Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-04-2010, 02:58 PM   #121
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,245
QuoteOriginally posted by juu Quote
The only way you would be convinced that there is a problem is if you get the reliability data.
I didn't say that's this is the only way to convince me.

QuoteOriginally posted by juu Quote
But there isn't any way to get that data.
The fact that I don't have a suggestion of how to get that data doesn't mean there isn't any way to get the data.


QuoteOriginally posted by juu Quote
You put the burden of proof on us fully well knowing it is an impossible task.
I don't put any burden of proof on anyone. I just said if one cannot know something for sure, one should not purport certainty.


QuoteOriginally posted by juu Quote
That is like someone in the 15th century claiming that the only way he would believe the earth is round is if he'd see photographs of it from space.
I'm not someone who asks for a difficult proof despite the fact that there are easy ones available (the ancient Greeks already knew how to demonstrate that the earth cannot be flat with something simple as deep wells). I'm someone who refuses to confuse presumption with knowledge.

02-04-2010, 03:27 PM   #122
juu
Veteran Member
juu's Avatar

Join Date: Sep 2008
Posts: 680
QuoteOriginally posted by Class A Quote
I didn't say that's this is the only way to convince me.
It was the only way you mentioned, and it seems logical to assume that you stated the most reasonable way of convincing you. Even so it turns out not reasonable at all as the data cannot be obtained.

What other ways do you suggest then?


QuoteQuote:
The fact that I don't have a suggestion of how to get that data doesn't mean there isn't any way to get the data.
Well, you cannot even suggest how to go about obtaining the data, while you still require that data before you think we can make up an opinion on the SDM failures.

Do you see how ridiculous that position is?

QuoteQuote:
I don't put any burden of proof on anyone.
You have stated that "despite the apparently high number of victims, we have cannot have any certainty about the existence of a major problem" and "the numbers of failure reports are below statistical significance".

However, when asked when can it be reasonably certain that there is a major problem with the SDMs, you have essentially requested us to provide proof you know is impossible to obtain.

In essence, you are putting the burden of proof on us, in a way you know full well cannot be satisfied. Isn't that great?


QuoteQuote:
I'm not someone who asks for a difficult proof despite the fact that there are easy ones available.
Yes, you are instead someone who asks for impossible proof when there are no easy ones available.

QuoteQuote:
I'm someone who refuses to confuse presumption with knowledge
Near certainty often has to suffice if total certainty cannot be obtained.
02-06-2010, 05:07 AM   #123
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,245
QuoteOriginally posted by juu Quote
It was the only way you mentioned, and it seems logical to assume that you stated the most reasonable way of convincing you.
That's not logical in my book.

QuoteOriginally posted by juu Quote
...you have essentially requested us to provide proof you know is impossible to obtain.
So you agree with me that there is no proof and you go even further and state that proof is impossible to obtain, but you still insist on knowing something without that proof?

Of course it is fine if someone personally decides not to buy an SDM lens because they are "near certain" that it isn't a good idea. But I don't think it is fine if someone spreads news about an allegedly "know problem" when all they have is circumstantial evidence that isn't suitable to create something even close to "near certainty".
02-06-2010, 06:25 AM   #124
juu
Veteran Member
juu's Avatar

Join Date: Sep 2008
Posts: 680
QuoteOriginally posted by Class A Quote
That's not logical in my book.
When you ask somebody how to get from New York to Washington is it not logical to assume he will provide a fairly direct route instead of guiding you through Las Vegas?

Anyway, asking you again:
What other ways do you suggest then?

QuoteQuote:
So you agree with me that there is no proof and you go even further and state that proof is impossible to obtain, but you still insist on knowing something without that proof?
Let me qualify that as you seem hell-bent on misinterpreting my position.

It is not in our power to obtain absolute proof as that would require data that Pentax won't release. You know it, we know it.

Still, based on the data available, we can be near certain that there is a problem with SDM.

The fact that you seemingly require us to produce absolute proof doesn't change that.

Do you follow so far?

QuoteQuote:
Of course it is fine if someone personally decides not to buy an SDM lens because they are "near certain" that it isn't a good idea. But I don't think it is fine if someone spreads news about an allegedly "know problem" when all they have is circumstantial evidence that isn't suitable to create something even close to "near certainty".
You say there isn't enough evidence to get to "near certainty", I and most other posters in this thread seem to think there is.

