Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
08-19-2011, 05:13 PM   #1
New Member

Join Date: Aug 2011
Location: Idaho
Posts: 4
Pentax D-100 lens help

I just recently purchased this lens after much research. It's supposed to be compatible with my camera, however I'm having an issue. The lens fits perfectly, clicks in place, manual focus works beautifully, the autofocus does not work. This is actually the second lens I got from B & H because when I got the first one it did this too and I thought it was defective. Now I'm wondering if they are not compatible or if I'm doing something wrong. Please help!

Sigma 18-50mm f/2.8-4.5 DC OS HSM Zoom For Pentax 861109 B&H

08-19-2011, 05:21 PM   #2
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 43,128
The K100D doesn't support SDM (HSM on Sigma lenses) autofocus. You'll want to upgrade to a K100D super, or to a K-r (that would probably be easiest).

Adam Webmaster (Site Usage Guide | Site Help | My Photography)'s high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

08-19-2011, 06:35 PM   #3
New Member

Join Date: Aug 2011
Location: Idaho
Posts: 4
Original Poster
So is there nothing I can do to make this work? I was really looking forward to a lens with lower aperture.
08-19-2011, 06:47 PM   #4
Community Manager
Loyal Site Supporter
Ash's Avatar

Join Date: Mar 2007
Location: Toowoomba, Queensland
Photos: Gallery | Albums
Posts: 22,695
Unfortunately not. The screwdrive autofocus mechanism is not buit into the Sigma HSM lens, so it will not work on your current camera. Good reason to upgrade your camera to a K-x or K-r.

08-19-2011, 06:51 PM   #5
New Member

Join Date: Aug 2011
Location: Idaho
Posts: 4
Original Poster
Bummer! Can anyone recommend a lens that would be compatible with lower aperture, zoom, and autofocus?
08-19-2011, 07:29 PM   #6
Site Supporter
SpecialK's Avatar

Join Date: Dec 2006
Location: So California
Photos: Gallery
Posts: 14,901
Any of the DA type of Pentax lenses, and a lot of other brands make compatible lens - just avoid "SDM" and "HSM" and other lenses with reference to a silent focusing motor.

You can check out the Lens Database in the "Lenses" link at the top of this page.

You might find an older Sigma 17-70 or Sigma 18-50 in the Marketplace, or make a Wanted post.

Last edited by SpecialK; 08-19-2011 at 07:35 PM.
08-24-2011, 07:40 PM   #7

Join Date: Apr 2007
Location: Oklahoma USA
Posts: 1,502
I think the Tamron 17-50mm for Pentax has screw drive, but I'm not sure. Many people here own that lens and I'm sure they'll reply.

08-26-2011, 07:20 AM   #8
New Member

Join Date: Aug 2011
Location: Idaho
Posts: 4
Original Poster
Thanks! Is this the lens you were talking about? Does anyone know if it is compatible??? Oh and I'm not sure why I wrote D-100 when my camera is a k100.

Tamron 17-50mm f/2.8 XR Di-II LD Aspherical [IF] AF016P-700 B&H

08-26-2011, 08:18 PM   #9

Join Date: Apr 2007
Location: Oklahoma USA
Posts: 1,502
Sorry, I have a K100 but not that lens. If you can't find the info with a search, post a question in the lens forum and someone can confirm/deny if it has screw drive. That is the lens I was thinking of.


  • 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!
lens, pentax, pentax help
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
HELP - Pentax FA 100-300 f4.7 Lens not working in Av mode gut1kor Pentax SLR Lens Discussion 11 05-25-2011 07:02 PM
Broken Pentax FA 100-300mm lens? savcom Pentax SLR Lens Discussion 2 07-12-2010 03:21 PM
Pentax Auto 100 lens McG Pentax SLR Lens Discussion 2 06-19-2010 05:50 PM
For Sale - Sold: 100-300mm lens for Pentax AF Quantaray jgmankos Sold Items 6 11-27-2009 06:11 AM
Pentax DA 100/2.8 macro lens problem switch Pentax SLR Lens Discussion 7 08-31-2009 06:29 PM

All times are GMT -7. The time now is 06:13 AM. | See also:, 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?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]