Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
04-05-2012, 02:58 PM   #1
Veteran Member

Join Date: Dec 2007
Location: traverse city MI
Posts: 342
using Sigma tele extenders with other brand lenses

I have 3 lenses two pentax and one tamron 17-50 2.8 and have found a nice deal on two sigma tele extenders one a 2x ex dg apo and the other a 1.4 ex dg apo
are the tele extenders compatable with any pentax mount or only with sigma lenses. any input would be appreciated.

04-05-2012, 03:10 PM   #2
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 43,668
They'll work I believe, but you won't get AF.

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:

04-05-2012, 04:13 PM   #3
Inactive Account

Join Date: Mar 2011
Posts: 121
The Sigma TCs protrude forward, so if the Pentax lens has depth between the mount and the rear lens element they will work, but otherwise they will not. You will have autofocus for screwdrive autofocus lenses but not for SDM drive. The Sigma TCs definitely work on the Pentax 300mm DA*. There isn't much reason to use a TC or shorter lenses. They are designed to extend the reach of long glass.
04-05-2012, 05:08 PM   #4
Bob from Aus's Avatar

Join Date: Jul 2011
Location: Australia
Photos: Gallery
Posts: 1,086
I understood that the current sigma TCs protruded into the space of the lens it was attached to. When the glass of some lenses zoom or focus they can crunch into the protruding TC. Sigma has a chart showing which of their lenses can be used with it, but not for other makes. Are we talking about the same TCs?

04-05-2012, 06:20 PM   #5
philbaum's Avatar

Join Date: Oct 2007
Location: Port Townsend, Washington State, USA
Posts: 3,659
I have the DA300 and tried my brother's 2x Sigma TC on it. It fits and has the 7 electrical contacts, but has no Pz contacts so cannot do SDM or Sigma's hsm. The electrical contacts allow one to change apertures on lenses like the modern 300 which have no aperture ring. But AF will not work on sdm lenses. AF might work on FA and F AF lenses (my guess-haven't tried it) and other 3rd party screw drive lenses like Tamron's 28-75 f2.8.

  • 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!
apo, dg, extenders, k-mount, lenses, pentax, pentax lens, sigma, slr lens, tele
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
Which tubes, extenders, teleconverter? t.stone Troubleshooting and Beginner Help 24 04-22-2011 11:33 AM
For Sale - Sold: Pentax 1.7x AF tele-converter, Brand New! seamanca Sold Items 32 01-24-2008 02:52 PM
For Sale - Sold: Pentax 1.7x auto focus tele converter - Brand New! seamanca Sold Items 14 12-29-2007 02:36 PM
For Sale - Sold: FS: Pentax 1.7x auto focus tele converter - Brand New! seamanca Sold Items 5 10-17-2007 10:02 PM
For Sale - Sold: FS: Pentax 1.7x auto focus tele converter - Brand New! seamanca Sold Items 6 09-29-2007 11:00 PM

All times are GMT -7. The time now is 11:15 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]