in a while. Is the lens to loud to use during a wedding ceremony?
Hi Beth, The "noise" isn't excessive, just standard for a the older style of lense. In a wedding, doubt anyone will notice the noise or find it out of place. BTW, someone on this forum posted a procedure to convert the lense to screw drive yourself. It was very simple to follow and worked like a charm.

How To: Convert SDM to ScrewDrive + Video - PentaxForums.com
08-03-2020, 04:03 PM   #10
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QuoteOriginally posted by AlwaysAl Quote
Hi Beth, The "noise" isn't excessive, just standard for a the older style of lense. In a wedding, doubt anyone will notice the noise or find it out of place. BTW, someone on this forum posted a procedure to convert the lense to screw drive yourself. It was very simple to follow and worked like a charm.

How To: Convert SDM to ScrewDrive + Video - PentaxForums.com
Thanks for the link! I watched a youtube video earlier with instructions. However, my husband thinks for what little is charged to do it I should just send it away. I'm torn. I have an event coming up soonish that I'd love to have it for so I'm not sure what I will do.
08-03-2020, 06:30 PM   #11
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QuoteOriginally posted by jatrax Quote
- A number of SDM lenses (16-50, 50-135 and 60-250) have had a poor reputation for failure. Supposedly newer lenses have a different motor that is more reliable.
Are these, plus the DA55, the full set of SDM lenses?
08-03-2020, 06:44 PM   #12
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QuoteOriginally posted by leekil Quote
Are these, plus the DA55, the full set of SDM lenses?
Not by any means. The DA*200 and DA*300 have SDM as well. Of the DA* lenses, the 16-50 and 50-135 have by far the worst reputation for failure, with the 60-250 a distant third. It least that's my impression.

I don't own it, but I gather the DA17-70 has SDM too. More reliable though.

Other lenses with nominal SDM AF, like the Tamron-designed DA18-270, DFA15-30 and DFA24-70, should not be tarred with the same brush.
08-03-2020, 10:06 PM   #13
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QuoteOriginally posted by Sandy Hancock Quote
Not by any means. The DA*200 and DA*300 have SDM as well. Of the DA* lenses, the 16-50 and 50-135 have by far the worst reputation for failure, with the 60-250 a distant third. It least that's my impression.

I don't own it, but I gather the DA17-70 has SDM too. More reliable though.

Other lenses with nominal SDM AF, like the Tamron-designed DA18-270, DFA15-30 and DFA24-70, should not be tarred with the same brush.

My own impression is slightly different. I would rank the failure rate of the 16-50 and 50-135 similar to Sandy. But the 300 would be next on my list followed by the 60-250 then the 200.

I would also put the failure rate of the 17-70 pretty high - at least that's what I was told years ago. The one refurbished 17-70 I have personal experience with is still going strong 4 years later (owned by a relative. )
08-04-2020, 01:51 AM   #14
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QuoteOriginally posted by UncleVanya Quote
My own impression is slightly different.
I would happy defer to your far greater experience
08-04-2020, 02:20 AM   #15
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Auto focus repairs to SDM lenses are well known to be short-lived. I hear there's a version 2 of the 16-55mm coming out some time soon but the whole DA* range of lenses is well overdue a re-design, more than anything to fix the AF problems.

While some have had no problems with these lenses, many people have. I just avoid them, which is a shame because there are some I'd really like to have.
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