Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-02-2011, 12:04 PM   #1
Veteran Member




Join Date: Sep 2006
Location: Netherlands
Photos: Gallery
Posts: 908
DA*16-50, three copies , different behaviour.....

On the last day of 2010 my trusty 16-50 gave up after much abuse.

I sent it for repair under warranty and... nothing...... with carnaval comin up I panicked and found a good deal and got me anoher one...
Today both the new one and my old one arrived...

Tried all, my old one , a beauty, spot on and fast (they replaced AF motor) . Serial no. 9033 etcetc. Then the new one.... It is spot on but oh so slow..... serial no. 9020..... Oddly enough a friend offered me to borrow his which he got last week (other store).... also slow.... bought new serial no/ 9022.....

My repaired one is faster than I can remember, the new ones are slower than the old one was...

03-02-2011, 03:59 PM   #2
JHD
Veteran Member




Join Date: Jan 2010
Photos: Albums
Posts: 1,407
"Afschuwelijk!"
03-02-2011, 04:53 PM   #3
Pentaxian
philbaum's Avatar

Join Date: Oct 2007
Location: Port Townsend, Washington State, USA
Posts: 3,659
QuoteOriginally posted by janneman Quote
On the last day of 2010 my trusty 16-50 gave up after much abuse.

I sent it for repair under warranty and... nothing...... with carnaval comin up I panicked and found a good deal and got me anoher one...
Today both the new one and my old one arrived...

Tried all, my old one , a beauty, spot on and fast (they replaced AF motor) . Serial no. 9033 etcetc. Then the new one.... It is spot on but oh so slow..... serial no. 9020..... Oddly enough a friend offered me to borrow his which he got last week (other store).... also slow.... bought new serial no/ 9022.....

My repaired one is faster than I can remember, the new ones are slower than the old one was...
that apparently is not unusual. benjikan, a French member, reported sending both his SDM lenses in for preemptive repair, maybe 8 months ago, and then reported they were much faster after coming back from repair. it would really be nice for Pentax to explain what is going on
03-02-2011, 04:56 PM   #4
Veteran Member
sewebster's Avatar

Join Date: Jun 2008
Location: Vancouver, BC
Photos: Gallery
Posts: 533
Could be that different tightness in the assembly and/or lubrication results in different focussing speeds when subjected to the same motor torque.

03-02-2011, 05:40 PM   #5
Junior Member




Join Date: Jan 2009
Location: Berlin, DE
Posts: 30
I had two samples of this lens, both recent with 904xxxx s/n. No issues with focusing speed in either of them; however, the first sample required an AF adjustment of +3 and even after never quite locked consistently on where I wanted it to where AF points other than the central one were selected. Besides, the entire right side was slightly blurry with more CA than the left side had.

My second sample is just fine: zero adjustment, locks exactly where pointed all the time no matter which focusing point I use. Both sides equally sharp; border resolution is visibly higher than it was with the first sample.

It does appear that Pentax manufacturing tolerances are just terrible, at least with this particular model (although I've heard of much sample variance with e.g. 17-70/4, but none with the 16-45/4. Go figure.)
03-02-2011, 07:37 PM   #6
Site Supporter
SpecialK's Avatar

Join Date: Dec 2006
Location: So California
Photos: Gallery
Posts: 14,687
QuoteQuote:
benjikan, a French member, reported sending both his SDM lenses in for preemptive repair, maybe 8 months ago, and then reported they were much faster after coming back from repair.
If I'm not mistaken, Benjikan is Canadian, just living/working in France. One of his repaired lenses died in mid-shoot - he posted about it.
03-03-2011, 01:16 AM   #7
Veteran Member




Join Date: Sep 2006
Location: Netherlands
Photos: Gallery
Posts: 908
Original Poster
QuoteOriginally posted by sewebster Quote
Could be that different tightness in the assembly and/or lubrication results in different focussing speeds when subjected to the same motor torque.
Nope, repairslip says "new AF motor and check and calibration".
So I amnow incline to keep it as a back up, use it mainly in daylight ( where AF is not so much of a problem) and hope it breaks down so I can send it in for repair and get a new AF motor.... If I send it in just now I will get another replacement without a new AF motor..
03-03-2011, 10:58 PM   #8
Veteran Member
sewebster's Avatar

Join Date: Jun 2008
Location: Vancouver, BC
Photos: Gallery
Posts: 533
QuoteOriginally posted by janneman Quote
Nope, repairslip says "new AF motor and check and calibration".
So I amnow incline to keep it as a back up, use it mainly in daylight ( where AF is not so much of a problem) and hope it breaks down so I can send it in for repair and get a new AF motor.... If I send it in just now I will get another replacement without a new AF motor..
Yeah, they have to take it apart to replace the motor, and when they reassemble it, they might change how tight it is.

03-04-2011, 01:24 PM   #9
Veteran Member
benjikan's Avatar

Join Date: Jan 2007
Location: Paris, France
Photos: Gallery
Posts: 4,309
QuoteOriginally posted by philbaum Quote
that apparently is not unusual. benjikan, a French member, reported sending both his SDM lenses in for preemptive repair, maybe 8 months ago, and then reported they were much faster after coming back from repair. it would really be nice for Pentax to explain what is going on
Um...I am actually Anglo Canadian living in Paris, France.
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!
k-mount, pentax lens, slr lens, spot
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
After getting 2 bad copies, what next? shang Pentax SLR Lens Discussion 11 07-29-2010 01:34 AM
Do you own multiple copies of the same lens? Just12hvFun Pentax SLR Lens Discussion 66 05-21-2010 04:45 PM
Substandard Copies? NecroticSoldier Pentax SLR Lens Discussion 6 04-03-2010 07:43 AM
Manual Copies Fl_Gulfer Pentax Camera and Field Accessories 0 08-18-2008 02:57 PM
Strange Behaviour Tom Lusk Post Your Photos! 7 09-16-2007 05:10 PM



All times are GMT -7. The time now is 07:09 PM. | 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