Michael, I don't know that any of them really stand out. They are all designed about the same and cost about the same. I seem to recall that both Tamron and Tokina made some more recent Pro grade converters but didn't make them in Pentax mount.
Basically, your quality will go down as the power goes up. The 1.4/5 converters will suffer less optical quality drop than the 2X's. I personally have a Tamron 2X AF converter and it does in a pinch. Bruce Friday, December 6, 2002, 4:53:02 PM, you wrote: MC> Thanks Bruce, MC> Is there one of the Tamron/Tokina/Sigma (and I think Kenko makes one MC> too) that stands out? MC> Michael MC> Bruce Dayton wrote: >>Michael, >> >>I believe you can. However, the AF teleconverter is not a perfect >>solution. You have to help it to focus (get in the general area >>manually and let it finish the job). Putting an FA lens on is just >>the same as putting an A lens on. There is no use of the lens's >>capability to focus, just the converter. Tamron, Tokina and Sigma all >>make 1.4/5 teleconverters that pass the focus shaft on through >>allowing your FA lens to focus it's full range. >> >>The Pentax one is really designed for lenses that are not AF already. >> >> >>Bruce >> >> >> >>Friday, December 6, 2002, 4:09:16 PM, you wrote: >> >>MC> Does anyone know if you can use an FA lens with the 1.7AF TC? >> >>MC> Michael Cross >> >>MC> Doug Franklin wrote: >> >> >> >>>>Hi John, >>>> >>>>On Fri, 06 Dec 2002 13:02:50 -0500, John Daniele wrote: >>>> >>>> >>>> >>>> >>>> >>>>>Anyone ever try the pentax 1.7x converter that changes manual >>>>>focus to af >>>>> >>>>> >>>>> >>>>> >>>>I've used the 1.7X AF TC on both a ZX-5 and an MZ-S, with Tamron >>>>90/2.5, Pentax SMC-A 200/4, and Pentax SMC-A 50/1.4. I've been very >>>>pleased with the results. The T/C works extremely well with the 50/1.4 >>>>and 90/2.5. It hunts a bit with the 200/4, probably due to the drop in >>>>light transmission. >>>> >>>>TTYL, DougF KG4LMZ >>>> >>>> >>>> >>>> >>>> >>>> >>>> >> >> >> >>
