Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
04-20-2009, 09:20 PM   #1
Veteran Member
res3567's Avatar

Join Date: Sep 2008
Location: Houston Tx.
Photos: Gallery
Posts: 1,876
Pentax TC

I read somewere online that Pentax made or is going to make a TC that will convert manual focus lenses to autofocus. Is this true and how? I asume you would set the MF lens to infinity and the TC rotates to focus? Anyone ever heard of this?

04-20-2009, 09:24 PM   #2
Veteran Member
Andi Lo's Avatar

Join Date: Jul 2008
Location: Halifax, Nova Scotia
Posts: 2,925
Pentax F 1.7x AF TC from the F generation turns MF lens into AF. You set the lens to close enough to focused and trigger AF, then the TC elements will move and lock on the focus. Prices for one of these guys range from 300 to 400$

I think it's safe to assume that had the DA generation 1.7x TC is still in the roadmap and is released, it will have this capability as well.
04-20-2009, 10:51 PM   #3
Veteran Member
res3567's Avatar

Join Date: Sep 2008
Location: Houston Tx.
Photos: Gallery
Posts: 1,876
Original Poster
QuoteOriginally posted by Andi Lo Quote
Pentax F 1.7x AF TC from the F generation turns MF lens into AF. You set the lens to close enough to focused and trigger AF, then the TC elements will move and lock on the focus. Prices for one of these guys range from 300 to 400$

I think it's safe to assume that had the DA generation 1.7x TC is still in the roadmap and is released, it will have this capability as well.
Is it a quality item? Don't see a whole lot on it yet......
04-20-2009, 10:58 PM   #4
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
It's considered very good, and fetches a pretty high price for a TC on Ebay. It gets mentioned quite a bit here.

04-20-2009, 11:07 PM   #5
Veteran Member
res3567's Avatar

Join Date: Sep 2008
Location: Houston Tx.
Photos: Gallery
Posts: 1,876
Original Poster
QuoteOriginally posted by Marc Sabatella Quote
It's considered very good, and fetches a pretty high price for a TC on Ebay. It gets mentioned quite a bit here.

Ok Marc. Thank You!

Do you have it? If not would you consider buying it?

I like shooting sports and I have some MF teles that may benifit from this TC.
04-20-2009, 11:32 PM   #6
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
I don't have one. I have only the Kenko 1.5 TC. Doubtless not as good, but I'm not interested in spending hundreds more on another TC.
04-21-2009, 09:54 AM   #7
Pentaxian
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,427
QuoteOriginally posted by res3567 Quote
I read somewere online that Pentax made or is going to make a TC that will convert manual focus lenses to autofocus. Is this true and how? I asume you would set the MF lens to infinity and the TC rotates to focus? Anyone ever heard of this?
I have used this Pentax-F 1.7x AF TC on various lens. And yes, it can work with manual focus lenses and turn it into AF when you first manual focus close to target. Please note that it is not completely AF as you first have to manual focus your lens close to target and the half press for AF will let the AF mechanics in TC to work. If you focus at infinity and intend to focus at close distance, the AF in the TC will fail and you will get blinking in failing to obtain focus confirmation. The caveat lies in manual focus first to get to a close target point and let the TC magical AF to work. In short, it works quite reliably after some use and adaptation on how the TC works.

It works best on manual focus lenses with 'A' setting but I also use it to various degree of success with inexpensive AF zoom, K lens without 'A' and M42 lens. You lose 1.5 stop of light.

Here is a picture of mounting the Pentax-F 1.7x AF TC with foil on my Photosniper Tair-3 PhS 300mm f/4.5 in m42 mount to cover the electrical contacts. Without foil, I can't get the AF to work on the TC with m42 lens.






510mm with AF from the TC

04-21-2009, 10:17 AM   #8
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,400
just to give an idea of the quality, this is from my *istD with the 300mm F4 and AF500FTZ flash

I find the quality is very good



04-21-2009, 10:38 AM   #9
Pentaxian
hinman's Avatar

Join Date: Oct 2006
Location: Fremont, CA
Photos: Albums
Posts: 3,427
I have used this TC to work with various other tele prime and inexpensive zoom lens


In my opinion, all caveats need to be considered in use of TC but I give this TC the edge over the other AF TC on two areas
  • It can turn manual focus lenses into AF
  • It can allow input for SR focal length for AF lens, you can't do that with Tamron 1.4x or other AF TC

Last edited by hinman; 04-21-2009 at 11:11 AM.
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!
focus, k-mount, pentax, pentax lens, slr lens, tc
Thread Tools Search this Thread
Search this Thread:

Advanced Search



All times are GMT -7. The time now is 05:27 AM. | 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