Quality/Reliability Issues w/ DFA* 50 F1.4 & DA*50-135

**Buckeyemikie** · 08-07-2020, 09:04 AM

Asking for suggestions on how to deal with quality issues on two of my lenses. 1) the green stripe ring on my DFA* 50 has fallen off. Luckily i found on the floor under my work table. Its 21 months since I bought it. It appears there was insufficient adhesive applied during assembly. If I can get Precision to answer their phone, I'll see what they say re repair cost. In the mean time, what do you think about just using super glue sparingly to reattach it myself? Would just leaving it off compromise AW protection?

2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead.

Would appreciate any thoughts/suggestions.

**sergysergy** · 08-07-2020, 09:13 AM - **1 Like**

Originally posted by Buckeyemikie

2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead.

Would appreciate any thoughts/suggestions.

I would convert it to screwdrive

**Buckeyemikie** · 08-07-2020, 09:19 AM

What would that cost?

**sergysergy** · 08-07-2020, 09:40 AM

You can do it for free with the right camera!

How to deactivate SDM and allow for screw drive autofocus with DA* 16-50mm f/2.8 - PentaxForums.com

**mikesbike** · 08-07-2020, 11:25 AM

If you don't have a capable camera to implement screw-driven operation, I'd suggest contacting UncleVanya.

Imp · 08-07-2020, 12:50 PM

Originally posted by mikesbike

If you don't have a capable camera to implement screw-driven operation, I'd suggest contacting UncleVanya.

I got mine done by UncleVanya, would recommend : )

stevebrot · 08-07-2020, 01:44 PM - **1 Like**

Originally posted by Buckeyemikie

what do you think about just using super glue sparingly to reattach it myself?

Conventional wisdom is to not let cyanoacrylate (super glue) anywhere near optics that might have non-glass elements. The vapors will craze most plastics.

Steve

**Buckeyemikie** · 08-07-2020, 06:35 PM

Thx to all for your comments...I’ll consider the info carefully.

**UncleVanya** · 08-07-2020, 07:19 PM - **2 Likes**

If you decide you like me to convert it, send me a pm. If you decide you want to convert it, after reading some of the threads on the subject feel free to post about your issues if you get stuck.

As for the green ring, I suggest a milder type of glue... Perhaps contact cement. Look at any of the threads on loose rubber lens rings. Here's an example thread:

Easy question: which glue for rubber focus ring?

**pentaxus** · 08-07-2020, 10:00 PM

I vote with UncleVanya, use contact cement.

Not a Number · 08-08-2020, 04:57 AM

I would not use superglue. A more friendly contact cement like Pliobond would probably be better. Pliobond is often used to glue back the rubber parts on camera bodies and lens barrels.

**mikesbike** · 08-08-2020, 03:43 PM

I cannot comment by first-hand experience, since the SDM of my own copy of the DA* 50-135mm I bought new some 10 years ago has worked just fine despite often sitting for months or even years between uses (hope this continues!), I've read comments of those who've converted theirs to screw-driven saying AF speed is improved. Others, however, say not. I do know the AF of my screw-driven lenses has improved, being faster and more sure on my KP- another benefit from getting this exceptional body. Perhaps those lenses having their own motor systems are not as camera-dependent for their AF, and thus no difference can be gained from camera advancements with these lenses- that is unclear to me. But without question, it is possible to upgrade AF performance of a screw-driven lens via an upgrade in camera design. That and reliability can be an advantage.

**monochrome** · 08-08-2020, 03:52 PM - **1 Like**

Originally posted by Buckeyemikie

Asking for suggestions on how to deal with quality issues on two of my lenses. 1) the green stripe ring on my DFA* 50 has fallen off. Luckily i found on the floor under my work table. Its 21 months since I bought it. It appears there was insufficient adhesive applied during assembly. If I can get Precision to answer their phone, I'll see what they say re repair cost. In the mean time, what do you think about just using super glue sparingly to reattach it myself? Would just leaving it off compromise AW protection?

Don’t use superglue. The fumes could fog the lens elements. Use double stick scotch tape cut to fit.

Originally posted by Buckeyemikie

2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead.

Would appreciate any thoughts/suggestions.

Convert it to screwdrive. It focuses faster than the SDM and unless you are in a silent cathedral the noise is undetectable.

**Buckeyemikie** · 08-08-2020, 05:50 PM

Great input-thx again.As for the green ring, I thought I'd show you what I'm dealing with, so attached are macro shots showing the glue residue on the lens body and the green ring. Glue seems to be the way to go & I WON'T use superglue. The ring itself is intricately machined to match as close as possible the lens body-pretty amazing. The last two shots shows the flash hack I used to make the macros. Works really well with nature subjects, too.

I'm still undecided on how to go with the 50-135. What does it cost to convert it to screw drive?.

**Buckeyemikie** · 08-08-2020, 05:51 PM

Forgot to attach the macros.

08-07-2020, 09:04 AM	#1
Buckeyemikie Site Supporter Join Date: Feb 2014 Photos: Gallery Posts: 503	*Quality/Reliability Issues w/ DFA 50 F1.4 & DA50-135* Asking for suggestions on how to deal with quality issues on two of my lenses. 1) the green stripe ring on my DFA* 50 has fallen off. Luckily i found on the floor under my work table. Its 21 months since I bought it. It appears there was insufficient adhesive applied during assembly. If I can get Precision to answer their phone, I'll see what they say re repair cost. In the mean time, what do you think about just using super glue sparingly to reattach it myself? Would just leaving it off compromise AW protection? 2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead. Would appreciate any thoughts/suggestions.

