[stevebrot]

SDM motor failure has been a hot topic on this for forum as of late. Since I don't currently own one of these lenses, I thought it might be useful for myself and for other potential purchasers to get some quantitative data. Sorry this poll does not have provision for people who have had multiple failures for a particularly model of lens.

Edit: It has been noted in several comments that there should have been a category for "cranky" SDM performance. Sorry that a third option was not included. I occurred to me that a small clarification should be in order regarding a definition for failure.

Bad SDM = Failure of the SDM motor requiring repair/replacement of the lens

This should not include:

• front/back focus issues
• hunting
• failure to lock focus
• other lens issues (e.g. centering defect)

/Edit

Steve

---

Last edited by stevebrot; 12-18-2009 at 09:02 AM.

[Ash]

You only want to know of failures Steve?
That'll just give you absolute data, not relative data which is more valuable.

[stevebrot]

You only want to know of failures Steve?
That'll just give you absolute data, not relative data which is more valuable.

This is my first time doing a poll. The options are a bit limited

I may be mistaken, but I think I included two conditions (good/bad) for each of the available SDM lenses. If you can think of a better way to structure the poll, post it up and I will ask the mods to take this one down.

Steve

[trd300gt]

I don't know if this was intentional, but the 17-70mm f4 isn't in the poll

[stevebrot]

I don't know if this was intentional, but the 17-70mm f4 isn't in the poll

Ackkkkk! I knew I missed one. Let me see if this is something that can be fixed!

Steve

[Ash]

A time period on how quickly SDM failed may be useful, but would blow the poll out with too many options. One of those more sophisticated polls where one option leads to multiple further qualifying options would be handy here.

This poll should do fine - the robustness of the data of course is limited, but reasonably useful nonetheless.

[stevebrot]

A time period on how quickly SDM failed may be useful, but would blow the poll out with too many options. One of those more sophisticated polls where one option leads to multiple further qualifying options would be handy here.

This poll should do fine - the robustness of the data of course is limited, but reasonably useful nonetheless.

Now if I can only figure out a way to add two more items. I have notified the mods to see what might be done.

Steve

[Peter Zack]

You have to ask Adam directly. Only he has the access to modify a poll.

[stevebrot]

You have to ask Adam directly. Only he has the access to modify a poll.

Thank you Peter. I will make a direct petition to the King...

Steve

[Peter Zack]

I don't know how to answer this poll. I have a DA*16-50mm that is brutally slow to focus at the weirdest times. It can lock in fast in nearly no light and then in daytime cloudy light, take forever to lock on. There is no reason to it. And I use the lens a lot for my working photography.

But my Backups are always nearby if the thing goes in "Moody Mode*"

*MM = I'm just not in the mood today. I heard you cursing me a few minutes ago so I'm going to be petulant and just range back and forth pretending that I'm looking for focus. The second the shot is missed (trust me I know exactly when that is) I'll lock on. Sucks to be you, Mr Camera Boy.

[Adam]

Please PM me next time you want to fix a poll, rather than reporting the post- thanks. DA 17-70 added!

[stevebrot]

I don't know how to answer this poll. I have a DA*16-50mm that is brutally slow to focus at the weirdest times. It can lock in fast in nearly no light and then in daytime cloudy light, take forever to lock on. There is no reason to it. And I use the lens a lot for my working photography.

But my Backups are always nearby if the thing goes in "Moody Mode*"

*MM = I'm just not in the mood today. I heard you cursing me a few minutes ago so I'm going to be petulant and just range back and forth pretending that I'm looking for focus. The second the shot is missed (trust me I know exactly when that is) I'll lock on. Sucks to be you, Mr Camera Boy.

Sorry, I was unaware of moody mode when I made up the poll.

Steve

[regor]

I can't really answer your question. First, I really see 3 categories of "experience" with SDM:

1. Never Failed (pretty obvious)
2. Have experienced non catastrophic failure(s) (i.e. failed to work from time to time, but not consistently, and not very often)
3. Catastrophic failure (i.e. stopped working altogether and required maintenance)

Even then this is still not portraying reality as usage (and conditions) has to be taken into account. for e.g. Never Failed... well..."I bought it yesterday and it hasn't failed yet !" that does not that compares to, "I have taken over 5,000 images and it never failed " ? or else... "It failed on me after using it for 5 hours in sub-zero temperatures with no protection / warming what-so-ever"

In other words, no simple survey will ever portray an accurate picture of the reliability of SDM. On top of that, to get significant statistics, you'd need to establish a minimum, RANDOM, sample. i.e. one needs to randomly target SDM Lens Owners as of course, those who experience failure are more motivated to answer your survey than those who did not, hence skewing the result.

My thoughts anyway...

[Deimo]

i don't vote, cause i ve got no more than 200 shots with DA* 300mm. Most where in a zoo at 5 degrees celsius.
No problems so far.

[Russell-Evans]

If you want some numbers, here are at least 50 failed lenses. There are actually more failed lenses as some of the posts in the list are for more than one lens.

https://www.pentaxforums.com/forums/831080-post170.html

Thank you
Russell