[paolotrabuio]

Go ahead and do this conversion ... well worth it !

In which way is possible to make this conversion? Need any special modification by repairing center or is possible to make it easily without sending the lenses to Pentax assistence?
I have mine that focus faster and more precise when used on old "ist Ds" (so with screwdriver) than on k5 by SDM, even if it can still work, just very lazy after some time without use it.

This lazy/sleepy behaviour is common on 16-50 and on 50-135. The 60-250 seems better, in this point bof view, even if not fast as Canon system, for example.

Please let me know in which way to convert the lens to screwdriver; I'm sure it will become perfect. Thanks

Paolo

[Rondec]

I don't think anyone knows the answer. I have owned a 16-50 for 7 years. It had SDM fail four or five months after I got it and was fixed under warranty and has shown no sign of problem since then. I will say that if screw drive sound doesn't bother you, the process for changing the lens over is fairly simple (I did it on my 50-135 which was acting sleepy and would take a little while to wake up).

Anyway, I really like mine.

[biz-engineer]

If you are buying new I would say the chance of the SDM failing is not much higher than any other in lens motor.

SDM failure is not a problem, it can be repaired, after two repairs, it just cost as much as buying a new lens. Never mind.

[Brucie]

Thank you all for your thoughts here.

[GlennG]

My 16-50 was purchased used - reportedly SDM repaired but with the new style motor. No problems in about 9 months since my purchase. I've no experience with the 20-40. Though not what you asked about, I've also a DA 17-70, and the SDM failed on that as well. Repair also done with the new motor. No problems since. I realize that many have experienced no SDM failures on the 16-50, but, in a purchase situation, I all but assume that it will fail if not already done so. I "value" a 16-50 with a replaced SDM higher than one that has not been replaced. A fall-back position is to just do the screw-drive conversion which seems to work for most.

[ronniemac]

I have the *16-50mm, the *55mm, the *60-250mm, and the 17-70mm - all SDM and to date have absolutely NO experience whatsoever of SDM failure, well done Pentax!



(Admittedly I have only had the 17-70 for four months and the other three lenses for just one month )

Grasping for wood with fingers and toes crossed.....

[BarryE]

Three SDM lenses. No failures. Maybe I'm lucky (until now, perhaps...). I take a lot of care with handling my kit and use these lenses regularly, just to keep the motors exercised - sometimes just for a few test shots if they've not had any recent proper usage. Maybe this approach helps ?

The 16-50 is a superb lens, but it's also an expensive and weak lens - it just seems to need to be learnt, I'd say, to get excellent results.

[Sholom]

I've had mine since 2011 without SDM issues. It gets light but fairly regular use. Optically it is excellent for a zoom of its range and complexity - great colors and plenty sharp if stopped down a bit. Definitely usable wide open if you need to. Flare and reflections can be an issue at 16mm if the sun is in or close to the frame, but I've seen far worse in other lenses. Contrast drops a bit going from 45 to 50mm, but its barely noticeable. Yes I also have the 43mm FA Limited and it is even sharper than is the zoom at 45mm, but I doubt any zoom could come close to the Limited. In any case, it takes great pictures, as a quick search through the Forum will show.

[gf1]

How likely is the SDM to fail in this lens? Anyone own a Pentax 16-50mm f2.8 lens that hasn't failed?

Considering this lens, or the 20-40mm Limited. Which is sharper?

Thank you.

Strongly recommend the 16-50mm, never had any issues with it since I got it 3 years ago, superb optic, solid, weather resistance, just a joy to use it. If the SDM failed, I'll convert it to screw drive.

[mholford]

In which way is possible to make this conversion? Need any special modification by repairing center or is possible to make it easily without sending the lenses to Pentax assistence?
I have mine that focus faster and more precise when used on old "ist Ds" (so with screwdriver) than on k5 by SDM, even if it can still work, just very lazy after some time without use it.

This lazy/sleepy behaviour is common on 16-50 and on 50-135. The 60-250 seems better, in this point bof view, even if not fast as Canon system, for example.

Please let me know in which way to convert the lens to screwdriver; I'm sure it will become perfect. Thanks

Paolo

It's a software fix. If you read the "definitive link" above, it details how to put an older pentax digital body into "debug mode" which allows you to load the lens internal programming onto your memory card, edit it (to always use the screwdrive, and ignore the SDM regardless of the camera body) and then re-load the changed software back into the lens. The lens is permanently changed regardless of what body it goes onto afterwards.(the software is inside the lens, not the camera).

[Scorpio71GR]

I have had my 16-50 for almost a year. I purchased mine new. So far it has never given me any issues. The build quality is quite exceptional. I have held the Tamaron and it does not compare. The Sigma my be close. If the 2.8 apeture is not important you may be happier with the 16-85. I had to take some time to get used to my 16-50. Once I get more pratice with it I found I really liked using it. Currently it, along with my 50-135, are some of my most used lenses. Mine is sharp right from 2.8.

[LaurenOE]

The 16-50 is awesome optically.
Buy one, and the first day, hack the bios/eprom to screw drive.
Save the bios/eprom in a safe place if you ever want to sell it or want to switch back.
Then, the lens will never let you down and you will never know of the inevitable.
They fail.
Not if, but when.



With that said, in screw mode, I use mine almost every single day.
Fantastic lens.

[paolotrabuio]

It's a software fix. If you read the "definitive link" above, it details how to put an older pentax digital body into "debug mode" which allows you to load the lens internal programming onto your memory card, edit it (to always use the screwdrive, and ignore the SDM regardless of the camera body) and then re-load the changed software back into the lens. The lens is permanently changed regardless of what body it goes onto afterwards.(the software is inside the lens, not the camera).

Thanks a lot. Very clear now.

Regards,

Paolo

[robjmitchell]

It's been reported that when Ricoh took over they started using a different SDM motor both for repairs and presumably in new batches of lenses. I bought mine new about 1 year ago, it came in a pentax branded box with Ricoh in tiny writing on the bottom of the box. If you do want silent over screw then watch out for Hoya stock, use your lenses regularly, and it probably cant hurt to rack the focus manually when you attach the lens to loosen it up. Otherwise go screwdrive and no worries!

[Ayrat]

How likely is the SDM to fail in this lens? Anyone own a Pentax 16-50mm f2.8 lens that hasn't failed?

Considering this lens, or the 20-40mm Limited. Which is sharper?

Thank you.

There is a comment I got from Pentax Service in Russian
There are (were) two issues with 16-50

1. Sudden SDM switching off. The issue has been resolved in lenses that is produced since 2013
2. There is design deficiency (or peculiarity). The SDM consists of two main parts: rotor and stator. They are separated with very small distance (about microns). So any stuff between rotor and stator increases friction and power of the piezoelectric elements is not enough to rotate the rotor.
   The sources of the stuff are: dust, chemical reaction (oxidation), lubricant evaporation. The latter two are originate from prolonged lens disuse. In order to avoid this it is enough to use the lens once per week.