John, I think what you experience may be a natural result of the AF sensitivity, requiring lenses with max apertures of f/5.6 or brighter. If you start out with an f/4 lens, an 1.4x converter is about as much as you can hope to get away with. The 1.5x steals just that little extra light to screw up the AF.
Jostein 2009/5/11 John Whittingham <[email protected]>: > Hi Tim > > I'm having troubles with the DA*300/4, whenerver I fit a Kenko 1.5x SHQ > converter to the rear it hunts just either side of the subject constantly but > never locks focus. When used on a tripod some time ago it worked just fine, > the Teleplus i.7x converter displays the same behaviour when hand held but > more so. On my last visit to Mere Sands Wood I ended up going back to my > Sigma 300/4 APO and 1.4x EX converter and they worked fine. I'm wondering if > investing in a Tamron 1.4x converter may be the way to go, if I can find one. > Pentax seem to have dropped the SDM converter from the roadmap, I woder if > they may have discovered the same problem. BTW the Kenko and Teleplus support > SDM, the Sigma does not. > > Best regards, > > John > ________________________________________ > From: [email protected] [[email protected]] On Behalf Of Tim Øsleby > [[email protected]] > Sent: 11 May 2009 14:21 > To: Pentax-Discuss Mail List > Subject: Re: PESO - Wagtail > > The Pentax F 1,7X AF. The one that provides semi-AF on MF lenses. > > A handy thing, but it dos'nt seem to like my other lenses. > > -- > MaritimTim > > 2009/5/11 John Whittingham <[email protected]>: >> Nice capture, we have a breeding pair here where I work, see them on a >> regular basis but have never photographed them. What 1.7x TC were you using? >> >> Regards, >> >> John >> ________________________________________ >> From: [email protected] [[email protected]] On Behalf Of Tim Øsleby >> [[email protected]] >> Sent: 11 May 2009 00:32 >> To: Pentax-Discuss Mail List >> Subject: PESO - Wagtail >> >> This little fella came passing by today. >> http://www.diskusjon.no/index.php?act=attach&type=post&id=300079 >> >> Handheld 300/2,8 + 1,7x >> >> -- >> MaritimTim >> > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > -- http://www.alunfoto.no/galleri/ http://alunfoto.blogspot.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
