What does a Screwdrive Converted Pentax DA* 50-135mm F2.8 lens sound like?

Some people asked 'how loud' is a screwdrive converted Pentax DA* 50-135mm F2.8 lens. So I made a Youtube video comparing the the converted Pentax DA* to a Vivitar 100mm F3.5 macro (The plastic fantastic). It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

Pentax DA* 50-135mm F2.8 Screwdrive Sound Comparison (youtube video)

and is your experience in the field positive?, thanks for sharing by the way.

cheers,

Rene

OnTheWeb wrote:

Some people asked 'how loud' is a screwdrive converted Pentax DA* 50-135mm F2.8 lens. So I made a Youtube video comparing the the converted Pentax DA* to a Vivitar 100mm F3.5 macro (The plastic fantastic). It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

Pentax DA* 50-135mm F2.8 Screwdrive Sound Comparison (youtube video)

Hold the phone there sport. Failure is NOT inevitable. I've had my 50-135 for 5 trouble free years and expect it to last indefinitely. Likewise, the DA300 and the DA17-70 have had no problems for me whatsoever. I do wish the 50-135 was a bit faster in its performnce, but he optics are stellar.

I get it that your lens failed, and that would be a major bummer. I am fairly confident that the majority of the DA50-135 do not fail. Too many do, but not the majority.

I did the conversion just to see what it was like.  yes they work screwdrive, sound like screwdriven lenses BUT my 16-50 suddenly had a huge focus issue.  Needed +10 adjustment on camera body.  The 50-135 needed no adjustments...strange.

Changed them back to SDM and focus is spot on with no adjustments needed.  I am wondering if this is why Pentax never has released the option to select SDM or Screwdrive.  Imagine the complaints they would have if your perfectly focusing lens suddenly needed adjustment that wa possibly outside of the in-body adjustment feature

Well I didn't intend this to be interpreted as a Pentax bashing thread... I'm a Pentax owner too, and this was the 2nd DA* 50-135mm that I've owned.

It was meant to be positive, demonstrating that a screwdrive DA* is not a bad thing at all and maybe even encourage owners that have issues that there is a very viable alternative.

OPTMEKX7 wrote:

and is your experience in the field positive?, thanks for sharing by the way.

cheers,

Rene

My experience has been positive, and I've owned the SDM-working version as well as the screwdrive converted version.   At the end of the day if it locks sharp focus and has great optics I'm happy.

OnTheWeb wrote:

Some people asked 'how loud' is a screwdrive converted Pentax DA* 50-135mm F2.8 lens. So I made a Youtube video comparing the the converted Pentax DA* to a Vivitar 100mm F3.5 macro (The plastic fantastic). It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

Pentax DA* 50-135mm F2.8 Screwdrive Sound Comparison (youtube video)

OK, so I haven't yet had SDM failure on my two DA* lenses. I don't know if it's "inevitable" or not but when and if that day comes, what's involved in converting it to screw drive? How expensive is that, vs. having the SDM repaired? Since neither is under warranty after a year, it shouldn't affect the warranty, but how does it affect the quality and/or speed of AF? Obviously it's a bit noiser, as the SDM is pretty silent. But if SDM does turn out to be something that fails, and fails again, I'd like to know what my options are.

Jeff

Hi:

Talking about the inevitability of failure may be a bit pessimistic and/or conclusory, but I think it is accurate.

I love my Pentax gear, and baby all of it, but the SDM in my DA* 16-50 failed twice and in my DA* 60-250, too--thankfully just prior to the end of the first year for the DA* 60-250.  The second repair of the DA* 16-50 was out of warranty, but Pentax fixed it for free.

Both are good /excellent optically, but the SDM, well..........

My first K5 would not focus with any of my lenses, my second K5 had the sensor stains.

My first K5ii had a version of the mirror flapping--but rather than machine gunning, the mirror/shutter/prism would not reset properly and I had a double shutter/jumping shutter whereby two frames would be taken per a single shutter press and neither image was in focus. The camera could not be repaired and I was given a new model.

Is this a Pentax issue? No. It is a modern mass produced electronics issue (with all of the pros and cons that goes along with the mass production of consumer electronics).

Pentax has a K3 issue--though, it appears to involve a much smaller number of cameras than the Nikon 600 spots problem.

So, "once your SDM fails, which is inevitable" is correct in spirit, I think, and a good and appropriate warning to potential customers, even if it really will not happen in every instance, or even most.

candgpics wrote:

So, "once your SDM fails, which is inevitable" is correct in spirit, I think, and a good and appropriate warning to potential customers, even if it really will not happen in every instance, or even most.