Obviously when things go from "possible" to "more likely than not" to "near certain" to "very certain" etc. is somewhat individual.

What is your estimate of the probability that SDM lenses have two times or higher failure rate than non-SDM lenses in the first four years of ownership after the one-year warranty period?

Based on the information available, my estimate is 99%+. What's yours?

02-07-2010, 10:04 AM   #125
Inactive Account




Join Date: Dec 2008
Posts: 35
Same issue with my 50-135

Recently I've noticed my lens does not focus at all in auto on my K-7--at least when I first put it on the camera. It has been a couple weeks since I last tried it and then when I pulled it out today I had the problem. After switching between AF and MF, taking the lens on and off, switching to live view etc. it eventually starts working--5 minutes later. Should I send it in or do all the SDM lens have this problem? Is there a firmware update?
02-07-2010, 10:33 AM   #126
Veteran Member
bc_the_path's Avatar

Join Date: Mar 2007
Location: Ankara, Turkey
Photos: Gallery
Posts: 390
bsimon,
Those were the first symptoms of my 50-135mm.
Its SDM failed and I had to pay to get it fixed.
If yours is still under warranty, do not wait a minute and send it for repair.
Unfortunately, you are likely to labeled as a member of he "vocal minority" here since you say you have a strangely behaving SDM lens

Last edited by bc_the_path; 02-07-2010 at 10:39 AM.
02-07-2010, 11:09 AM   #127
New Member
ooCRIMoo's Avatar

Join Date: Feb 2009
Location: Richmond, VA
Posts: 8
vocal minority, table for 1 please

add me to the vocal minority (long time lurker but rare poster) - The day before it's year warranty expired, my 16-50 stopped focusing. After messing with it awhile, it started working again though with a scary new chirping sound. I called Pentax and sent the lens to CRIS, who replaced the SDM motor under warranty. I just got it back and it's working great like before....but now my 50-135 is doing the exact same thing! It's only 8 months old, and really hasn't been used much. How extremely frustrating, now I've got almost 2 grand tied up in gear which may or may not function for a year at a time without repair - this is not the Pentax I signed up with. My 20 year old M series 100mm macro still works wonderfully, even my old heavily used DA 18-55 I kit lens is more reliable, loose focus ring and all. I should mention that I'm extremely cautious with my equipment, borderline neurotic when it comes to packing stuff securely and handling it carefully. At this point, I'm going to wait until the end of my warranty period to send in the 50-135, hopefully the replacement motor will give me at least one more year of use. I'm not expecting more at this point.

I love my Pentax camera bodies (K20, K100, K110) and most of my lenses, and will continue shooting them, but my event work is too fast paced to mess with changing primes...so I've been pricing out an addition of another system. Pentax pulled me in with the best value around, however if I can pay more for a lens that won't fail inside a year then I certainly will.
02-07-2010, 03:32 PM   #128
Inactive Account




Join Date: Dec 2008
Posts: 35
Thanks for the replies. I have some more time left on my warranty so I'm going to see if it happens again before sending it in...

02-08-2010, 06:22 AM   #129
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,245
QuoteOriginally posted by ooCRIMoo Quote
Pentax pulled me in with the best value around, however if I can pay more for a lens that won't fail inside a year then I certainly will.
It may be a "vocal minority" only...
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
button, contacts, da*, k-7, k-mount, lens, lenses, months, pentax lens, sdm, shutter, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Do SDM problems affect your purchasing axl Pentax SLR Lens Discussion 167 04-25-2010 02:12 AM
DA*50-135mm f2.8 SDM Problems / No Problem rustynail925 Pentax SLR Lens Discussion 30 03-22-2010 06:08 PM
Uh oh, I think my 17-70mm SDM is having problems Big G Pentax SLR Lens Discussion 30 02-17-2010 02:23 PM
Is there alot of problems with the SDM AF motor? NorthPentax Pentax SLR Lens Discussion 9 01-30-2009 12:29 PM
AF problems with SDM lenses on K20D? tcom Pentax DSLR Discussion 19 07-18-2008 07:55 AM



All times are GMT -7. The time now is 03:46 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top