Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
03-08-2010, 03:00 PM   #1
Veteran Member




Join Date: Feb 2009
Location: Portland, OR
Photos: Albums
Posts: 325
teleconverter for FA 100-300 f/4.7-5.6

Hey all, are there any teleconverters that would maintain AF and AE @ 300mm on this lens?

Thanks in advance! Its looking like the answer will be no

03-08-2010, 03:06 PM   #2
Veteran Member
Shashinki's Avatar

Join Date: Jan 2008
Location: Norway
Posts: 357
AF on f/5.6 with a TC is pretty doubtful. With a 1.4X it would be f/8 and manual focus seems to be the only option as far as I know.
(edit: If you had a Canon 1D series camera or a camera with a very sensitive AF-sensor, autofocus at f/8 might be possible, but FA lenses do not work well on Canon 1D bodies anyways... )

Last edited by Shashinki; 03-08-2010 at 03:12 PM.
03-08-2010, 03:11 PM   #3
Veteran Member
clawhammer's Avatar

Join Date: Sep 2007
Location: Logan, Utah
Photos: Gallery
Posts: 975
I've thrown a cheap 2.0x on my 100-300 4.5-6.3 (so half a stop slower than your 5.6), and AF was iffy. If the subject contrast was good it found focus, but most of the time it just hunted really, really slow. I wouldn't recommend it, and the quality hit on a consumer-level lens probably wouldn't be worth it.
03-08-2010, 03:19 PM   #4
Veteran Member




Join Date: Feb 2009
Location: Portland, OR
Photos: Albums
Posts: 325
Original Poster
yeah you guys are hitting on what I was thinking...dang, looks like i've got to improve my tactics instead of just getting more length!

03-08-2010, 03:23 PM   #5
Veteran Member
Shashinki's Avatar

Join Date: Jan 2008
Location: Norway
Posts: 357
http://hairyfarmerfamily.files.wordpress.com/2009/12/camouflage.jpg
03-08-2010, 03:37 PM   #6
Veteran Member




Join Date: Feb 2009
Location: Portland, OR
Photos: Albums
Posts: 325
Original Poster
lol!

I'm going to get myself a blind...I'm too fidgety to just sit out in the open. Either a chair blind I can barricade myself in or one that'll hold a friend and I.

thinking about it, when I rented the bigma, the difference between 300 and 500 wasn't all that much, considering the costs of getting to 500.
03-08-2010, 04:37 PM   #7
Pentaxian




Join Date: Feb 2009
Location: Alameda, CA
Posts: 3,194
QuoteOriginally posted by jmbradd Quote
Hey all, are there any teleconverters that would maintain AF and AE @ 300mm on this lens?

Thanks in advance! Its looking like the answer will be no
I bet you a good 1.4X TC (e.g. Tamron) will work. At the long end, you may need to find something contrasty for the focusing sensors to lock on, but it will work.

I tried my Tamron 1.4X TC with the Tamron 18-250 F/3.5-6.3. At 250mm, auto focus indoor is slow and hunting quite a bit. But with sufficient light outdoor, auto focus at 250mm is slow, but bearable.

F/5.6 is almost half a stop faster than F/6.3. So I think auto focus is OK.
03-08-2010, 04:46 PM   #8
Veteran Member
dgaies's Avatar

Join Date: Oct 2009
Location: Maryland / Washington DC
Posts: 3,917
QuoteOriginally posted by SOldBear Quote
I bet you a good 1.4X TC (e.g. Tamron) will work. At the long end, you may need to find something contrasty for the focusing sensors to lock on, but it will work.

I tried my Tamron 1.4X TC with the Tamron 18-250 F/3.5-6.3. At 250mm, auto focus indoor is slow and hunting quite a bit. But with sufficient light outdoor, auto focus at 250mm is slow, but bearable.

F/5.6 is almost half a stop faster than F/6.3. So I think auto focus is OK.
I can confirm that the Tamron 1.4x with the DA55-300/4.0-5.8 (on a Kx body) works fairly well. Again, indoors at 300mm the AF is a little slow and you need a target with some decent contrast. It's also nice to have the quick-shift of the DA55-300 to get the focus close before using the AF. Outdoors, the AF with the 1.4x is typically much better.

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
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Tamron adaptall 300/2.8 or Sigma 100-300/4 pinholecam Pentax SLR Lens Discussion 10 11-07-2009 05:52 AM
Tamron 300/2.8, Sigma 100-300 F4, 1.7 AF TC images: A link to the DPR froum. pcarfan Pentax SLR Lens Discussion 0 02-07-2009 08:48 PM
Wildlife & sports tele: DA*300 vs Sigma 100-300 f4 dspdx Pentax SLR Lens Discussion 4 08-28-2008 09:27 PM
Sigma 100-300 APO vs New Pentax 300 dylansalt Pentax SLR Lens Discussion 10 07-24-2008 05:44 AM
70-300 and a 2x teleconverter metalfab Pentax SLR Lens Discussion 9 04-21-2008 07:51 AM



All times are GMT -7. The time now is 01:58 AM. | See also: NikonForums.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