08-08-2020, 03:43 PM	#12
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	I cannot comment by first-hand experience, since the SDM of my own copy of the DA* 50-135mm I bought new some 10 years ago has worked just fine despite often sitting for months or even years between uses (hope this continues!), I've read comments of those who've converted theirs to screw-driven saying AF speed is improved. Others, however, say not. I do know the AF of my screw-driven lenses has improved, being faster and more sure on my KP- another benefit from getting this exceptional body. Perhaps those lenses having their own motor systems are not as camera-dependent for their AF, and thus no difference can be gained from camera advancements with these lenses- that is unclear to me. But without question, it is possible to upgrade AF performance of a screw-driven lens via an upgrade in camera design. That and reliability can be an advantage. Last edited by mikesbike; 08-08-2020 at 03:49 PM.

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08-07-2020, 09:13 AM - 1 Like	#2
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,170	Originally posted by Buckeyemikie 2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead. Would appreciate any thoughts/suggestions. I would convert it to screwdrive

08-07-2020, 09:19 AM	#3
Buckeyemikie Site Supporter Join Date: Feb 2014 Photos: Gallery Posts: 503 Original Poster	What would that cost?

08-07-2020, 09:40 AM	#4
sergysergy Site Supporter Join Date: Jan 2011 Photos: Gallery Posts: 5,170	You can do it for free with the right camera! How to deactivate SDM and allow for screw drive autofocus with DA* 16-50mm f/2.8 - PentaxForums.com

08-07-2020, 11:25 AM	#5
mikesbike Site Supporter Join Date: Dec 2016 Location: Southeastern Michigan Posts: 4,549	If you don't have a capable camera to implement screw-driven operation, I'd suggest contacting UncleVanya.

08-07-2020, 12:50 PM	#6
Imp Pentaxian Join Date: Nov 2014 Location: Washington, DC Photos: Gallery \| Albums Posts: 1,749	Originally posted by mikesbike If you don't have a capable camera to implement screw-driven operation, I'd suggest contacting UncleVanya. I got mine done by UncleVanya, would recommend : )

08-07-2020, 01:44 PM - 1 Like	#7
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Originally posted by Buckeyemikie what do you think about just using super glue sparingly to reattach it myself? Conventional wisdom is to not let cyanoacrylate (super glue) anywhere near optics that might have non-glass elements. The vapors will craze most plastics. Steve

08-07-2020, 06:35 PM	#8
Buckeyemikie Site Supporter Join Date: Feb 2014 Photos: Gallery Posts: 503 Original Poster	Thx to all for your comments...I’ll consider the info carefully.

08-07-2020, 07:19 PM - 2 Likes	#9
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,403	If you decide you like me to convert it, send me a pm. If you decide you want to convert it, after reading some of the threads on the subject feel free to post about your issues if you get stuck. As for the green ring, I suggest a milder type of glue... Perhaps contact cement. Look at any of the threads on loose rubber lens rings. Here's an example thread: Easy question: which glue for rubber focus ring?

08-07-2020, 10:00 PM	#10
pentaxus Site Supporter Join Date: Jun 2010 Location: Central Coast, CA Posts: 1,313	I vote with UncleVanya, use contact cement.

08-08-2020, 04:57 AM	#11
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	I would not use superglue. A more friendly contact cement like Pliobond would probably be better. Pliobond is often used to glue back the rubber parts on camera bodies and lens barrels.

08-08-2020, 03:52 PM - 1 Like	#13
monochrome Loyal Site Supporter Join Date: Mar 2008 Location: Working From Home Photos: Gallery \| Albums Posts: 26,276	Originally posted by Buckeyemikie Asking for suggestions on how to deal with quality issues on two of my lenses. 1) the green stripe ring on my DFA* 50 has fallen off. Luckily i found on the floor under my work table. Its 21 months since I bought it. It appears there was insufficient adhesive applied during assembly. If I can get Precision to answer their phone, I'll see what they say re repair cost. In the mean time, what do you think about just using super glue sparingly to reattach it myself? Would just leaving it off compromise AW protection? Don’t use superglue. The fumes could fog the lens elements. Use double stick scotch tape cut to fit. Originally posted by Buckeyemikie 2). The SDM on my 50-135 has failed again. First replaced years ago. Really don't want to spend another $300-400 to repair. I'd rather try to find a Sigma 50-150 instead. Would appreciate any thoughts/suggestions. Convert it to screwdrive. It focuses faster than the SDM and unless you are in a silent cathedral the noise is undetectable.

08-08-2020, 05:50 PM	#14
Buckeyemikie Site Supporter Join Date: Feb 2014 Photos: Gallery Posts: 503 Original Poster	Great input-thx again.As for the green ring, I thought I'd show you what I'm dealing with, so attached are macro shots showing the glue residue on the lens body and the green ring. Glue seems to be the way to go & I WON'T use superglue. The ring itself is intricately machined to match as close as possible the lens body-pretty amazing. The last two shots shows the flash hack I used to make the macros. Works really well with nature subjects, too. I'm still undecided on how to go with the 50-135. What does it cost to convert it to screw drive?.