DA* 16-50 7 years old no failure

da* 55 4 years old no failure

da* 300 6 years old no failure

da* 50-135 7 years old failed at 4 years was replaced

That gives an MTBF of 24 years !

If you take all available stats and translate them into 'failure' rate you get

da*55 = 3-5%

da*300 = 2-4%

da* 50-135 = 8-10%

da* 16-50 = 8-12%

The industry 'mean' is 2-4% so though the first SDM lens have higher than average for the industry they also are within tolerance for a new technology at release and one would expect if you limited the data used to recent years they would now be within except able limits.

Though it easy to rant 'those bxstards with their crappy SDM' when you have a failed unit the facts are different and show why Pentax/Ricoh have not and will not take any action to fix web mythology rather than real facts.!

SDM is more prone to failure than screw drive but so is HSM/USM etc etc.

SO the correct statement would be in the unlikely event your SDM fails !

To imply that SDM failure is inevitable or even probable is foolish an the facts do not support it.

JeffAHayes wrote:

OnTheWeb wrote:

Some people asked 'how loud' is a screwdrive converted Pentax DA* 50-135mm F2.8 lens. So I made a Youtube video comparing the the converted Pentax DA* to a Vivitar 100mm F3.5 macro (The plastic fantastic). It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

Pentax DA* 50-135mm F2.8 Screwdrive Sound Comparison (youtube video)

OK, so I haven't yet had SDM failure on my two DA* lenses. I don't know if it's "inevitable" or not but when and if that day comes, what's involved in converting it to screw drive? How expensive is that, vs. having the SDM repaired? Since neither is under warranty after a year, it shouldn't affect the warranty, but how does it affect the quality and/or speed of AF? Obviously it's a bit noiser, as the SDM is pretty silent. But if SDM does turn out to be something that fails, and fails again, I'd like to know what my options are.

Jeff

Hi Jeff

conversion costs nothing you need the correct camera (one of the older generation) and simlply change the lens Firmware.

using something like a k5,k7,kx etc the procedure is

1 switch camera in to debug with something like pk-tether (not required for k20)

2 use file on SD card to fully enable debug menu

3 enter debug menu export lens firmware

4 using note pad alter required field (see link)

5 import new altered Fw

6 enjoy or not depending on your noise tolerance and lens usage

http://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/208353-how-deactivate-sdm-allow-screw-drive-autofocus-da-16-50mm-f-2-8-a.html

I'm surprised that no one has referred to the SDM self repair procedures that are out there.

Like this - a guide for this DIY repair online

I did this a couple of years ago, after the $300.00 Pentax Japan repair failed, and have been using SDM focus ever since. I'm not alone.

On a first batch 50-135 btw.

And if it fails again, I'l probably have another go at it.

Go, Daniel Ricciardo!

AB

awaldram wrote:

DA* 16-50 7 years old no failure

da* 55 4 years old no failure

da* 300 6 years old no failure

da* 50-135 7 years old failed at 4 years was replaced

That gives an MTBF of 24 years !

How did you calculate that?

MartinsB wrote:

awaldram wrote:

DA* 16-50 7 years old no failure

da* 55 4 years old no failure

da* 300 6 years old no failure

da* 50-135 7 years old failed at 4 years was replaced

That gives an MTBF of 24 years !

How did you calculate that?

7+7+4+6 =24 years with 1 failure 24/1 = 24

Calculating MTBF
MTBF sounds simple: the total time measured divided by the total number of failures observed. For example, let's wring out a new generation of 2.5-in. SCSI enterprise hard drives. We run 15,400 initial units for 1,000 hours each (thus our tests take a little less than six weeks), and we find 11 failures. The MTBF is (15,400 x 1,000) hours/11, or 1.4 million hours. (This is not a hypothetical MTBF; it represents current drive technology in 2005.)

http://features.techworld.com/operating-systems/1944/mtbf-what-lifespan-can-you-expect/?intcmp=ros-md-acc-p-ft

brandrx wrote:

OnTheWeb wrote:

It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

I completely disagree with this part of your statement, " ...once your SDM fails, which is inevitable."

If you had written, "...if your SDM fails.", and left off, "...which is inevitable." then your post makes some sort of sense. Otherwise it just seems to me to be Pentax bashing.

Just my opinion.

Hi Ron.

Thanks for suffixing your post with "Just my opinion."  That's more than fair.

