Bob sorry wrote that in a hurry. The beauty of the F1.7x AF teleconverter is that it can autofocus manual focus lenses (or AF lenses set to MF as in my case with the Sigma 300). You manually set the approximate focal length on the lens and put the camera on AF and when you fire the shutter the AF mechanism drives internal elements within the t/c to autofocus the image within the tolerance limits of the t/c (it can't focus when the lens is set to a focal length that is a long way from the correct setting for the subject in view). The result is a very fast autofocus and no hunting up and down the focal length of the lens, which is what tends to happen in low light levels when you have a AF lens mounted directly. Some AF lenses have focal limits which acheives the same sort of effect but is less flexible and slower than the result using the t/c. Hope that makes more sense!
see Boz's page if your not familiar with this beast http://www.bdimitrov.de/kmp/teleconverters/F1.7X.html These things are like hen's teeth and fetch ridiculous prices on ebay of more than $600! I am still kicking myself when I was too slow to pick another one up from a NZ shop that had it at NZ$95 recently (about US$60). Alastair On Dec 8, 2007 6:16 PM, Bob Sullivan <[EMAIL PROTECTED]> wrote: > Technically you just lost me... Regards, Bob S. > > > On Dec 7, 2007 9:24 PM, Alastair Robertson <[EMAIL PROTECTED]> wrote: > > http://www.pbase.com/image/90022721 > > > > Taken at home - trying to get bird pictures again, but captured the > > white blooms of the rose "iceberg" up against the dark hedge. > > > > Specs: K10D AF1.7x Sigma 300/4 APO monopod > > 1/2000 F4.0 ISO200 > > > > Not the sharpest combination at this aperture but quick AF response > > since you set the approx focal length on the lens and put it on MF and > > the camera on AF and even at low light levels the AF doesn't hunt > > since you have effectively limited the focal length the AF of the > > camera can explore. > > > > Alastair > > > > -- > > 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. > -- 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.
