On Aug 31, 2011, at 11:03 PM, Stan Halpin wrote: > Wishful thinking alert: Pentax needs a system that will allow their DA*400 or > 500mm lens to AF with a 2x extender. So, either reasonably fast glass or a > much improved AF system that works well @f8-11 in low contrast dim light. >
I think we're halfway there, given the performance of the K5 with SDM lenses. If they continue to make progress at the same rate, that kind of performance will happen soon. Remember too, that focusing a long lens is a bit easier than focusing a wide lens. Paul > stan > > Sent from my iPhone > > On Aug 31, 2011, at 5:24 PM, Larry Colen <l...@red4est.com> wrote: > >> I think that part of the reason that the adaptall mount went out of favor is >> the difficulty and complexity of doing a screw-drive autofocus version. >> It's one thing to make a linkage that'll handle f-stops, but the tolerance >> you need for screwdrive would be really tough to pass through an adaptall >> style mount. However, SDM is an electronic connection, not a mechanical >> one. For that matter, you wouldn't even need a mechanical linkage for >> aperture, just the stop-down actuator. >> >> I was contemplating that with sensors improving so quickly, that it's barely >> cost effective to spend the money making fast glass, to get a stop or two, >> when sensors will give that same speed in a couple years time anyways, for a >> lot cheaper. Therefore, fast primes are going to quickly become a niche >> market, especially in DSLR mounts, and that there probably aren't enough >> Pentax mount DSLRs out there to justify the development costs of new fast >> prime optics. However, it might be economically feasible for a boutique >> optics company to make fast primes using something akin to an adaptall >> system. >> >> -- >> Larry Colen l...@red4est.com sent from i4est >> >> >> >> >> >> -- >> PDML Pentax-Discuss Mail List >> PDML@pdml.net >> 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 > PDML@pdml.net > 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 PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
