I have had some rather unpleasant experiences with fragile HSM motor in Sigma lenses in the past. Since then, I have avoided lenses with built-in motor. I am now considering getting a Pentax 18-135 as a Christmas gift for someone who is very enthusiastic about this lens. I, however, do not share this enthusiasm, given my experiences the HSM of Sigma.

My question: is the motor to be found in Pentax lenses built along the same lines as Sigma's HSM?

I have doubts about the mechanical durability/reliabilty of lenses with built-in motor in general. Anyone else who shares this scepticism?

Dom

[GaryH]

All lenses with motors like HSM or SDM can fail at some point and probably will. Gone are the days of a 20-30 year old perfectly operational AF lens. That will be less likely to find vs a old manual focus lens from 20-30 years ago. That being said, I would not care to go back to manual focusing all the time and I am willing to accept the possibility of failure. I currently have no less than 6 lenses with SDM or DC motors and they are all working fine. I have only had one SDM motor go out on me and I had it repaired and went on about my business.
Saying all that, the DC motor of the 18-135mm is probably one of the most reliable in the Pentax line-up.

YMMV

All lenses with motors like HSM or SDM can fail at some point and probably will. Gone are the days of a 20-30 year old perfectly operational AF lens. That will be less likely to find vs a old manual focus lens from 20-30 years ago. That being said, I would not care to go back to manual focusing all the time and I am willing to accept the possibility of failure. I currently have no less than 6 lenses with SDM or DC motors and they are all working fine. I have only had one SDM motor go out on me and I had it repaired and went on about my business.
Saying all that, the DC motor of the 18-135mm is probably one of the most reliable in the Pentax line-up.

YMMV

That's not very encouraging.

The old school AF lenses never failed me. Guess I should get the 18-135 enthusiast to consider an alternative.

[savoche]

I wouldn't worry about the DC motor - and I don't, having a 18-135 myself. You'll find lots of stories about SDM motors breaking (even though that's supposed to be a problem of the past), but not many have complained about the DC motors that I have seen.

Of course, the old and noisy screw drive AF doesn't have any motor at all. Fair enough if you want to stay with those, but I must say I really like the speed and silence of the DC driven focusing of the 18-135.

[Adam]

I have had some rather unpleasant experiences with fragile HSM motor in Sigma lenses in the past. Since then, I have avoided lenses with built-in motor. I am now considering getting a Pentax 18-135 as a Christmas gift for someone who is very enthusiastic about this lens. I, however, do not share this enthusiasm, given my experiences the HSM of Sigma.

My question: is the motor to be found in Pentax lenses built along the same lines as Sigma's HSM?

I have doubts about the mechanical durability/reliabilty of lenses with built-in motor in general. Anyone else who shares this scepticism?

Dom

The 18-135mm's DC system is probably just as reliable as screwdrive, because it just uses a ring motor. Nice and simple

I wouldn't worry about the DC motor - and I don't, having a 18-135 myself. You'll find lots of stories about SDM motors breaking (even though that's supposed to be a problem of the past), but not many have complained about the DC motors that I have seen.

Of course, the old and noisy screw drive AF doesn't have any motor at all. Fair enough if you want to stay with those, but I must say I really like the speed and silence of the DC driven focusing of the 18-135.

I have not read any reports of 18-135 failures either; but this got me a bit worried:

How long would your HSM motor last?: Third Party Lens Talk Forum: Digital Photography Review

[VoiceOfReason]

My 18-135 has given me exactly zero problems.

[sterretje]

Guess I should get the 18-135 enthusiast to consider an alternative.

The engine of my Freelander 2 ceased before 100000km. You've just convinced me to buy a bicycle instead of another car

[Fat Albert]

I have an 18-135 that I love and it's given me zero problems. DC motor and SDM aren't the same thing, though?

[Joojoo2010]

Those lenses with motors must be handled more carefully cos motor is weakest point to broke with hits. I did read this from somewhere and did believe, do not start to trought stones on me pls

[Stone G.]

Adam has said it: The DC motor in the 18-135mm is probably just as reliable as a screw drive. I might add, based upon my own experieces: Only smoother, quieter and nicely fast in comparison with my screw-drive zooms.

DC and SDM are definitely not the same thing and I don't recall having heard about "DC-failure" as a problem. I use my 18-135 an awful lot, and it has never let me down!

[pete-tarmigan]

I have had some rather unpleasant experiences with fragile HSM motor in Sigma lenses in the past. Since then, I have avoided lenses with built-in motor. I am now considering getting a Pentax 18-135 as a Christmas gift for someone who is very enthusiastic about this lens. I, however, do not share this enthusiasm, given my experiences the HSM of Sigma.

My question: is the motor to be found in Pentax lenses built along the same lines as Sigma's HSM?

I have doubts about the mechanical durability/reliabilty of lenses with built-in motor in general. Anyone else who shares this scepticism?

Dom

I found only one report of the DC motor failure on pentaxforums:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/204704-af-d...5-wr-lens.html

Mine is quick, silent, and trouble-free after 3 years of regular use.

[pete-tarmigan]

I found only one report of the DC motor failure on pentaxforums:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/204704-af-d...5-wr-lens.html

Mine is quick, silent, and trouble-free after 3 years of regular use.

Make that 2 reports of DC motor breakdown:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/229389-pent...essions-4.html

However, 2 reports is still a small number.

[normhead]

Hmmmm, I was going to say two reports, but I never thought of looking them up. Mine is almost 3 years old. I've had no problems at all… I have 7000 keepers still on my computer that I took with it, I'm guessing that's at least 20,000 images, and probably a lot more. I have no where near a 3:1 ratio, tossed images to keepers.

[Kozlok]

My 18-135 is at CRIS right now because the AF motor started making a high pitched noise, but only when focusing near to far. It still focused fine, and the noise wasn't that loud, but thought I should send it in before my 1 year warranty expired.