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 [email protected] sent from i4est -- 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.
