[VAV]

Hello All!

K5 user here and I had a bad experience with SDM on my 16-50 - even after getting it repaired under warranty.
I am considering the full frame K1 and related lens. I am concerned about the SDM failing on the FF lens (15-30, 24-70). Any comments on SDM issues on these new FF lens? I am in India and the Pentax support here is even less than what I saw in the US so I need to be very cautious before investing further into the system.

I see that there is a newer 'DC' focus mechanism on the 70-200 and the 150-450 - is this a case of Pentax finally admitting to SDM issues?

Thanks,
Arvind.

[mcgregni]

It's still SDM but not as you know it!

The latest lenses use a newer design of focussing motor, and I don't think anyone here is expecting the same failures that befell the older type.

I certainly think it would have been good marketing to have ditched the SDM label, but Ricoh are not that attuned to such sensitivities.

[TER-OR]

Well, I just got a new DA300, so we'll see how it goes. The ticking noise is different from the silence of the 18-135. It's not loud, but noticeable.

[BullsOnParade81]

The SDM on the 24-70 and 15-30 is not the same as the DA* lenses. The 24-70 and 15-30 are really rebadged Tamron lenses.

[clickclick]

I am concerned about the SDM failing on the FF lens (15-30, 24-70)

I don't think these are SDM at all, I believe they are part of the DC motor classification like on the 150-450, and these have been very reliable. I would not worry about "SDM" on any modern lens. Also, while not formally stated, the consensus is that on the older SDM lenses that were prone to failure, the motor was upgraded in production at some point, so if you're buying a SDM lens like the 16-50 today, it should have a newer more robost motor.

[Aljech]

I don't think these are SDM at all, I believe they are part of the DC motor classification like on the 150-450, and these have been very reliable. I would not worry about "SDM" on any modern lens. Also, while not formally stated, the consensus is that on the older SDM lenses that were prone to failure, the motor was upgraded in production at some point, so if you're buying a SDM lens like the 16-50 today, it should have a newer more robost motor.

That's something I have been wondering also. From what I have read on the forum, we were some issues with the older SDM lenses, which could more or less very quickly end with a dead autofocus motor. However at some point, they change the SDM motor in the production such as it is much more reliable. What happened exactly? Did they change the motor completely? Because on the reviews of several DA*, the SDM autofocus was often described as a bit slow. Does the improvement also affect performances or really just the failure rate?

I also find it a bit hard to get the logic behind the autofocus engine used in the different lenses: you have DC motor, SDM, now also PLM. DA* uses SDM, some DFA* use also SDM (but a different one?) or DC (such as the 70-200). I thought that SDM was more adapted to bigger, heavier lenses compared to DC based on how they were integrated into the different lens classes, but the DFA* line proves me wrong. So I don't really get the logic on why not using the DC motor on all lenses, as it seems to be fast, silent and reliable. When you don't know much about lens design, it is sometimes hard to follow.

[clackers]

That's something I have been wondering also. From what I have read on the forum, we were some issues with the older SDM lenses, which could more or less very quickly end with a dead autofocus motor. However at some point, they change the SDM motor in the production such as it is much more reliable. What happened exactly? Did they change the motor completely? Because on the reviews of several DA*, the SDM autofocus was often described as a bit slow. Does the improvement also affect performances or really just the failure rate?

I also find it a bit hard to get the logic behind the autofocus engine used in the different lenses: you have DC motor, SDM, now also PLM. DA* uses SDM, some DFA* use also SDM (but a different one?) or DC (such as the 70-200). I thought that SDM was more adapted to bigger, heavier lenses compared to DC based on how they were integrated into the different lens classes, but the DFA* line proves me wrong. So I don't really get the logic on why not using the DC motor on all lenses, as it seems to be fast, silent and reliable. When you don't know much about lens design, it is sometimes hard to follow.

The SDM is just a label guys, don't stress.

The engineering has changed since the first two Pentax lenses with inbuilt motors (the 16-50 and 50-135).

[jatrax]

The 'SDM' label is just that, a label. Maybe trademarked? It is the name Pentax has used for a number of different motors. The ones in the 16-50 and 50-135 had a lot of problems prior to about 2012 when the motor was changed or strengthened. Few issues have been reported on lenses made after that date.

SDM is also on the 24-70 and 15-30 lenses but these use a Tamron design and motor which is completely different.

