Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-13-2017, 10:32 AM   #1
Site Supporter
Site Supporter




Join Date: Jan 2012
Location: Long Island, NY
Posts: 344
Problem with DA18-135 lens

I recently received advice in these Forums on huge underexposures I was experiencing on my K50/DA 18-135 combo. It turned out to be a common problem associated with an aperture block. I am now using the K50 with some old manual Tak lenses until I decide whether it's worth fixing the camera. In the meantime I was planning to use the 18-135 on a spare K100D body that I have. I was distressed to find that I couldn't get the lens to auto focus, except on the odd infrequent occasion. At one time, I couldn't get the camera to switch away from AWB (auto white balance). It seems to have fixed itself and now I can select from the different lighting options. When I select manual focussing, the camera works fine but I prefer to use auto focussing for convenience. I cleaned all the electrical contacts and installed fully charged batteries but it didn't help.

I was beginning to think about repairing either the K100D or the K50 but, on a whim, I slapped a couple of different lenses onto the K100D and found the auto focus worked perfectly. It showed the problem was with my 18-135 lens. I've had this lens for a couple of years and it has never let me down. What surprised me was that it was a lens failure rather than a camera failure. The fact that I couldn't switch away from AWB also seemed to indicate the camera was at fault rather than the lens. I thought that lenses almost never failed mechanically; it is always the camera. Is this true?

Now I need advice on whether the lens is worth fixing. It's not something I would dare to attempt myself. Can the fix be done cheaply? Any comments would be very welcome.

01-13-2017, 10:35 AM   #2
Pentaxian




Join Date: Apr 2016
Posts: 440
The lens is fine I think. The K100d hasn't got SDM contacts which are used by the lens so it is MF only.
01-13-2017, 10:44 AM   #3
Site Supporter
Site Supporter
luftfluss's Avatar

Join Date: Jun 2011
Location: NJ
Photos: Gallery | Albums
Posts: 5,719
As noted by HarisF1, you need an SDM-compatible body in order to AF with the 18-135. The oldest SDM camera is the K100D Super.

Last edited by luftfluss; 01-13-2017 at 10:57 AM.
01-13-2017, 11:27 AM   #4
amateur dirt farmer / mod
Loyal Site Supporter
pepperberry farm's Avatar

Join Date: Dec 2014
Location: probably out in a field somewhere...
Photos: Gallery | Albums
Posts: 15,653
no screw-drive on the DA18-135mm, so it won't work as an AF lens on that body - your K50, however, will need to be repaired or replaced....

or just used as a manual-lens-only body...

01-13-2017, 01:10 PM - 1 Like   #5
Site Supporter
Site Supporter




Join Date: Jan 2012
Location: Long Island, NY
Posts: 344
Original Poster
I thank you all for your rapid accurate responses. I'm very relieved to find my 18-135 is OK. What confused me, at first, was the observation that when the camera was set to "auto focus" it would once in a while give a beep as I panned around my den. The beep showed the lens was focused and it would give a sharp image. On all other occasions I could point the camera anywhere else and I would always get a "beepless" exposure, even when the lens was not in focus. The beep just signified that, that as I panned around the room, I had randomly pointed to an image that was in focus - hence the beep. When the camera didn't beep I made the incorrect assumption that the auto focus was broken when in fact the K100D didn't have this focussing feature. Thanks again for your help.

---------- Post added 01-13-17 at 03:25 PM ----------

Hi again Folks. I have another question. If the DA18-135 won't auto focus on the K100D because the latter doesn't have SDM contacts, why does it auto focus on a DA18-250 and a Sigma 24-70? I'm still confused.
01-13-2017, 01:32 PM   #6
Site Supporter
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Washington Cascades
Photos: Gallery | Albums
Posts: 11,846
QuoteOriginally posted by psoo Quote
Hi again Folks. I have another question. If the DA18-135 won't auto focus on the K100D because the latter doesn't have SDM contacts, why does it auto focus on a DA18-250 and a Sigma 24-70? I'm still confused.
Because those lenses have the older screwdrive functionality. Older lenses were all screwdrive, then some lenses had both, then newer lenses some only have the SDM system. The 18-135 has no screwdrive hardware so will only work with a camera body that supports SDM.
01-13-2017, 01:36 PM   #7
Site Supporter
Site Supporter




Join Date: Jan 2012
Location: Long Island, NY
Posts: 344
Original Poster
Thanks a lot Jatrax. I'm no longer confused
01-13-2017, 03:52 PM   #8
retired sw engineer
Loyal Site Supporter
reh321's Avatar

Join Date: Nov 2014
Location: South Bend, IN, USA
Photos: Gallery | Albums
Posts: 13,026
QuoteOriginally posted by psoo Quote
I thank you all for your rapid accurate responses. I'm very relieved to find my 18-135 is OK. What confused me, at first, was the observation that when the camera was set to "auto focus" it would once in a while give a beep as I panned around my den. The beep showed the lens was focused and it would give a sharp image. On all other occasions I could point the camera anywhere else and I would always get a "beepless" exposure, even when the lens was not in focus. The beep just signified that, that as I panned around the room, I had randomly pointed to an image that was in focus - hence the beep. When the camera didn't beep I made the incorrect assumption that the auto focus was broken when in fact the K100D didn't have this focussing feature. Thanks again for your help.
In order to be more stealthy, I have the sound turned off, so the "beep" confused me at first, but I believe you're simply seeing focus confirmation at work; i.e., at random times you'd be pointed at objects that just happened to be at the distance the lens was focused at.

01-13-2017, 04:26 PM   #9
Site Supporter
Site Supporter




Join Date: Jan 2012
Location: Long Island, NY
Posts: 344
Original Poster
QuoteOriginally posted by reh321 Quote
In order to be more stealthy, I have the sound turned off, so the "beep" confused me at first, but I believe you're simply seeing focus confirmation at work; i.e., at random times you'd be pointed at objects that just happened to be at the distance the lens was focused at.
Hi Reh, that's exactly what I thought. Thanks.
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!
auto, awb, beep, camera, couple, da18-135 lens problem, dslr, failure, focus, image, k100d, k50, lens, lenses, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hyperfocusing with DA lenses (eg. DA15, DA18-135, DA21)....how to? raider Pentax SLR Lens Discussion 50 03-08-2016 12:50 AM
Some questions in regard to Pentax DA18-135 superzoom lens Bandit2006 Pentax SLR Lens Discussion 10 01-01-2013 02:45 PM
Landscape Mountain Panorama with DA18-135 Mr_Canuck Post Your Photos! 8 05-09-2012 05:01 AM
Landscape Flowers with DA18-135 Mr_Canuck Post Your Photos! 3 05-20-2011 01:12 PM
DA18-135 or DA18-250? jatrax Pentax SLR Lens Discussion 17 04-25-2011 08:41 PM



All times are GMT -7. The time now is 08:12 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