On Wed, 10 Nov 2010 22:47:46 -0500 "P. J. Alling" <webstertwenty...@gmail.com> wrote:
> That combination works very well together. The largest problem is > achieving focus lock. Pentax doesn't recommend the AF 1.7x being > used with lenses having a slower maximum aperture than f2.8. This > results in a maximum aperture equivalent to f4.6. Using it with an > f4.0 lens gives a maximum aperture of ~f6.7 which is 2/3 of a stop > slower than the slowest maximum aperture, (f5.6), I've ever seen on > a Pentax auto focus lens. At those apertures the cameras really > struggle to focus in even moderately low light conditions. However > in bright light AF is no real problem and the images are quite sharp. that's reassuring to know. i guessed it could be because of the slower f/4, though the user manual does list a f3.5 zoom... thanks, subash -- 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.