And now the new DFA*50mm uses an 'SDM' motor but from the descriptions so far it is completely different in design and concept from previous 'SDM' motors.

So saying 'SDM' is bad is now like saying all Ford cars are bad. It's just a label.

[aslyfox]

newest motor type

The HD Pentax DA 55-300mm F4.5–6.3 ED PLM WR RE is the first lens in brand history to use a pulse motor for autofocus, so we were especially interested to find out if it's a serious improvement over the DC and SDM lenses that came before. (Not to mention the ancient screw-drive motor in this lens's predecessor.) Read on for our full findings!

Read more at: HD Pentax-DA 55-300mm F4.5-6.3 PLM WR RE Review - Focusing | PentaxForums.com Reviews

current SDM type

The lens features two autofocus systems. On older bodies (predating the K10D), AF is driven by the traditional screwdrive shaft. On newer bodies, Pentax's in-lens Silent Drive Motor (SDM) is used, providing near-silent AF. In this review, we do not compare the speeds of the two systems, though we will say that Pentax's SDM motors are not known for their speed.
The SDM does feel accurate and responsive, however. A subtle whirring noise can be heard when listening closely in a silent environment, but for all practical matters the autofocus system is silent. It is therefore a big improvement over the dated screwdrive system.

Pentax's SDM motors have suffered from poor reliablity in the past. Fortunately, according to a survey we conducted in 2012, the SDM system on the DA* 60-250mm proved to be quite reliable. Only about 5% of 60-250mm users reported an SDM failure; failure rates for other lenses, such as the DA* 16-50mm, were as high as 30%. Recent reports from users and from Pentax engineers suggest that the SDM issues were resolved in late 2012, however.


Read more at: Pentax DA* 60-250mm F4 Review - Focusing | PentaxForums.com Reviews

DC type

The HD Pentax-D FA* 70-200mm features the newer silent DC motor which has proven to be far more reliable than SDM, as well as near-silent. In-lens focusing means that the lens won't autofocus with cameras older than the K10D (2006), which are quite dated by modem standards anyway. On the other hand, the newer AF systems are better adapted for contrast focusing using Live View.

Read more at: https://www.pentaxforums.com/reviews/hd-pentax-d-fa-star-70-200mm-f28/focusi...#ixzz58z4jlLLo

[stevebrot]

The SDM is just a label guys, don't stress.

Yep...All means is that the lens has Pentax' top-level in-lens focus system. As with similar designations at Sigma and Tamron, the actual implementations have evolved over time.


Steve

[leekil]

The engineering has changed since the first two Pentax lenses with inbuilt motors (the 16-50 and 50-135).

What about the 55mm?

[jatrax]

What about the 55mm?

I'm not sure I remember ever seeing any issues with the 55mm. The SDM motors used in the DA* lenses were not all the same. Some had issues, (16-50 and 50-135) others not.

[Adam]

Hello All!

K5 user here and I had a bad experience with SDM on my 16-50 - even after getting it repaired under warranty.
I am considering the full frame K1 and related lens. I am concerned about the SDM failing on the FF lens (15-30, 24-70). Any comments on SDM issues on these new FF lens? I am in India and the Pentax support here is even less than what I saw in the US so I need to be very cautious before investing further into the system.

I see that there is a newer 'DC' focus mechanism on the 70-200 and the 150-450 - is this a case of Pentax finally admitting to SDM issues?

Thanks,
Arvind.

The original SDM in the DA* 16-50mm, 50-135mm, 60-250mm, 55mm, and DA 17-70mm is the one prone to failure. Later lenses branded "SDM" all use a different motor which seems to be just as reliable as screwdrive, if not better. Same goes for DC.

[robjmitchell]

SDM = sonic drive motor. They come in both micromotor and ring forms.
15-30 and 24-70 tamron ring type, no problems. DFA*50 new ring motor from pentax.
Da* 16-50, 50-135, 60-250, 55, 300, Da 17-70. Micromotor with problems on 16-50, 50-135, 17-70 in particular. The 16-50 and 50-135 can be hacked and converted to screw mount. (With an older body) 17-70 and 55 cannot be converted.
Failure seems to be related to infrequent use.
There is a rumour the 16-50 and 50-135 will be updated with DC motors towards the end of the year.

Note DC (direct current) motors also come in micro and ring types. Micro motors drive a screw/gears, while ring motors have more torque/power.

[VAV]

Thanks all for your kind responses.