The "which is inevitable" is open to debate and certainly not proven.  It seems like hyperbole to me.  That is something this forum has plenty of.

Time will tell how many of these SDM systems are still functioning 10 years into their lives but I fail to see why it is necessary to "spin" the forum narrative in favor of Pentax.

There are a few people who will counter any reports of SDM failures with something like, "Well, I have an SDM lens that has not failed so this is a perception problem, not a real problem."  Do you jump on those people?

My hunch is that there will be examples of SDM lenses that last more than a decade without failure.  The 50-135 seems to have lower reliability so fewer working examples of that lens may make their 10th anniversary without repair, we won't know.  That could be due to the focal length lending itself to being used less frequently or it could be a design issue.  Either way, there are plenty of reports of failures and you don't have to go beyond this group to find plenty of those reports.

This man had a failed lens.  The SDM issue is real.  Pentaxians need to deal with it.

Ron

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awaldram wrote:

MartinsB wrote:

awaldram wrote:

DA* 16-50 7 years old no failure

da* 55 4 years old no failure

da* 300 6 years old no failure

da* 50-135 7 years old failed at 4 years was replaced

That gives an MTBF of 24 years !

How did you calculate that?

7+7+4+6 =24 years with 1 failure 24/1 = 24

These are different products (even if some components are the same) and such calculation appears to be useless.

MartinsB wrote:

awaldram wrote:

MartinsB wrote:

awaldram wrote:

DA* 16-50 7 years old no failure

da* 55 4 years old no failure

da* 300 6 years old no failure

da* 50-135 7 years old failed at 4 years was replaced

That gives an MTBF of 24 years !

How did you calculate that?

7+7+4+6 =24 years with 1 failure 24/1 = 24

These are different products (even if some components are the same) and such calculation appears to be useless.

We are discussing SDM failure not individual lenses , all are SDM so the calculation is valid for my lens.

The statement posed was 'SDM failure is inevitable' my experience proves the statement is false.

no more no less it stands on its own facts something often in short supply.

Tom__Brown wrote:

brandrx wrote:

OnTheWeb wrote:

It was captured with decent quality microphones so hopefully this gives you some idea what to expect after you convert your lens to screwdrive once your SDM fails, which is inevitable.

I completely disagree with this part of your statement, " ...once your SDM fails, which is inevitable."

If you had written, "...if your SDM fails.", and left off, "...which is inevitable." then your post makes some sort of sense. Otherwise it just seems to me to be Pentax bashing.

Just my opinion.

Hi Ron.

Thanks for suffixing your post with "Just my opinion." That's more than fair.

The "which is inevitable" is open to debate and certainly not proven. It seems like hyperbole to me. That is something this forum has plenty of.

Time will tell how many of these SDM systems are still functioning 10 years into their lives but I fail to see why it is necessary to "spin" the forum narrative in favor of Pentax.

There are a few people who will counter any reports of SDM failures with something like, "Well, I have an SDM lens that has not failed so this is a perception problem, not a real problem." Do you jump on those people?

My hunch is that there will be examples of SDM lenses that last more than a decade without failure. The 50-135 seems to have lower reliability so fewer working examples of that lens may make their 10th anniversary without repair, we won't know. That could be due to the focal length lending itself to being used less frequently or it could be a design issue. Either way, there are plenty of reports of failures and you don't have to go beyond this group to find plenty of those reports.

There is a good chance the 16-50 and 50-135 have more failures because they sell in larger numbers than the other lens, They've also been around longer.

There will be more 10 year old 50-135 and 16-50 still running purely because more are made and sold, it makes no odd unless your look at number of failures Vs lens sold.

As Pentax do not release these figures you can only get an approximation of failure rates by educated guessing.

This man had a failed lens. The SDM issue is real. Pentaxians need to deal with it.

Is it,? again show me your figure that prove SDM 'issue is real.?

Plenty have SDM failure me included that doesn’t mean that SDM issue is real unless you can show figures that show SDM is more failure prone than anyother ultrasonic drive system.

This you will fail to-do as sticktion is an issue of piezo drives not SDM unduly

I'm happy to believe you and join a crusade to sink Pentax but not on the say so of web zealots with no facts to back them up.

Web forums are a nest of misinformation due to human nature.

Those with fully functional SDM are taking picture not posting.

Those with failed SDM seek out somewhere to vent.

Ron

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Ron - 'We don't have time to go take pics this afternoon Carl.'
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'Keep your eyes looking forward. However, glance back now and then to see where you've come from. It will put a smile on your face.' ~ brandrx

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